Danfoss FC 100 Series Soft Start Controller Installation Guide
- June 1, 2024
- Danfoss
Table of Contents
Danfoss FC 100 Series Soft Start Controller
Specifications
- Software Version: 2.5x
- Compatibility: All VLT HVAC adjustable frequency drives with software version 2.5x
Product Information
The VLT HVAC Drive FC 100 Series is designed for use with HVAC systems and offers advanced control features for efficient operation.
Safety Features
- CE labeling for compliance with safety standards
- Designed to operate in various air humidity conditions
- Resistant to aggressive environments
- Shock and vibration resistant
Control and Operation
- PID control for precise operation
- EMC compliant for electromagnetic compatibility
- Galvanic isolation (PELV) for enhanced safety
- Control with brake function for specific applications
VLT HVAC Selection
- Efficiency optimization for energy savings
- Low acoustic noise for quiet operation
- Peak voltage on motor regulation
- Special conditions support
- Options and accessories availability for customization
Product Usage Instructions
Installation
- Mechanical Installation: Follow the guidelines provided in the manual to securely mount the VLT HVAC Drive.
- Electrical Installation: Connect the drive to the power supply following the specified wiring diagram.
Application Examples
Utilize different control modes such as Start/Stop, Potentiometer Reference, Automatic Motor Adaptation (AMA), and more based on your HVAC system requirements.
RS-485 Installation and Set-up
Set up the RS-485 communication protocol using the provided guidelines for network configuration and message framing.
Troubleshooting
Refer to the manual for a list of alarms, warnings, and fault messages to troubleshoot any issues that may arise during operation.
FAQs
- Q: How can I determine the software version of my VLT HVAC Drive?
- A: You can find the software version number in parameter 15-43 of the drive.
- Q: What safety features does the VLT HVAC Drive offer?
- A: The drive includes CE labeling, resistance to air humidity, shock, vibration, and control with brake function for enhanced safety.
- Q: How do I optimize energy efficiency with the VLT HVAC Drive?
- A: You can optimize energy efficiency by utilizing the efficiency settings and options available in the drive. Refer to the manual for detailed instructions.
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VLT® HVAC Drive Design Guide
Contents
1 How to Read this Design Guide
Copyright, Limitation of Liability and Revision Rights Approvals Symbols
Abbreviations Definitions
2 Introduction to the VLT HVAC Drive
Safety CE labeling Air humidity Aggressive Environments Vibration and shock
VLT HVAC Controls PID General aspects of EMC Galvanic isolation (PELV) Ground
leakage current Control with brake function Mechanical brake control Extreme
running conditions Safe Stop
3 VLT HVAC Selection
Specifications Efficiency Acoustic noise Peak voltage on motor Special
Conditions Options and Accessories
4 How to Order
Ordering form Ordering Numbers
5 How to Install
Mechanical Installation Electrical Installation
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
Contents
1-1 1-2 1-3 1-3 1-4 1-4
2-1 2-1 2-2 2-4 2-4 2-5 2-18 2-20 2-31 2-33 2-34 2-35 2-37 2-38 2-39
3-1 3-1 3-12 3-13 3-14 3-14 3-19
4-1 4-1 4-3
5-1 5-1 5-6
Contents
Final Set-Up and Test Additional Connections Installation of misc. connections
Safety EMC-correct Installation AC Line Supply Interference/Harmonics Residual
Current Device
6 Application Examples
Start/Stop Pulse Start/Stop Potentiometer Reference Automatic Motor Adaptation
(AMA) Smart Logic Control Smart Logic Control Programming SLC Application
Example BASIC Cascade Controller Pump Staging with Lead Pump Alternation
System Status and Operation Fixed Variable Speed Pump Wiring Diagram Lead Pump
Alternation Wiring Diagram Cascade Controller Wiring Diagram Start/Stop
conditions Compressor Cascade Control
7 RS-485 Installation and Set-up
RS-485 Installation and Set-up FC Protocol Overview Network Configuration FC
Protocol Message Framing Structure Examples Modbus RTU Overview Modbus RTU
Message Framing Structure How to Access Parameters Examples Danfoss FC Control
Profile
8 Troubleshooting
Alarms and warnings
VLT® HVAC Drive Design Guide
5-19 5-22 5-26 5-29 5-29 5-33 5-34
6-1 6-1 6-1 6-2 6-2 6-2 6-3 6-3 6-5 6-6 6-6 6-7 6-8 6-8 6-9 6-10
7-1 7-1 7-3 7-4 7-5 7-11 7-12 7-13 7-17 7-19 7-25
8-1 8-1
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VLT® HVAC Drive Design Guide
Alarm words Warning words Extended status words Fault messages
9 Index
Contents
8-4 8-5 8-6 8-7
9-1
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Contents
VLT® HVAC Drive Design Guide
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
VLT® HVAC Drive Design Guide
How to Read this Design Guide
1 How to Read this Design Guide
1
VLT HVAC Drive FC 100 Series Design Guide
Software version: 2.5x
This design guide can be used for all VLT HVAC adjustable frequency drives
with software version 2.5x.
The software version number can be seen from parameter 15-43.
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
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How to Read this Design Guide
VLT® HVAC Drive Design Guide
1.1.1 Copyright, Limitation of Liability and Revision Rights
1
This publication contains information proprietary to Danfoss A/S. By accepting and using this manual, the user agrees that the information contained
herein will be used solely for operating equipment from Danfoss A/S or equipment from other vendors, provided that such equipment is intended for
communication with Danfoss equipment over a serial communication link. This publication is protected under the copyright laws of Denmark and most
other countries.
Danfoss A/S does not guarantee that a software program produced according to the guidelines provided in this manual will function properly in every physical, hardware or software environment.
Although Danfoss A/S has tested and reviewed the documentation within this manual, Danfoss A/S makes no warranty or representation, neither expressed nor implied, with respect to this documentation, including its quality, performance, or fitness for a particular purpose.
In no event shall Danfoss A/S be liable for direct, indirect, special, incidental or consequential damages arising from the use or the inability to use information contained in this manual, even if advised of the possibility of such damages. In particular, Danfoss A/S is not responsible for any costs, including, but not limited to, those incurred as a result of lost profits or revenue, loss of or damages to equipment, loss of computer programs, loss of data, the costs to substitute these, or any claims by third parties.
Danfoss A/S reserves the right to revise this publication at any time and to make changes to its contents without prior notice or any obligation to notify former or present users of such revisions or changes.
1.1.2 Available Literature
– Instruction Manual MG.11.Ax.yy provides the neccessary information for
getting the drive up and running. – Design Guide MG.11.Bx.yy provides all the
technical information about the drive and customer design and applications. –
Programming Guide MG.11.Cx.yy provides information on how to program and
includes complete parameter descriptions. – Mounting Instruction, Analog I/O
Option MCB109, MI.38.Bx.yy – VLT® 6000 HVAC Application Booklet, MN.60.Ix.yy –
Instruction Manual VLT®HVAC Drive BACnet, MG.11.Dx.yy – Instruction Manual
VLT®HVAC Drive Profibus, MG.33.Cx.yy. – Instruction Manual VLT®HVAC Drive
Device Net, MG.33.Dx.yy – Instruction Manual VLT® HVAC Drive LonWorks,
MG.11.Ex.yy – Instruction Manual VLT® HVAC Drive High Power, MG.11.Fx.yy –
Instruction Manual VLT® HVAC Drive Metasys, MG.11.Gx.yy x = Revision number yy
= Language code Danfoss Drives technical literature is also available online
at
www.danfoss.com/BusinessAreas/DrivesSolutions/Documentations/Technical+Documentation.htm
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VLT® HVAC Drive Design Guide 1.1.3 Approvals
1.1.4 Symbols
Symbols used in this guide. NOTE! Indicates something to be noted by the
reader. Indicates a general warning.
Indicates a high-voltage warning.
- Indicates default setting
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1.1.5 Abbreviations
1
Alternating current
American wire gauge
Ampere/AMP
Automatic Motor Adaptation
Current limit
Degrees Celsius
Direct current
Drive Dependent
Electro Magnetic Compatibility
Electronic Thermal Relay
drive
Gram
Hertz
Kilohertz
Local Control Panel
Meter
Millihenry Inductance
Milliampere
Millisecond
Minute
Motion Control Tool
Nanofarad
Newton Meters
Nominal motor current
Nominal motor frequency
Nominal motor power
Nominal motor voltage
Parameter
Protective Extra Low Voltage
Printed Circuit Board
Rated Inverter Output Current
Revolutions Per Minute
Second
Torque limit
Volt
VLT® HVAC Drive Design Guide
AC AWG A AMA ILIM °C DC D-TYPE EMC ETR FC g Hz kHz LCP m mH mA ms min MCT nF
Nm IM,N fM,N PM,N UM,N par. PELV PCB IINV RPM s TLIM V
1.1.6 Definitions
Drive:
IVLT,MAX The maximum output current.
IVLT,N The rated output current supplied by the adjustable frequency drive.
UVLT, MAX The maximum output voltage.
Input:
Control command You can start and stop the connected motor using the LCP and the digital inputs. Functions are divided into two groups. Functions in group 1 have higher priority than functions in group 2.
Group 1 Group 2
Reset, Coasting stop, Reset and Coasting stop, Quick stop, DC braking, Stop and the “Off” key. Start, Pulse start, Reversing, Start reversing, Jog and Freeze output
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VLT® HVAC Drive Design Guide
Motor:
fJOG The motor frequency when the jog function is activated (via digital
terminals).
fM The motor frequency.
fMAX The maximum motor frequency.
fMIN The minimum motor frequency.
fM,N The rated motor frequency (nameplate data).
IM The motor current.
IM,N The rated motor current (nameplate data).
nM,N The rated motor speed (nameplate data).
PM,N The rated motor power (nameplate data).
TM,N The rated torque (motor).
UM The instantaneous motor voltage.
UM,N The rated motor voltage (nameplate data).
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Break-away torque
1
VLT® HVAC Drive Design Guide
VLT The efficiency of the adjustable frequency drive is defined as the ratio
between the power output and the power input.
Start-disable command A stop command belonging to the group 1 control commands
– see this group.
Stop command See Control commands.
References:
Analog Reference A signal transmitted to the analog inputs 53 or 54 can be
voltage or current.
Bus Reference A signal transmitted to the serial communication port (FC port).
Preset Reference A defined preset reference to be set from -100% to +100% of
the reference range. Selection of eight preset references via the digital
terminals.
Pulse Reference A pulse frequency signal transmitted to the digital inputs
(terminal 29 or 33).
RefMAX Determines the relationship between the reference input at 100% full
scale value (typically 10 V, 20 mA) and the resulting reference. The maximum
reference value set in par. 3-03.
RefMIN Determines the relationship between the reference input at 0% value
(typically 0 V, 0 mA, 4 mA) and the resulting reference. The minimum reference
value set in par. 3-02.
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1 How to Read this Design Guide
Miscellaneous:
Analog Inputs
1
The analog inputs are used for controlling various functions of the adjustable frequency drive.
There are two types of analog inputs:
Current input, 0-20 mA and 4-20 mA
Voltage input, 0-10 V DC.
Analog Outputs The analog outputs can supply a signal of 0-20 mA, 4-20 mA, or a digital signal.
Automatic Motor Adaptation, AMA AMA algorithm determines the electrical parameters for the connected motor at standstill.
Brake Resistor The brake resistor is a module capable of absorbing the braking energy generated in regenerative braking. This regenerative braking energy increases the intermediate circuit voltage, while a brake chopper ensures that the energy is transmitted to the brake resistor.
CT Characteristics Constant torque characteristics used for screw and scroll refrigeration compressors.
Digital Inputs The digital inputs can be used for controlling various functions of the adjustable frequency drive.
Digital Outputs The drive features two solid state outputs that can supply a 24 V DC (max. 40 mA) signal.
DSP Digital Signal Processor.
Relay Outputs: The adjustable frequency drive features two programmable relay outputs.
ETR Electronic Thermal Relay is a thermal load calculation based on present load and time. Its purpose is to estimate the motor temperature.
GLCP: Graphical Local Control Panel (LCP102)
Initializing If initializing is carried out (par. 14-22), the programmable parameters of the adjustable frequency drive return to their default settings.
Intermittent Duty Cycle An intermittent duty rating refers to a sequence of duty cycles. Each cycle consists of an on-load and an off-load period. The operation can be either a periodic or non-periodic duty.
LCP The Local Control Panel (LCP) makes up a complete interface for control and programming of the adjustable frequency drive. The control panel is detachable and can be installed up to 9.8 ft (3 meters) from the adjustable frequency drive, i.e. in a front panel by means of the installation kit option. The local control panel is available in two versions:
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VLT® HVAC Drive Design Guide
– Numerical LCP101 (NLCP) – Graphical LCP102 (GLCP)
1
lsb Least significant bit.
MCM Short for Mille Circular Mil, an American measuring unit for cable cross-
section. 1 MCM 0.00079 in.2 (0.5067 mm2).
msb Most significant bit.
NLCP Numerical Local Control Panel LCP101
Online/Offline Parameters Changes to online parameters are activated
immediately after the data value is changed. Changes to offline parameters are
not activated until you enter [OK] on the LCP.
PID Controller The PID controller maintains the desired speed, pressure,
temperature, etc. by adjusting the output frequency to match the varying load.
RCD Residual Current Device.
Set-up You can save parameter settings in four set-ups. Change between the
four parameter set-ups and edit one while another set-up is active.
SFAVM Switching pattern called Stator Flux oriented Asynchronous V ector M
odulation (par. 14-00).
Slip Compensation The adjustable frequency drive compensates for the motor
slip by giving the frequency a supplement that follows the measured motor
load, thus keeping the motor speed almost constant.
Smart Logic Control (SLC) The SLC is a sequence of user-defined actions
executed when the associated user-defined events are evaluated as true by the
SLC.
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Thermistor: A temperature-dependent resistor placed where the temperature is
to be monitored (adjustable frequency drive or motor).
1
Trip A state entered in fault situations, such as when the adjustable
frequency drive is subject to an overtemperature, or when the adjustable
frequency drive is protecting the motor, process or mechanism. Restart is
prevented until the cause of the fault has rectified and the trip state is
cancelled by activating reset, or, in some cases, by programming an automatic
reset. Trip may not be used as a personal safety measure.
Trip-Locked A state entered in fault situations when the adjustable frequency
drive is protecting itself and requiring physical intervention, such as when
the adjustable frequency drive is subject to a short circuit on the output. A
locked trip can only be cancelled by cutting off line power, removing the
cause of the fault and reconnecting the adjustable frequency drive. Restart is
prevented until the trip state is cancelled by activating reset or, in some
cases, by being programmed to reset automatically. The trip-lock function may
not be used as a personal safety measure.
VT Characteristics Variable torque characteristics used for pumps and fans.
VVCplus Compared with standard voltage/frequency ratio control, voltage vector
control (VVCplus) improves the dynamics and the stability, both when the speed
reference is changed and in relation to the load torque.
60° AVM Switching pattern called 60°Asynchronous Vector Modulation (See par.
14-00).
1.1.7 Power Factor
The power factor is the relation between I1 and IRMS. The power factor for
3-phase control:
Power factor =
3 × U × I1 × COS 3 × U × IRMS
=
I1
× cos1 IRMS
=
I1 IRMS
since
cos1 = 1
The power factor indicates to which extent the adjustable frequency drive imposes a load on the line supply. The lower the power factor, the higher the IRMS for the same kW performance.
IRMS =
I
2 1
I
2 5
I
2 7
. .
I
2 n
In addition, a high power factor indicates that the different harmonic currents are low. The adjustable frequency drive’s built-in DC coils produce a high power factor, which minimizes the imposed load on the line power supply.
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VLT® HVAC Drive Design Guide
1-10
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VLT® HVAC Drive Design Guide
Introduction to the VLT HVAC Drive
2 Introduction to the VLT HVAC Drive
2.1 Safety
2.1.1 Safety note
2
The voltage of the adjustable frequency drive is dangerous whenever connected to line power. Incorrect installation of the motor, adjustable frequency drive or serial communication bus may cause damage to the equipment, serious personal injury or death. Consequently, the instructions in this manual, as well as national and local rules and safety regulations, must be followed.
Safety Regulations 1. The adjustable frequency drive must be disconnected from
line power if repair work is to be carried out. Make sure that the line supply
has been disconnected and that the necessary time has passed before removing
motor and line plugs. 2. The [STOP/RESET] key on the control panel of the
adjustable frequency drive does not disconnect the equipment from line power
and is thus not to be used as a safety switch. 3. Correct protective grounding
of the equipment must be established, the user must be protected against
supply voltage, and the motor must be protected against overload in accordance
with applicable national and local regulations. 4. The ground leakage currents
are higher than 3.5 mA. 5. Protection against motor overload is set by par.
1-90 Motor Thermal Protection. If this function is desired, set par. 1-90 to
data value [ETR trip] (default value) or data value [ETR warning]. Note: The
function is initialized at 1.16 x rated motor current and rated motor
frequency. For the North American market: The ETR functions provide class 20
motor overload protection in accordance with NEC. 6. Do not remove the plugs
for the motor and line supply while the adjustable frequency drive is
connected to line power. Make sure that the line supply has been disconnected
and that the necessary time has passed before removing motor and line plugs.
7. Please note that the adjustable frequency drive has more voltage inputs
than L1, L2 and L3 when load sharing (linking of DC intermediate circuit) and
external 24 V DC have been installed. Make sure that all voltage inputs have
been disconnected and that the necessary time has passed before commencing
repair work.
Installation at High Altitudes
At altitudes higher than 6,600 feet [2 km], please contact Danfoss Drives
regarding PELV.
Warning against Unintended Start 1. The motor can be brought to a stop by
means of digital commands, bus commands, references or a local stop while the
adjustable frequency drive is connected to line power. If personal safety
considerations make it necessary to ensure that no unintended start occurs,
these stop functions are not sufficient. 2. While parameters are being
changed, the motor may start. Consequently, the stop key [STOP/RESET] must
always be activated, after which data can be modified. 3. A motor that has
been stopped may start if faults occur in the electronics of the adjustable
frequency drive, or if a temporary overload or a fault in the supply line or
the motor connection ceases.
Warning: Touching the electrical parts may be fatal – even after the equipment
has been disconnected from line power.
Also, make sure that other voltage inputs have been disconnected, such as
external 24 V DC, load sharing (linkage of DC intermediate circuit), as well
as the motor connection for kinetic backup. Refer to VLT® HVAC Drive
Instruction Manual MG.11.Ax.yy for further safety guidelines.
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2 Introduction to the VLT HVAC Drive
VLT® HVAC Drive Design Guide
2.1.2 Caution
2
Caution
The adjustable frequency drive DC link capacitors remain charged after power
has been disconnected. To avoid the risk of electrical shock, disconnect the
adjustable frequency drive from the line power before performing maintenance
procedures. Wait at least as long as follows before servicing the adjustable
frequency drive:
Voltage 200-240 V 380-480 V
525-600 V
Minimum Waiting Time
4 min.
15 min.
20 min.
30 min.
1.5-5 hp [1.1-3.7 kW] 7.5-60 hp [5.5-45 kW]
150-300 hp [110-200 1.5-10 hp [1.1-7.5 kW] 15-125 hp [11-90 kW] kW]
1.5-10 hp [1.1-7.5 kW]
150-350 hp [110-250 450-750 hp [315-560
kW]
kW]
Be aware that there may be high voltage on the DC link even when the LEDs are turned off.
40 min.
350-600 hp [250-450 kW]
2.1.3 Disposal Instructions
Equipment containing electrical components may not be disposed of together with domestic waste. It must be collected separately as electrical and electronic waste according to local and currently valid legislation.
2.2 CE labeling
2.2.1 CE Conformity and Labeling
What is CE Conformity and Labeling? The purpose of CE labeling is to avoid
technical trade obstacles within the EFTA and the EU. The EU has introduced
the CE label as a simple way of showing whether a product complies with the
relevant EU directives. The CE label says nothing about the specifications or
quality of the product. Adjustable frequency drives are regulated by three EU
directives: The machinery directive (98/37/EEC) All machines with critical
moving parts are covered by the Machinery Directive of January 1, 1995. Since
an adjustable frequency drive is largely electrical, it does not fall under
the Machinery Directive. However, if an adjustable frequency drive is supplied
for use in a machine, we provide information on its safety aspects in the
manufacturer’s declaration. The low-voltage directive (73/23/EEC) Adjustable
frequency drives must be CE-labeled in accordance with the Low-voltage
Directive of January 1, 1997. The directive applies to all electrical
equipment and appliances used in the 50-1000 V AC and the 75-1500 V DC voltage
ranges. Danfoss uses CE labels in accordance with the directive and will issue
a declaration of conformity upon request.
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VLT® HVAC Drive Design Guide
2 Introduction to the VLT HVAC Drive
The EMC directive (89/336/EEC)
EMC is short for electromagnetic compatibility. The presence of electromagnetic compatibility means that the mutual interference between different
components/appliances does not affect the way the appliances work.
The EMC directive came into effect January 1, 1996. Danfoss uses CE labels in accordance with the directive and will issue a declaration of conformity
upon request. To carry out EMC-correct installation, see the instructions in this Design Guide. In addition, we specify the standards with which our products
comply. We offer the filters presented in the specifications and provide other types of assistance to ensure the optimum EMC result.
2
The adjustable frequency drive is most often used by professionals of the trade as a complex component forming part of a larger appliance, system or installation. It must be noted that the responsibility for the final EMC properties of the appliance, system or installation rests with the installer.
2.2.2 What Is Covered
The EU “Guidelines on the Application of Council Directive 89/336/EEC” outline
three typical situations of using an adjustable frequency drive. See below for
EMC coverage and CE labeling.
1. The adjustable frequency drive is sold directly to the end-consumer. For
example, it may be sold to a DIY market. The end-consumer is a layman. He
installs the adjustable frequency drive himself for use with a hobby machine,
a kitchen appliance, etc. For such applications, the adjustable frequency
drive must be CE-labeled in accordance with the EMC directive.
2. The adjustable frequency drive is sold for installation in a plant. The
plant is built up by professionals of the trade. It could be a production
plant or a heating/ventilation plant designed and installed by professionals
of the trade. Neither the adjustable frequency drive nor the finished plant
must be CE-labeled under the EMC directive. However, the unit must comply with
the basic EMC requirements of the directive. This is ensured by using
components, appliances and systems that are CE-labeled under the EMC
directive.
3. The adjustable frequency drive is sold as part of a complete system. The
system is being marketed as complete and could, for example, be an air-
conditioning system. The complete system must be CE-labeled in accordance with
the EMC directive. The manufacturer can ensure CElabeling under the EMC
directive either by using CE-labeled components or by testing the EMC of the
system. If he chooses to use only CElabeled components, he does not have to
test the entire system.
2.2.3 Danfoss VLT Adjustable Frequency Drive and CE Labeling
CE labeling is a positive feature when used for its original purpose, i.e. to
facilitate trade within the EU and EFTA.
However, CE labeling may cover many different specifications. Thus, you must
check what a given CE label specifically covers.
The covered specifications can be very different and a CE label may therefore
give the installer a false sense of security when using an adjustable
frequency drive as a component in a system or an appliance.
Danfoss CE labels the adjustable frequency drives in accordance with the low-
voltage directive. This means that if the adjustable frequency drive is
installed correctly, we guarantee compliance with the low-voltage directive.
Danfoss issues a declaration of conformity that confirms our CE labeling in
accordance with the low-voltage directive.
The CE label also applies to the EMC directive provided that the instructions
for EMC-correct installation and filtering are followed. On this basis, a
declaration of conformity in accordance with the EMC directive is issued.
The Design Guide offers detailed instructions for installation to ensure EMC-
correct installation. Furthermore, Danfoss specifies which our different
products comply with.
Danfoss gladly provides other types of assistance that can help you obtain the
best EMC result.
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VLT® HVAC Drive Design Guide
2.2.4 Compliance with EMC Directive 89/336/EEC
As mentioned, the adjustable frequency drive is mostly used by professionals of the trade as a complex component forming part of a larger appliance,
system or installation. It must be noted that the responsibility for the final EMC properties of the appliance, system or installation rests with the installer.
To assist the installer, Danfoss has prepared EMC installation guidelines for the Power Drive system. The standards and test levels stated for power drive
2
systems are complied with, provided that the EMC-correct instructions for installation are followed; see the section EMC Immunity.
2.3 Air humidity
2.3.1 Air Humidity
The adjustable frequency drive has been designed to meet the IEC/EN 60068-2-3
standard, EN 50178 pkt. 9.4.2.2 at 122°F [50°C].
2.4 Aggressive Environments
An adjustable frequency drive contains a large number of mechanical and
electronic components. All are vulnerable to environmental effects to some
extent.
The adjustable frequency drive should not be installed in environments with
airborne liquids, particles or gases capable of affecting and damaging the
electronic components. Failure to take the necessary protective measures
increases the risk of stoppages, thus reducing the life of the adjustable
frequency drive.
Liquids can be carried through the air and condense in the adjustable
frequency drive and may cause corrosion of components and metal parts. Steam,
oil and salt water may cause corrosion of components and metal parts. In such
environments, use equipment with enclosure rating IP 55. As an extra
protection, coated printet circuit boards can be ordered as an option.
Airborne particles such as dust may cause mechanical, electrical or thermal
failure in the adjustable frequency drive. A typical indicator of excessive
levels of airborne particles is the presence of dust particles around the
adjustable frequency drive fan. In very dusty environments, use equipment with
enclosure rating IP 55 or a cabinet for IP 00/IP 20/TYPE 1 equipment.
In environments with high temperatures and humidity, corrosive gases such as
sulfur, nitrogen and chlorine compounds will cause chemical processes on the
adjustable frequency drive components.
Such chemical reactions will rapidly affect and damage the electronic
components. In such environments, mount the equipment in a cabinet with fresh
air ventilation, keeping aggressive gases away from the adjustable frequency
drive. An extra protection in such areas is a coating of the printed circuit
boards, which can be ordered as an option.
NOTE! Mounting adjustable frequency drives in aggressive environments
increases the risk of stoppages and considerably reduces the life of the
drive.
Before installing the adjustable frequency drive, check the ambient air for
liquids, particles and gases. This is done by observing existing installations
in this environment. A typical indicator of harmful airborne liquids is the
presence of water or oil on metal parts, or the corrosion of metal parts.
Excessive dust particle levels are often found on installation cabinets and
existing electrical installations. One indicator of aggressive airborne gases
is the blackening of copper rails and cable ends on existing installations.
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VLT® HVAC Drive Design Guide
2 Introduction to the VLT HVAC Drive
2.5 Vibration and shock
The adjustable frequency drive has been tested according to the procedure based on the shown standards:
The adjustable frequency drive complies with requirements that exist for units mounted on the walls and floors of production premises, as well as in
2
panels bolted to walls or floors.
IEC/EN 60068-2-6: IEC/EN 60068-2-64:
Vibration (sinusoidal) – 1970 Vibration, broad-band random
2.6 Advantages
2.6.1 Why use an adjustable frequency drive for controlling fans and pumps?
An adjustable frequency drive takes advantage of the fact that centrifugal
fans and pumps follow the laws of proportionality for such fans and pumps. For
further information, see The Laws of Proportionality text.
2.6.2 The clear advantage – energy savings
The very clear advantage of using an adjustable frequency drive for
controlling the speed of fans or pumps lies in the electricity savings.
Compared to alternative control systems and technologies, an adjustable
frequency drive is the optimum energy control system for controlling fan and
pump systems.
2.6.3 Example of energy savings
As can be seen from the figure (the laws of proportionality), the flow is
controlled by changing the rpm. By reducing the rated speed by only 20%, the
flow is also reduced by 20%. This is because the flow is directly proportional
to the rpm. The consumption of electricity, however, is reduced by 50%. If the
system in question only needs to be able to supply a flow corresponding to
100% a few days each year, while the average is below 80% of the rated flow
for the remainder of the year, the amount of energy saved is even greater than
50%.
The laws of proportionality The figure below describes the dependence of flow, pressure and power consumption on rpm.
Q = Flow Q1 = Rated flow Q2 = Reduced flow
P = Power P1 = Rated power P2 = Reduced power
H = Pressure H1 = Rated pressure H2 = Reduced pressure
n = Speed regulation n1 = Rated speed n2 = Reduced speed
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2
VLT® HVAC Drive Design Guide
Flow :
Q1 Q2
=
n1 n2
( ) Pressure :
H1 H2
=
n1 2 n2
( ) Power :
P1 P2
=
n1 3 n2
2.6.4 Example with varying flow over 1 year
The example below is calculated on the basis of pump characteristics obtained
from a pump datasheet. The result obtained shows energy savings in excess of
50% at the given flow distribution over a year. The pay back period depends on
the price per kwh and the price of the adjustable frequency drive. In this
example, it is less than a year when compared with valves and constant speed.
2-6
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Pump characteristics
2 Introduction to the VLT HVAC Drive
Energy savings Pshaft=Pshaft output
2
Flow distribution over 1 year
m3/h
350 300 250 200 150 100
Distribution
%
Hours
5
438
15
1314
20
1752
20
1752
20
1752
20
1752
100
8760
Valve regulation
Power
Consumption
A1 – B1
kWh
42.5
18,615
38.5
50,589
35.0
61,320
31.5
55,188
28.0
49,056
23.0
40,296
275,064
Adjustable frequency drive control
Power
Consumption
A1 – C1
kWh
42.5
18,615
29.0
38,106
18.5
32,412
11.5
20,148
6.5
11,388
3.5
6,132
26,801
2.6.5 Better control
If an adjustable frequency drive is used for controlling the flow or pressure
of a system, improved control is obtained. An adjustable frequency drive can
vary the speed of the fan or pump, thereby obtaining variable control of flow
and pressure. Furthermore, an adjustable frequency drive can quickly adapt the
speed of the fan or pump to new flow or pressure conditions in the system.
Simple control of process (flow, level or pressure) utilizing the built-in PID
control.
2.6.6 Cos compensation
Generally speaking, an adjustable frequency drive with a cos of 1 provides
power factor correction for the cos of the motor, which means that there is no
need to make allowance for the cos of the motor when sizing the power factor
correction unit.
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VLT® HVAC Drive Design Guide
2.6.7 Star/delta starter or soft-starter not required
When larger motors are started, it is necessary in many countries to use equipment that limits the start-up current. In more traditional systems, a star/
2
delta starter or soft-starter is widely used. Such motor starters are not required if an adjustable frequency drive is used.
As illustrated in the figure below, an adjustable frequency drive does not consume more than rated current.
1 = VLT HVAC Drive 2 = Star/delta starter
3 = Soft-starter 4 = Start directly on line power
2.6.8 The cost of using an adjustable frequency drive is not significantly
high.
The example on the following page shows that a lot of extra equipment is not
required when an adjustable frequency drive is used. It is possible to
calculate the cost of installing the two different systems. In the example,
the two systems can be established at roughly the same price.
2.6.9 Without an adjustable frequency drive
The figure shows a fan system made in the traditional way.
D.D.C. V.A.V.
=
Direct Digital Control
=
Variable Air Volume
Sensor P
=
Pressure
E.M.S. Sensor T
= Energy Management system = Temperature
2-8
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2 Introduction to the VLT HVAC Drive
2
2.6.10 With an adjustable frequency drive
The figure shows a fan system controlled by adjustable frequency drives.
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2 Introduction to the VLT HVAC Drive
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2.6.11 Application examples
The next few pages give typical examples of applications within HVAC. If you
would like to receive further information about a given application, please
ask your Danfoss supplier for an information sheet that gives a full
description of the application.
2 Variable Air Volume Ask for The Drive to…Improving Variable Air Volume
Ventilation Systems MN.60.A1.02
Constant Air Volume Ask for The Drive to…Improving Constant Air Volume
Ventilation Systems MN.60.B1.02
Cooling Tower Fan Ask for The Drive to…Improving Fan Control on Cooling Towers
MN.60.C1.02
Condenser pumps Ask for The Drive to…Improving Condenser Water Pumping Systems
MN.60.F1.02
Primary pumps Ask for The Drive to…Improve Your Primary Pumping in
Primary/Secondary Pumping Systems MN.60.D1.02
Secondary pumps Ask for The Drive to…Improve Your Secondary Pumping in
Primary/Secondary Pumping Systems MN.60.E1.02
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2 Introduction to the VLT HVAC Drive
2.6.12 Variable Air Volume
VAV or Variable Air Volume systems, are used to control both the ventilation and temperature to satisfy the requirements of a building. Central VAV
systems are considered to be the most energy efficient method to air condition buildings. By designing central systems instead of distributed systems,
greater efficiency can be obtained.
This greater efficiency is a result of utilizing larger fans and larger chillers, which have much higher efficiency rates than small motors and distributed air-
2
cooled chillers. Savings are also a result of decreased maintenance requirements.
2.6.13 The VLT solution
While dampers and IGVs work to maintain a constant pressure in the ductwork,
an adjustable frequency drive solution saves much more energy and reduces the
complexity of the installation. Instead of creating an artificial pressure
drop or causing a decrease in fan efficiency, the adjustable frequency drive
decreases the speed of the fan to provide the flow and pressure required by
the system. Centrifugal devices such as fans behave according to the
centrifugal laws. This means the fans decrease the pressure and flow they
produce as their speed is reduced. Their power consumption is thereby
significantly reduced. The return fan is frequently controlled to maintain a
fixed difference in airflow between the supply and return. The advanced PID
controller of the VLT HVAC Drive can be used to eliminate the need for
additional controllers.
Cooling coil
Heating coil
Filter
D1
D2
D3
Pressure signal
Supply fan
3
VAV boxes T
Pressure Flow transmitter
Return fan
3
Flow
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2.6.14 Constant Air Volume
CAV, or Constant Air Volume systems, are central ventilation systems usually used to supply large common zones with the minimum amounts of fresh
tempered air. They preceded VAV systems and therefore are found in older, multi-zoned commercial buildings as well. These systems preheat certain
amounts of fresh air utilizing Air Handling Units (AHUs) with a heating coil, and many are also used to air condition buildings and have a cooling coil. Fan
2
coil units are frequently used to assist in the heating and cooling requirements in the individual zones.
2.6.15 The VLT solution
With an adjustable frequency drive, significant energy savings can be obtained
while maintaining decent control of the building. Temperature sensors or CO2
sensors can be used as feedback signals to adjustable frequency drives.
Whether controlling temperature, air quality, or both, a CAV system can be
controlled to operate based on actual building conditions. As the number of
people in the controlled area decreases, the need for fresh air decreases. The
CO2 sensor detects lower levels and decreases the speed of the supply fans.
The return fan modulates to maintain a static pressure setpoint or fixed
difference between the supply and return air flows.
With temperature control (especially used in air conditioning systems), as the outside temperature varies and the number of people in the controlled zone changes, different cooling requirements arise. As the temperature decreases below the setpoint, the supply fan can decrease its speed. The return fan modulates to maintain a static pressure setpoint. By decreasing the air flow, energy used to heat or cool the fresh air is also reduced, adding further savings. Several features of the Danfoss HVAC dedicated adjustable frequency drive, the VLT® HVAC Drive can be utilized to improve the performance of your CAV system. One concern of controlling a ventilation system is poor air quality. The programmable minimum frequency can be set to maintain a minimum amount of supply air, regardless of the feedback or reference signal. The adjustable frequency drive also includes a 3-zone, 3-setpoint PID controller which allows monitoring of both temperature and air quality. Even if the temperature requirement is satisfied, the drive will maintain enough supply air to satisfy the air quality sensor. The controller is capable of monitoring and comparing two feedback signals to control the return fan by maintaining a fixed differential air flow between the supply and return ducts as well.
Cooling coil
Heating coil
Filter
D1
D2
D3
Temperature signal Supply fan
Pressure signal Return fan
Temperature transmitter
Pressure transmitter
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2 Introduction to the VLT HVAC Drive
2.6.16 Cooling Tower Fan
Cooling tower fans are used to cool condenser water in water-cooled chiller systems. Water-cooled chillers provide the most efficient means of creating
chilled water. They are as much as 20% more efficient than air-cooled chillers. Depending on climate, cooling towers are often the most energy efficient
method of cooling the condenser water from chillers.
They cool the condenser water by evaporation.
2
The condenser water is sprayed into the cooling tower, onto the cooling tower’s “fill” to increase its surface area. The tower fan blows air through the
fill and sprays water to aid in the evaporation. Evaporation removes energy from the water, thus dropping its temperature. The cooled water collects in
the cooling towers basin, where it is pumped back into the chiller’s condenser, and the cycle is then repeated.
2.6.17 The VLT solution
With an adjustable frequency drive, the cooling towers fans can be set to the
speed required to maintain the condenser water temperature. The adjustable
frequency drives can also be used to turn the fan on and off as needed.
Several features of the Danfoss HVAC dedicated drive, the VLT HVAC Drive can
be utilized to improve the performance of your cooling tower fan application.
As the cooling tower fans drop below a certain speed, the effect the fan has
on cooling the water becomes insignificant. Also, when utilizing a gear-box to
frequency control the tower fan, a minimum speed of 40-50% may be required.
The customer programmable minimum frequency setting is available to maintain
this minimum frequency even as the feedback or speed reference calls for lower
speeds.
Another standard feature is the “sleep” mode, which allows the user to program
the adjustable frequency drive to stop the fan until a higher speed is
required. Additionally, some cooling tower fans have undesireable frequencies
that may cause vibrations. These frequencies can easily be avoided by
programming the bypass frequency ranges in the adjustable frequency drive.
Water Inlet
BASIN
Temperature Sensor
Water Outlet
Conderser Water pump
CHILLER
Supply
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VLT® HVAC Drive Design Guide
2.6.18 Condenser pumps
Condenser water pumps are primarily used to circulate water through the
condenser section of water cooled chillers and their associated cooling tower.
The condenser water absorbs the heat from the chiller’s condenser section and
releases it into the atmosphere in the cooling tower. These systems are used
to provide the most efficient means of creating chilled water, and they are as
much as 20% more efficient than air cooled chillers.
2
2.6.19 The VLT solution
Adjustable frequency drives can be added to condenser water pumps instead of
balancing the pumps with a throttling valve or trimming the pump impeller.
Using an adjustable frequency drive instead of a throttling valve simply saves
the energy that would have been absorbed by the valve. This can amount to
savings of 15-20% or more. Trimming the pump impeller is irreversible, thus if
the conditions change and higher flow is required the impeller must be
replaced.
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2 Introduction to the VLT HVAC Drive
2.6.20 Primary pumps
Primary pumps in a primary/secondary pumping system can be used to maintain a constant flow through devices that encounter operation or control
difficulties when exposed to variable flow. The primary/secondary pumping technique decouples the “primary” production loop from the “secondary”
distribution loop. This allows devices such as chillers to obtain constant design flow and operate properly while allowing the rest of the system to vary in
flow.
2
As the evaporator flow rate decreases in a chiller, the chilled water begins to become overly chilled. As this happens, the chiller attempts to decrease its cooling capacity. If the flow rate drops far enough, or too quickly, the chiller cannot shed its load sufficiently and the chiller’s low evaporator temperature safety trips the chiller, requiring a manual reset. This situation is common in large installations, especially when two or more chillers are installed in parallel and primary/secondary pumping is not utilized.
2.6.21 The VLT solution
Depending on the size of the system and the size of the primary loop, the
energy consumption of the primary loop can become substantial. An adjustable
frequency drive can be added to the primary system to replace the throttling
valve and/or trimming of the impellers, leading to reduced operating expenses.
Two control methods are common:
The first method uses a flow meter. Because the desired flow rate is known and
constant, a flow meter installed at the discharge of each chiller can be used
to control the pump directly. Using the built-in PID controller, the
adjustable frequency drive will always maintain the appropriate flow rate,
even compensating for the changing resistance in the primary piping loop as
chillers and their pumps are staged on and off.
The other method is local speed determination. The operator simply decreases
the output frequency until the design flow rate is achieved.
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VLT® HVAC Drive Design Guide
Using a adjustable frequency drive to decrease the pump speed is very similar to trimming the pump impeller, except it doesn’t require any labor and
the pump efficiency remains higher. The balancing contractor simply decreases the speed of the pump until the proper flow rate is achieved and leaves
the speed fixed. The pump will operate at this speed any time the chiller is staged on. Because the primary loop doesn’t have control valves or other
devices that can cause the system curve to change, and because the variance due to staging pumps and chillers on and off is usually small, this fixed
speed will remain appropriate. In the event the flow rate needs to be increased later in the systems life, the adjustable frequency drive can simply increase
2
the pump speed instead of requiring a new pump impeller.
Flowmeter
F
Flowmeter
F
CHILLER CHILLER
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2 Introduction to the VLT HVAC Drive
2.6.22 Secondary pumps
Secondary pumps in a primary/secondary chilled water pumping system are used to distribute the chilled water to the loads from the primary production
loop. The primary/secondary pumping system is used to hydraulically decouple one piping loop from another. In this case, the primary pump is used to
maintain a constant flow through the chillers while allowing the secondary pumps to vary in flow, increase control and save energy.
If the primary/secondary design concept is not used and a variable volume system is designed, the chiller cannot shed its load properly when the flow
2
rate drops far enough or too quickly. The chiller’s low evaporator temperature safety then trips the chiller, requiring a manual reset. This situation is
common in large installations, especially when two or more chillers are installed in parallel.
2.6.23 The VLT solution
While the primary-secondary system with two-way valves improves energy savings
and eases system control problems, the true energy savings and control
potential is realized by adding adjustable frequency drives. With the proper
sensor location, the addition of adjustable frequency drives allows the pumps
to vary their speed to follow the system curve instead of the pump curve. This
results in the elimination of wasted energy and eliminates most of the over-
pressurization to which two-way valves can be subjected. As the monitored
loads are reached, the two-way valves close down. This increases the
differential pressure measured across the load and two-way valve. As this
differential pressure starts to rise, the pump is slowed to maintain the
control head also called setpoint value. This setpoint value is calculated by
adding the pressure drop of the load and the two-way valve under design
conditions.
NOTE! Please note that when running multiple pumps in parallel, they must run at the same speed to maximize energy savings, either with individual dedicated drives or one drive running multiple pumps in parallel.
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2.7 VLT HVAC Controls
2.7.1 Control Principle
2
An adjustable frequency drive rectifies AC voltage from line into DC voltage, after which DC voltage is converted into an AC current with a variable
amplitude and frequency.
The motor is supplied with variable voltage / current and frequency, which enables infinitely variable speed control of three-phased, standard AC motors.
2.7.2 Control Structure
Control structure in open-loop and closed-loop configurations:
In the configuration shown in the illustration above, par. 1-00 is set to
Open-loop [0]. The resulting reference from the reference handling system is
received and fed through the ramp limitation and speed limitation before being
sent to the motor control. The output of the motor control is then limited by
the maximum frequency limit.
Select Closed-loop [3] in par. 1-00 to use the PID controller for closed-loop
control of, e.g., flow, level or pressure in the controlled application. The
PID parameters are located in par. group 20-**.
2.7.3 Local (Hand On) and Remote (Auto On) Control
The adjustable frequency drive can be operated manually via the local control
panel (LCP) or remotely via analog and digital inputs and serial bus. If
allowed in par. 0-40, 0-41, 0-42, and 0-43, it is possible to start and stop
the adjustable frequency drive via the LCP using the [Hand ON] and [Off] keys.
Alarms can be reset via the [RESET] key. After pressing the [Hand On] key, the
adjustable frequency drive goes into hand mode and follows (as default) the
local reference set by using the LCP arrow keys.
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2 Introduction to the VLT HVAC Drive
After pressing the [Auto On] key, the adjustable frequency drive goes into auto mode and follows (as default) the remote reference. In this mode, it is possible to control the adjustable frequency drive via the digital inputs and various serial interfaces (RS-485, USB, or an optional serial communication bus). See more about starting, stopping, changing ramps and parameter set-ups, etc. in par. group 5-1 (digital inputs) or par. group 8-5 (serial communication).
130BP046.10
2
Active Reference and Configuration Mode
The active reference can be either the local reference or the remote
reference.
In par. 3-13 Reference Site, the local reference can be permanently selected
by selecting Local [2]. To permanently select the remote reference, select
Remote [1]. By selecting Linked to Hand/Auto [0] (default), the reference site
will depend on which mode is active. (Hand Mode or Auto Mode).
Hand Off Auto LCP Keys Hand Hand -> Off Auto Auto -> Off All keys All keys
Reference Site Par. 3-13
Linked to Hand/Auto Linked to Hand/Auto Linked to Hand/Auto Linked to
Hand/Auto Local Remote
Active Reference
Local Local Remote Remote Local Remote
The table shows under which conditions either the local reference or the remote reference is active. One of them is always active, but both cannot be active at the same time.
Par. 1-00 Configuration Mode determines what kind of application control principle (i.e., open-loop or closed-loop) is used when the remote reference is active (see table above for the conditions).
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2 Introduction to the VLT HVAC Drive
Reference Handling – Local Reference
2
VLT® HVAC Drive Design Guide
2.8 PID
2.8.1 Closed-loop (PID) Controller
The drive’s closed-loop controller allows the drive to become an integral part
of the controlled system. The drive receives a feedback signal from a sensor
in the system. It then compares this feedback to a setpoint reference value
and determines the error, if any, between these two signals. It then adjusts
the speed of the motor to correct this error.
For example, consider a ventilation system where the speed of the supply fan
is to be controlled so that the static pressure in the duct is constant. The
desired static pressure value is supplied to the drive as the setpoint
reference. A static pressure sensor measures the actual static pressure in the
duct and supplies this to the drive as a feedback signal. If the feedback
signal is greater than the setpoint reference, the drive will slow down to
reduce the pressure. In a similar way, if the duct pressure is lower than the
setpoint reference, the drive will automatically speed up to increase the
pressure provided by the fan.
NOTE! While the default values for the drive’s closed-loop controller will
often provide satisfactory performance, the control of the system can often be
optimized by adjusting some of the closed-loop controller’s parameters.
The figure is a block diagram of the drive’s closed-loop controller. The
details of the reference handling block and feedback handling block are
described in their respective sections below.
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2 Introduction to the VLT HVAC Drive
The following parameters are relevant for a simple PID control application:
Parameter
Description of function
Feedback 1 Source
par. 20-00
Select the source for Feedback 1. This is most commonly an analog input, but other sources are
also available. Use the scaling of this input to provide the appropriate values for this signal. By default, Analog Input 54 is the default source for Feedback 1.
2
Reference/Feedback Unit
par 20-12
Select the unit for the setpoint referenceand feedback for the drive’s closed- loop controller. Note:
Because a conversion can be applied to the feedback signal before it is used by the closed-loop
controller, the reference/feedback unit (par. 20-12) may not be the same as the feedback source
unit (par. 20-02, 20-05 and 20-08).
PID Normal/Inverse Control par. 20-81
Select Normal [0] if the motor’s speed should decrease when the feedback is greater than the
setpoint reference. Select Inverse [1] if the motor’s speed should increase when the feedback
is greater than the setpoint reference.
PID Proportional Gain
par. 20-93
This parameter adjusts the output of the drive’s closed-loop control based on the error between
the feedback and the setpoint reference. Quick controller response is obtained when this value
is large. However, if a value that is too large is used, the drive’s output frequency may become
unstable.
PID Integral Time
par. 20-94
Over time, the integrator adds (integrates) the error between the feedback and the setpoint
reference. This is required to ensure that the error approaches zero. Quick controller response
is obtained when this value is small. However, if a value that is too small is used, the drive’s
output frequency may become unstable. A setting of 10,000 s disables the integrator.
This table summarizes the parameters that are needed to set up the drive’s closed-loop controller when a single feedback signal with no conversion is compared to a single setpoint. This is the most common type of closed-loop controller.
2.8.2 Closed-loop Control Relevant Parameters
The drive’s closed-loop controller is capable of handling more complex
applications, such as situations where a conversion function is applied to the
feedback signal or situations where multiple feedback signals and/or setpoint
references are used. The table below summarizes the additional parameters that
may be useful in such applications.
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Parameter Feedback 2 Source Feedback 3 Source
2
Feedback 1 Conversion
Feedback 2 Conversion
Feedback 3 Conversion
Feedback 1 Source Unit Feedback 2 Source Unit Feedback 3 Source Unit Feedback Function
Setpoint 1 Setpoint 2 Setpoint 3 Refrigerant
par. 20-03 par. 20-06
par. 20-01 par. 20-04 par. 20-07
par. 20-02 par. 20-05 par. 20-08 par. 20-20
par. 20-21 par. 20-22 par. 20-23 par. 20-30
Description of function Select the source, if any, for Feedback 2 or 3. This is most commonly a drive analog input, but other sources are also available. Par. 20-20 determines how multiple feedback signals will be processed by the drive’s closed-loop controller. By default, these are set to No function [0]. These are used to convert the feedback signal from one type to another, for example from pressure to flow or from pressure to temperature (for compressor applications). If Pressure to temperature [2] is selected, the refrigerant must be specified in par. Group 20-3, Feedback Adv. Conv. By default, these are set to Linear [0]. Select the unit for a feedback source prior to any conversions. This is used for display purposes only. This parameter is only available when using Pressure to Temperature feedback conversion. When multiple feedbacks or setpoints are used, this determines how they will be processed by the drive’s closed-loop controller. These setpoints can be used to provide a setpoint reference to the drive’s closed-loop controller. Par. 20-20 determines how multiple setpoint references will be processed. Any other references that are activated in par. group 3-1 will add to these values. If any feedback conversion (par. 20-01, 20-04 or 20-07) is set to Pressure to Temperature [2], the refrigerant type must be selected here. If the refrigerant used is not listed here, select User defined [7] and specify the characteristics of the refrigerant in par. 20-31, 20-32 and 20-33.
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2 Introduction to the VLT HVAC Drive
Parameter Custom Refrigerant A1 Custom Refrigerant A2 Custom Refrigerant A3
PID Start Speed [RPM] PID Start Speed [Hz] On Reference Bandwidth PID Anti
Windup
PID Differentiation Time
PID Diff. Gain Limit
Low-pass Filter Time: Analog Input 53 Analog Input 54 Digital (pulse) input 29
Digital (pulse) input 33
Description of function
par. 20-31
When par. 20-30 is set to User defined [7], these parameters are used to define the
par. 20-32
value of coefficients A1, A2 and A3 in the conversion equation:
par. 20-33
Temperature
=
A2 (ln(pressure + 1) – A1)
– A3
par. 20-82
The parameter that is visible will depend on the setting of par. 0-02, Motor Speed Unit.
2
par. 20-83
In some applications, and after a start command, it is important to quickly ramp the
motor up to a pre-determined speed before activating the drive’s closed-loop controller.
This parameter defines that starting speed.
par. 20-84
This determines how close the feedback must be to the setpoint reference for the drive
to indicate that the feedback is equal to the setpoint.
par. 20-91
On [1] effectively disables the closed-loop controller’s integral function when it is not
possible to adjust the output frequency of the drive to correct the error. This allows the
controller to respond more quickly once it can again control the system. Off [0] disables
this function, making the integral function stay active continuously.
par. 20-95
This controls the output of the drive’s closed-loop controller based on the rate of change
of feedback. While this can provide fast controller response, such response is seldom
needed in HVAC systems. The default value for this parameter is Off, or 0.00 s.
par. 20-96
Because the differentiator responds to the rate of change of the feedback, a rapid
change can cause a large, undesired change in the output of the controller. This is used
to limit the maximum effect of the differentiator. This is not active when par. 20-95 is
set to Off.
par. 6-16
This is used to filter out high frequency noise from the feedback signal. The value en-
par. 6-26
tered here is the time constant for the low-pass filter. The cut-off frequency in Hz can
par. 5-54
be calculated as follows:
par. 5-59
Fcut-off
=
1 2T low-pass
Variations in the feedback signal whose frequency is below Fcut-off will be used by the
drive’s closed-loop controller, while variations at a higher frequency are considered to
be noise and will be attenuated. Large values of Low-pass Filter Time will provide more
filtering, but may cause the controller to not respond to actual variations in the feedback
signal.
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2 Introduction to the VLT HVAC Drive 2.8.3 Example of Closed-loop PID Control
The following is an example of a closed-loop control for a ventilation system:
2
VLT® HVAC Drive Design Guide
In a ventilation system, the temperature is to be maintained at a constant
value. The desired temperature is set between 23° and 95° F [-5° and +35° C]
using a 0-10 volt potentiometer. Because this is a cooling application, if the
temperature is above the setpoint value, the speed of the fan must be
increased to provide more cooling air flow. The temperature sensor has a range
of 14° to 104° F [-10° to +40° C] and uses a two-wire transmitter to provide a
4-20 mA signal. The output frequency range of the drive is 10 to 50 Hz.
1. Start/Stop via switch connected between terminals 12 (+24 V) and 18. 2.
Temperature reference via a potentiometer (23°- 95° F [-5° to +35°
C], 0 10 V) connected to terminals 50 (+10 V), 53 (input) and 55 (common). 3.
Temperature feedback via transmitter (14°-104° F [-10° – +40° C], 4-20 mA)
connected to terminal 54. Switch S202 behind the local control panel set to ON
(current input).
2-24
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VLT® HVAC Drive Design Guide
2 Introduction to the VLT HVAC Drive
2.8.4 Programming Order
Function
Par. no.
Setting
- Make sure the motor runs properly. Do the following:
Set the drive to control the motor based on drive out- 0-02
Hz [1]
put frequency. Set the motor parameters using nameplate data.
1-2*
As specified by motor nameplate
2
Run Automatic Motor Adaptation.
1-29
Enable complete AMA [1] and then run the AMA
function.
- Make sure that the motor is running in the right direction.
Pressing [Hand On] starts the motor at 5 Hz in for-
If motor rotation direction is incorrect, two motor
ward direction, and the display shows: “Motor is run-
phase cables should be interchanged.
ning. Check if motor rotation direction is correct.
- Make sure the adjustable frequency drive limits are set to safe values.
Make sure that the ramp settings are within the ca- 3-41
60 sec.
pabilities of the drive and the allowed application 3-42
60 sec.
operating specifications.
Depends on motor/load size!
Also active in hand mode.
Prohibit the motor from reversing (if necessary)
4-10
Clockwise [0]
Set acceptable limits for the motor speed.
4-12
10 Hz
4-14
50 Hz
4-19
50 Hz
Switch from open-loop to closed-loop.
1-00
Closed-loop [3]
- Configure the feedback to the PID controller.
Set up Analog Input 54 as a feedback input.
20-00
Analog input 54 [2] (default)
Select the appropriate reference/feedback unit.
20-12
°C [60]
- Configure the setpoint reference for the PID controller.
Set acceptable limits for the setpoint reference.
3-02
23°F [-5°C]
3-03
95°F [35°C]
Set up Analog Input 53 as Reference 1 Source.
3-15
Analog input 53 [1] (default)
- Scale the analog inputs used for setpoint reference and feedback.
Scale Analog Input 53 for the temperature range of 6-10
0 V
the potentiometer (23°-95°F [-5°-+35°C], 0-10 V). 6-11
10 V (default)
6-14
23°F [-5°C]
6-15
95°F [35°C]
Scale Analog Input 54 for the temperature range of 6-22
4 mA
the temperature sensor (-14° – +104°F [-10° –
6-23
20 mA (default)
+40°C], 4-20 mA)
6-24
14°F [-10°C]
6-25
104°F [40°C]
- Tune the PID controller parameters.
Select inverse control, because the motor’s speed 20-81
Inverse [1]
should increase when the feedback is greater than
the setpoint reference.
Adjust the drive’s closed-loop controller, if needed. 20-93
See Optimization of the PID Controller below.
20-94
- Finished!
Save the parameter settings to the LCP for safekeep- 0-50
All to LCP [1]
ing.
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2-25
2 Introduction to the VLT HVAC Drive
VLT® HVAC Drive Design Guide
2.8.5 Tuning the Drive Closed-loop Controller
Once the drive’s closed-loop controller has been set up, the performance of the controller should be tested. In many cases, its performance may be
acceptable using the default values of PID Proportional Gain (par. 20-93) and PID Integral Time (par. 20-94). However, in some cases it may be helpful
to optimize these parameter values to provide faster system response while still controlling speed overshoot. In many situations, this can be done by
2
following the procedure below:
1. Start the motor.
2. Set par. 20-93 (PID Proportional Gain) to 0.3 and increase it until the
feedback signal begins to oscillate. If necessary, start and stop the drive,
or make step changes in the setpoint reference to attempt to cause
oscillation. Next, reduce the PID Proportional Gain until the feedback signal
stabilizes. Then reduce the proportional gain by 40-60%.
3. Set par. 20-94 (PID Integral Time) to 20 sec. and reduce it until the
feedback signal begins to oscillate. If necessary, start and stop the drive,
or make step changes in the setpoint reference to attempt to cause
oscillation. Next, increase the PID Integral Time until the feedback signal
stabilizes. Then increase the Integral Time by 15-50%.
4. Par. 20-95 (PID Differentiation Time) should only be used for very fast-
acting systems. The typical value is 25% of the PID Integral Time (par.
20-94). The differentiator should only be used when the setting of the
proportional gain and the integral time has been fully optimized. Make sure
that oscillations of the feedback signal are sufficiently dampened by the low-
pass filter for the feedback signal (par 6 16, 6 26, 5 54 or 5 59, as
required).
2.8.6 Ziegler Nichols Tuning Method
In general, the above procedure is sufficient for HVAC applications. However,
other, more sophisticated procedures can also be used. The Ziegler Nichols
tuning method is a technique that was developed in the 1940s and is still
commonly used today. It generally provides acceptable control performance
using a simple experiment and parameter calculation.
NOTE! This method must not be used on applications that could be damaged by oscillations created by marginally stable control settings.
Figure 2.1: Marginally stable system
1. Select proportional control only. That is, PID Integral Time (par. 20-94)
is set to Off (10,000 s), and the PID Differentiation Time (par. 20-95) is
also set to Off (0 s in this case).
2. Increase the value of the PID Proportional Gain (par 20-93) until the
point of instability is reached, as indicated by sustained oscillations of the
feedback signal. The PID Proportional Gain that causes sustained oscillations
is called the critical gain, Ku.
3. Measure the period of oscillation, Pu. NOTE: Pu should be measured when
the amplitude of oscillation is relatively small. The output must not saturate
(i.e., the maximum or minimum feedback signal must not be reached during the
test).
4. Use the table below to calculate the necessary PID control parameters.
2-26
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VLT® HVAC Drive Design Guide
2 Introduction to the VLT HVAC Drive
Type of Control PI-control PID tight control PID some overshoot
Proportional Gain 0.45 Ku 0.6 Ku 0.33 * Ku
Integral Time 0.833 Pu 0.5 Pu 0.5 * Pu
Differentiation Time 0.125 Pu 0.33 Pu
Ziegler Nichols tuning for regulator, based on a stability boundary
2
Experience has shown that the control setting according to the Ziegler Nichols rule provides a good closed-loop response for many systems. If necessary,
the operator can perform the final tuning of the control iteratively in order to modify the response of the control loop.
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2-27
2 Introduction to the VLT HVAC Drive 2.8.7 Reference Handling
A block diagram of how the drive produces the remote reference is shown below.
2
VLT® HVAC Drive Design Guide
The Remote Reference is comprised of: · Preset references. · External
references (analog inputs, pulse frequency inputs, digital potentiometer
inputs and serial communication bus references).
· The preset relative reference. · Feedback controlled setpoint. Up to 8
preset references can be programmed in the drive. The active preset reference
can be selected using digital inputs or the serial communications bus. The
reference can also be supplied externally, most commonly from an analog input.
This external source is selected by one of the 3 reference source parameters
(par. 3-15, 3-16 and 3-17). Digipot is a digital potentiometer. This is also
commonly called a speed up/slow control, or a floating point control. To set
it up, one digital input is programmed to increase the reference, while
another digital input is programmed to decrease the reference. A
2-28
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VLT® HVAC Drive Design Guide
2 Introduction to the VLT HVAC Drive
third digital input can be used to reset the digipot reference. All reference resources and the bus reference are added to produce the total external reference. The external reference, the preset reference or the sum of the two can be selected to be the active reference. Finally, this reference can be scaled by using the preset relative reference (par. 3-14).
The scaled reference is calculated as follows:
( ) Reference = X + X ×
Y 100
2
Where X is the external reference, the preset reference or the sum of these, and Y is the preset relative reference (par. 3-14) in [%].
NOTE! If Y, the preset relative reference (par. 3-14), is set to 0%, the reference will not be affected by the scaling
2.8.8 Feedback Handling
A block diagram of how the drive processes the feedback signal is shown below.
Feedback handling can be configured to work with applications requiring
advanced control, such as multiple setpoints and multiple feedbacks. Three
types of control are common.
Single Zone, Single Setpoint Single Zone, Single Setpoint is a basic
configuration. Setpoint 1 is added to any other reference (if any, see
Reference Handling), and the feedback signal is selected using par. 20-20.
Multi-zone, Single Setpoint Multi-zone, Single Setpoint uses two or three
feedback sensors, but only one setpoint. The feedbacks can be added,
subtracted (only feedback 1 and 2) or averaged. In addition, the maximum or
minimum value may be used. Setpoint 1 is used exclusively in this
configuration.
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2-29
2 Introduction to the VLT HVAC Drive
VLT® HVAC Drive Design Guide
Multi-zone, Multi-setpoint applies an individual setpoint reference to each feedback. The drive’s closed-loop controller chooses one pair to control the drive based on the user’s selection in par. 20-20. If Multi-setpoint Max [14] is selected, the setpoint/feedback pair with the smallest difference controls the drive’s speed. (Note that a negative value is always smaller than a positive value).
2
If Multi-setpoint Min [13] is selected, the setpoint/feedback pair with the largest difference controls the speed of the drive. Multi-setpoint Maximum [14]
attempts to keep all zones at or below their respective setpoints, while Multi-setpoint Min [13] attempts to keep all zones at or above their respective
setpoints.
Example: The setpoint of a two-zone, two-setpoint application, Zone 1, is 64° F [18° C], while the feedback is 66° F [19° C]. Zone 2 setpoint is 71° F [22° C] and the feedback is 68° F [20° C]. If Multi-setpoint Max [14] is selected, the setpoint and feedback of Zone 1 are sent to the PID controller, since this has the smaller difference (feedback is higher than setpoint, resulting in a negative difference). If Multi-setpoint Max [13] is selected, the setpoint and feedback of Zone 2 are sent to the PID controller, since this has the larger difference (feedback is lower than setpoint, resulting in a positive difference).
2.8.9 Feedback Conversion
In some applications, it may be useful to convert the feedback signal. One
example of this is using a pressure signal to provide flow feedback. Since the
square root of pressure is proportional to flow, the square root of the
pressure signal yields a value proportional to the flow. This is shown below.
Another application that may benefit from feedback conversion is compressor control. In such applications, the output of a pressure sensor may be
converted to the refrigerant temperature using the equation:
Temperature
=
A2 (ln(pressure + 1) – A1)
– A3
where A1, A2 and A3 are refrigerant-specific constants.
2-30
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VLT® HVAC Drive Design Guide
2 Introduction to the VLT HVAC Drive
2.9 General aspects of EMC
2.9.1 General Aspects of EMC Emissions
Electrical interference is usually conducted at frequencies in the range of 150 kHz to 30 MHz. Airborne interference from the drive system in the range
2
of 30 MHz to 1 GHz is generated from the inverter, motor cable and motor.
As shown in the illustration below, capacitive currents in the motor cable coupled with a high dV/dt from the motor voltage generate leakage currents.
The use of a shielded motor cable increases the leakage current (see illustration below), because shielded cables have higher capacitance to ground than
non-shielded cables. If the leakage current is not filtered, it will cause greater interference on the line power supply in the radio frequency range below
approximately 5 MHz. Because the leakage current (I1) is carried back to the unit through the shield (I 3), there will in principle only be a small electro-
magnetic field (I4) from the shielded motor cable according to the below figure.
The shield reduces the radiated interference, but increases the low-frequency interference in the line power supply. The motor cable shield must be connected to the adjustable frequency drive enclosure as well as on the motor enclosure. This is best done by using integrated shield clamps so as to avoid twisted shield ends (pigtails). These increase the shield impedance at higher frequencies, which reduces the shield effect and increases the leakage current (I4). If a shielded cable is used for the serial communication bus, relay, control cable, signal interface and brake, the shield must be mounted on the enclosure at both ends. In some situations, however, it will be necessary to break the shield to avoid current loops.
If the shield is to be placed on a mounting plate for the adjustable frequency
drive, the mounting plate must be made of metal, because the shield currents
have to be conveyed back to the unit. Moreover, ensure good electrical contact
from the mounting plate through the mounting screws to the adjustable
frequency driver chassis.
NOTE! When non-shielded cables are used, some emission requirements are not
complied with, although the immunity requirements are observed.
In order to reduce the interference level from the entire system (unit +
installation), make motor and brake cables as short as possible. Avoid placing
cables with a sensitive signal level alongside motor and brake cables. Radio
interference higher than 50 MHz (airborne) is especially generated by the
control electronics.
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2-31
2 Introduction to the VLT HVAC Drive 2.9.2 EMC Test Results (Emission, Immunity)
VLT® HVAC Drive Design Guide
The following test results were obtained using a system with an adjustable frequency drive (with options, if rele-
vant), a shielded control cable, a control box with potentiometer, as well as a motor and motor-shielded cable.
2
RFI filter type
Conducted emission
Radiated emission
Industrial environment
Housing, Industrial envi- Housing, trades, and
trades, and
ronment
light industries
light industries
Set-up
EN 55011 EN 55011 EN 55011 EN 55011 Class EN 55011 Class B
Class A2
Class A1
Class B
A1
H1
1.4-60 hp [1.1-45 kW] 200-240 V
492 ft [150 m]
492 ft [150 m] 1)
164 ft [50 m]
Yes
No
1.5-125 hp [1.1-90 kW]
492 ft [150
380-480 V
492 ft [150 m]
m]
164 ft [50 m]
Yes
No
H2
1.5-5 hp [1.1-3.7 kW]
16 ft [5 m]
No
No
No
No
200-240 V
7.5-60 hp [5.5-45 kW]
200-240 V
82 ft [25 m]
No
No
No
No
1.5-10 hp [1.1-7.5 kW] 16 ft [5 m]
No
No
No
No
380-480 V
15-125 hp [11-90 kW]
380-480 V
82 ft [25 m]
No
No
No
No
150-600 hp [110-450 kW] 380-480
164 ft [50 m]
No
No
No
No
100-670 hp [75-500 kW] 525-600 V
492 ft [150 m]
No
No
No
No
H3
1.4-60 hp [1.1-45 kW]
200-240 V
75 m
50 m 1)
10 m
Yes
No
1.5-125 hp [1.1-90 kW] 380-480 V
75 m
164 ft [50 m]
10 m
Yes
No
H4
150-600 hp [110-450 kW] 380-480
492 ft [150 m]
45 m
No
Yes
No
100-450 hp [75-315 kW] 525-600 V
492 ft [150 m] 98 ft [30 m]
No
No
No
Hx
1.5-10 hp [1.1-7.5 kW]
525-600 V
–
–
–
–
–
Table 2.1: EMC Test Results (Emission, Immunity)
- 15 hp [11 kW] 200 V, H1 and H2 performance is delivered in enclosure type B1. 15 hp [11 kW] 200 V, H3 performance is delivered in enclosure type B2.
2.9.3 Required Compliance Levels
Standard / environment
IEC 61000-6-3 (generic) IEC 61000-6-4 EN 61800-3 (restricted) EN 61800-3
(unrestricted)
Housing, trades, and light industries
Conducted
Radiated
Class B
Class B
Class A1 Class B
Class A1 Class B
Industrial environment
Conducted
Radiated
Class A1 Class A1 Class A2
Class A1 Class A1 Class A2
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VLT® HVAC Drive Design Guide
2 Introduction to the VLT HVAC Drive
EN 55011:
Threshold values and measuring methods for radio interference from industrial, scientific and
medical (ISM) high-frequency equipment.
Class A1:
Equipment used in a public supply network. Restricted distribution.
Class A2:
Equipment used in a public supply network.
Class B1:
Equipment used in areas with a public supply network (residential, commerce, and light industries).
Unrestricted distribution.
2
2.9.4 EMC Immunity
In order to document immunity against interference from electrical phenomena,
the following immunity tests have been performed on a system consisting of an
adjustable frequency drive (with options, if relevant), a shielded control
cable and a control box with potentiometer, motor cable and motor.
The tests were performed in accordance with the following basic standards:
· EN 61000-4-2 (IEC 61000-4-2): Electrostatic discharges (ESD): Simulation of
electrostatic discharges from human beings. · EN 61000-4-3 (IEC 61000-4-3):
Incoming electromagnetic field radiation, amplitude modulated Simulation of
the effects of radar and radio
communication equipment, as well as mobile communications. · EN 61000-4-4 (IEC
61000-4-4): Electrical interference: Simulation of interference brought about
by switching with a contactor, relays or
similar devices. · EN 61000-4-5 (IEC 61000-4-5): Surge transients: Simulation
of transients brought about by lightning that strikes near installations
(e.g.). · EN 61000-4-6 (IEC 61000-4-6): RF Common mode: Simulation of the
effect from radio-transmitting equipment connected to cables. See following
EMC immunity form.
VLT HVAC; 200-240 V, 380-480 V Basic standard
Acceptance criterion Line
Motor Brake Load sharing Control wires Standard bus Relay wires Application
and serial communication options LCP cable External 24 V DC
Enclosure
AD: Air Discharge CD: Contact Discharge CM: Common mode DM: Differential mode
- Injection on cable shield
Table 2.2: Immunity
Burst IEC 61000-4-4
B
4 kV CM
4 kV CM 4 kV CM 4 kV CM 2 kV CM 2 kV CM 2 kV CM 2 kV CM
2 kV CM
2 kV CM
—
Surge IEC 61000-4-5
B 2 kV/2 DM 4 kV/12 CM
4 kV/2 1) 4 kV/2 1) 4 kV/2 1)
2 kV/2 1) 2 kV/2 1) 2 kV/2 1)
2 kV/2 1)
2 kV/2 1) 0.5 kV/2 DM 1 kV/12 CM
—
ESD IEC 61000-4-2
B
—
— — — — — —
—
—
—
8 kV AD 6 kV CD
Radiated electromagnetic field IEC 61000-4-3
A
—
— — — — — —
—
—
—
10 V/m
RF common mode voltage IEC 61000-4-6
A
10 VRMS
10 VRMS 10 VRMS 10 VRMS 10 VRMS 10 VRMS 10 VRMS
10 VRMS
10 VRMS
10 VRMS
—
2.10 Galvanic isolation (PELV)
PELV offers protection by way of extra low voltage. Protection against
electric shock is ensured when the electrical supply is of the PELV type and
the installation is made as described in local/national regulations on PELV
supplies.
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2 Introduction to the VLT HVAC Drive
VLT® HVAC Drive Design Guide
All control terminals and relay terminals 01-03/04-06 comply with PELV
(Protective Extra Low Voltage – does not apply to 525-600 V units and at
grounded Delta leg above 300 V).
Galvanic (ensured) isolation is obtained by fulfilling requirements for higher
isolation and by providing the relevant creepage/clearance distances. These
requirements are described in the EN 61800-5-1 standard.
2 The components that make up the electrical isolation, as described below,
also comply with the requirements for higher isolation and the relevant test
as described in EN 61800-5-1. The PELV galvanic isolation can be shown in six
locations (see illustration):
In order to maintain PELV, all connections made to the control terminals must
be PELV. For example, the thermistor must be reinforced/double insulated.
1. Power supply (SMPS) incl. signal isolation of UDC, indicating the
intermediate current voltage. 2. Gate drive that runs the IGBTs (trigger
transformers/opto-couplers). 3. Current transducers. 4. Opto-coupler, brake
module. 5. Internal soft-charge, RFI and temperature measurement circuits. 6.
Custom relays.
Figure 2.2: Galvanic isolation
The functional galvanic isolation (a and b in drawing) is for the 24 V backup
option and for the RS-485 standard bus interface.
At altitudes higher than 6,600 feet [2 km], please contact Danfoss Drives
regarding PELV.
2.11 Ground leakage current
Warning: Touching the electrical parts may be fatal – even after the equipment
has been disconnected from line power. Make sure that other voltage inputs
have been disconnected, such as load-sharing (linkage of DC intermediate
circuit), as well as the motor connection for kinetic back-up. Before touching
any electrical parts, wait at least: Please consult the section
Safety>Caution. Shorter time than stated in the table is allowed only if
indicated on the nameplate for the specific unit.
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VLT® HVAC Drive Design Guide
2 Introduction to the VLT HVAC Drive
Leakage Current
The ground leakage current from the adjustable frequency drive exceeds 3.5 mA. To ensure that the ground cable has a good me-
chanical connection to the ground connection (terminal 95), the cable cross- section must be at least 0.016 in.2 [10 mm2] or have 2
rated ground wires terminated separately.
Residual Current Device
This product can cause DC current in the protective conductor. Where a residual current device (RCD) is used for extra protection, only
2
an RCD of Type B (time delayed) shall be used on the supply side of this product. See also RCD Application Note MN.90.Gx.yy.
Protective grounding of the adjustable frequency drive and the use of RCDs must always follow national and local regulations.
2.12 Control with brake function
2.12.1 Selection of Brake Resistor
In certain applications, such as in tunnels or underground railway station
ventilation systems, it is desirable to bring the motor to a stop more rapidly
than can be achieved through controlling via ramp-down or free-wheeling. In
such applications, dynamic braking with a braking resistor may be utilized.
Using a braking resistor ensures that the energy is absorbed in the resistor
and not in the adjustable frequency drive.
If the amount of kinetic energy transferred to the resistor in each braking
period is not known, the average power can be calculated on the basis of the
cycle time and braking time, also known as the intermitted duty cycle. The
resistor intermittent duty cycle is an indication of the duty cycle at which
the resistor is active. The figure below shows a typical braking cycle.
The intermittent duty cycle for the resistor is calculated as follows:
Duty Cycle = tb / T
T = cycle time in seconds tb is the braking time in seconds (as part of the
total cycle time)
Danfoss offers brake resistors with duty cycle of 5%, 10% and 40% suitable for
use with the VLT® FC102 HVAC drive series. If a 10% duty cycle resistor is
applied, it is capable of absorbing braking energy up to 10% of the cycle
time, with the remaining 90% being used to dissipate heat from the resistor.
For further selection advice, please contact Danfoss.
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2 Introduction to the VLT HVAC Drive
VLT® HVAC Drive Design Guide
NOTE! If a short circuit in the brake transistor occurs, power dissipation in
the brake resistor is only prevented by using a line switch or contactor to
disconnect the AC line for the adjustable frequency drive. (The contactor can
be controlled by the adjustable frequency drive).
2
2.12.2 Brake Resistor Calculation
The brake resistance is calculated as shown:
Rbr
=
U d2c Ppeak
where
Ppeak = Pmotor x Mbr x motor x VLT[W]
As can be seen, the brake resistance depends on the intermediate circuit voltage (UDC). The brake function of the adjustable frequency drive is settled in 3 areas of the line power supply:
Size 3 x 200-240 V 3 x 380-480 V 3 x 525-600 V
Brake active 390 V (UDC) 778 V 943 V
Warning before cut out Cut out (trip)
405 V
410 V
810 V
820 V
965 V
975 V
NOTE! Make sure that the brake resistor can cope with a voltage of 410 V, 820 V or 975 V – unless Danfoss brake resistors are used.
Danfoss recommends the brake resistance Rrec, i.e., one that guarantees that the adjustable frequency drive is able to brake at the highest braking torque (Mbr(%)) of 110%. The formula can be written as:
Rrec
=
U
2 dc
x
100
Pmotor x Mbr (%) x VLT x motor
motor is typically at 0.90
VLT is typically at 0.98
For 200 V, 480 V and 600 V adjustable frequency drives, Rrec at 160% braking torque is written as:
200V
:
Rrec
=
107780 Pmotor
480V
: Rrec =
375300 Pmotor
600V
: Rrec =
630137 Pmotor
-
For adjustable frequency drives 10 hp [7.5 kW) shaft output
-
For adjustable frequency drives > 10 hp [7.5 kW] shaft output
480V
: Rrec =
428914 Pmotor
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VLT® HVAC Drive Design Guide
2 Introduction to the VLT HVAC Drive
NOTE! The resistor brake circuit resistance selected should not be higher than that recommended by Danfoss. If a brake resistor with a higher ohmic value is selected, the braking torque may not be achieved because there is a risk that the adjustable frequency drive cuts out for safety reasons.
NOTE!
2
If a short circuit in the brake transistor occurs, power dissipation in the brake resistor is only prevented by using a line switch or
contactor to disconnect the AC line for the adjustable frequency drive. (The contactor can be controlled by the adjustable frequency
drive).
NOTE! Do not touch the brake resistor, as it can get very hot during/after braking.
2.12.3 Control with Brake Function
The brake is to limit the voltage in the intermediate circuit when the motor
acts as a generator. This occurs, for example, when the load drives the motor
and the power accumulates on the DC link. The brake is built up as a chopper
circuit with the connection of an external brake resistor.
Placing the brake resistor externally offers the following advantages: – The
brake resistor can be selected on the basis of the application in question. –
The braking energy can be dissipated outside the control panel, i.e., where
the energy can be utilized. – The electronics of the adjustable frequency
drive will not overheat if the brake resistor is overloaded.
The brake is protected against short-circuiting of the brake resistor, and the
brake transistor is monitored to ensure that short-circuiting of the
transistor is detected. A relay/digital output can be used for protecting the
brake resistor against overloading in connection with a fault in the
adjustable frequency drive. In addition, the brake makes it possible to read
out the momentary power and the mean power for the last 120 seconds. The brake
can also monitor the power energizing and ensure that it does not exceed a
limit set in par. 2-12. In par. 2-13, select the function to carry out when
the power transmitted to the brake resistor exceeds the limit set in par.
2-12.
NOTE! Monitoring the braking energy is not a safety function; a thermal switch
is required for that purpose. The brake resistor circuit is not protected
against ground leakage.
Overvoltage control (OVC) (exclusive brake resistor) can be selected as an
alternative brake function in par. 2-17. This function is active for all
units. The function ensures that a trip can be avoided if the DC link voltage
increases. This is done by increasing the output frequency to limit the
voltage from the DC link. It is a very useful function if, for example, the
ramp-down time is too short because tripping the adjustable frequency drive is
avoided. In this situation, the ramp-down time is extended.
2.13 Mechanical brake control
2.13.1 Brake Resistor Cabling
EMC (twisted cables/shielding) To reduce the electrical noise from the wires
between the brake resistor and the adjustable frequency drive, the wires must
be twisted.
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2-37
2 Introduction to the VLT HVAC Drive
VLT® HVAC Drive Design Guide
For enhanced EMC performance, a metal shield can be used.
2.14 Extreme running conditions
Short Circuit (Motor Phase Phase)
2
The adjustable frequency drive is protected against short circuits by means of current measurement in each of the three motor phases or in the DC link.
A short circuit between two output phases will cause an overcurrent in the inverter. The inverter will be turned off individually when the short circuit
current exceeds the permitted value (Alarm 16 Trip Lock).
To protect the drive against a short circuit at the load sharing and brake outputs, please see the design guidelines.
Switching on the Output Switching on the output between the motor and the adjustable frequency drive is fully permitted. You cannot damage the adjustable frequency drive in any way by switching on the output. However, fault messages may appear.
Motor-generated Overvoltage The voltage in the intermediate circuit is increased when the motor acts as a generator. This occurs in the following cases:
1. The load drives the motor (at constant output frequency from the
adjustable frequency drive), i.e., the load generates energy.
2. During deceleration (“ramp-down”), if the moment of inertia is high the
friction is low and the ramp-down time is too short for the energy to be
dissipated as a loss in the adjustable frequency drive, the motor and the
installation.
3. Incorrect slip compensation setting may cause higher DC link voltage. The
control unit may attempt to correct the ramp if possible (par. 2-17
Overvoltage Control. The inverter turns off to protect the transistors and the
intermediate circuit capacitors when a certain voltage level is reached. See
par. 2-10 and par. 2-17 to select the method used for controlling the
intermediate circuit voltage level.
Line Drop-out During a line drop-out, the adjustable frequency drive keeps running until the intermediate circuit voltage drops below the minimum stop level, which is typically 15% below the adjustable frequency drive’s lowest rated supply voltage.
The line voltage before the drop-out and the motor load determine how long it takes for the inverter to coast.
Static Overload in VVCplus mode When the adjustable frequency drive is overloaded (the torque limit in par. 4-16/4-17 is reached), the control reduces the output frequency to reduce the load. If the overload is excessive, a current may occur that makes the adjustable frequency drive cut out after approximately 5-10 s.
Operation within the torque limit is limited in time (0-60 s) in par. 14-25.
2.14.1 Motor Thermal Protection
The motor temperature is calculated on the basis of motor current, output
frequency, and time or thermistor. See par. 1-90 in the Programming Guide.
2-38
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VLT® HVAC Drive Design Guide
2 Introduction to the VLT HVAC Drive
2
2.15 Safe Stop
2.15.1 Safe Stop
The adjustable frequency drive can perform the safety function Safe Torque Off
(As defined by draft CD IEC 61800-5-2) or Stop Category 0 (as defined in EN
60204-1). It is designed and deemed suitable for the requirements of Safety
Category 3 in EN 954-1. This function is called safe stop. Prior to
integrating and using safe stop in an installation, a thorough risk analysis
must be carried out on the installation in order to determine whether the safe
stop functionality and safety category are appropriate and sufficient. In
order to install and use the safe stop function in accordance with the
requirements of Safety Category 3 in EN 954-1, the related information and
instructions in the relevant Design Guide must be followed! The information
and instructions contained in the Instruction Manual are not sufficient for a
correct and safe use of the safe stop functionality!
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
2-39
2 Introduction to the VLT HVAC Drive
2
VLT® HVAC Drive Design Guide
Figure 2.3: Diagram showing all electrical terminals. (Terminal 37 present for
units with safe stop function only.)
2.15.2 Safe Stop Installation
To carry out an installation of a Category 0 Stop (EN60204) in conformity with
Safety Category 3 (EN954-1), follow these instructions: 1. The bridge (jumper)
between Terminal 37 and 24 V DC must be removed. Cutting or breaking the
jumper is not sufficient. Remove it entirely to avoid short-circuiting. See
jumper on illustration. 2. Connect terminal 37 to 24 V DC by a short circuit-
protected cable. The 24 V DC voltage supply must be interruptible by an
EN954-1 category 3 circuit interrupt device. If the interrupt device and the
adjustable frequency drive are placed in the same installation panel, you can
use an unshielded cable instead of a shielded one.
2-40
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VLT® HVAC Drive Design Guide
2 Introduction to the VLT HVAC Drive
2
Figure 2.4: Bridge jumper between terminal 37 and 24 VDC
The illustration below shows a Stopping Category 0 (EN 60204-1) with safety
Category 3 (EN 954-1). The circuit interruption is caused by an opening door
contact. The illustration also shows how to connect a non-safety-related
hardware coast.
Figure 2.5: Illustration of the essential aspects of an installation to achieve a Stopping Category 0 (EN 60204-1) with safety Category 3 (EN 954-1).
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
2-41
2 Introduction to the VLT HVAC Drive
2
VLT® HVAC Drive Design Guide
2-42
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
VLT® HVAC Drive Design Guide
3 VLT HVAC Selection
VLT HVAC Selection
3.1 Specifications
3.1.1 Line Supply 3 x 200-240 V AC
Normal overload 110% for 1 minute IP 20
A2
A2
A2
A3
A3
3
IP 21
A2
A2
A2
A3
A3
IP 55
A5
A5
A5
A5
A5
IP 66
A5
A5
A5
A5
A5
Line supply 200-240 V AC
Adjustable frequency drive
P1K1 P1K5 P2K2 P3K0 P3K7
Typical Shaft Output [kW]
1.1 1.5 2.2
3
3.7
Typical Shaft Output [HP] at 208 V
1.5 2.0 2.9 4.0 4.9
Output current
Continuous (3 x 200-240 V) [A]
6.6 7.5 10.6 12.5 16.7
Intermittent (3 x 200-240 V) [A]
7.3 8.3 11.7 13.8 18.4
Continuous kVA (208 V AC) [kVA]
2.38 2.70 3.82 4.50 6.00
Max. cable size:
(line, motor, brake) [mm2 /AWG] 2)
4/10
Max. input current
Continuous (3 x 200-240 V) [A]
5.9 6.8 9.5 11.3 15.0
Intermittent (3 x 200-240 V) [A]
6.5 7.5 10.5 12.4 16.5
Max. pre-fuses1) [A]
20
20
20
32
32
Environment
Estimated power loss at rated max. load [W] 4)
63
82 116 155 185
Weight enclosure IP 20 [kg]
4.9 4.9 4.9 6.6 6.6
Weight enclosure IP 21 [kg]
5.5 5.5 5.5 7.5 7.5
Weight enclosure IP 55 [kg] 13.5 13.5 13.5 13.5 13.5
Weight enclosure IP 66 [kg]
13.5 13.5 13.5 13.5 13.5
Efficiency 3)
0.96 0.96 0.96 0.96 0.96
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
3-1
3 VLT HVAC Selection
VLT® HVAC Drive Design Guide
Normal overload 110% for 1 minute
IP 21
B1
B1
B1
B2
IP 55
B1
B1
B1
B2
IP 66
B1
B1
B1
B2
Line supply 200-240 V AC
Adjustable frequency drive
P5K5 P7K5 P11K
P15K
Typical Shaft Output [kW]
5.5
7.5
11
15
Typical Shaft Output [HP] at 208 V
7.5
10
15
20
Output current
3
Continuous (3 x 200-240 V) [A]
24.2 30.8
46.2
59.4
Intermittent (3 x 200-240 V) [A]
26.6 33.9
50.8
65.3
Continuous kVA (208 V AC) [kVA]
8.7
11.1
16.6
21.4
Max. cable size:
(line, motor, brake) [mm2 /AWG] 2)
10/7
35/2
Max. input current
Continuous (3 x 200-240 V) [A]
22.0 28.0
42.0
54.0
Intermittent (3 x 200-240 V) [A]
24.2 30.8
46.2
59.4
Max. pre-fuses1) [A]
63
63
63
80
Environment
Estimated power loss at rated max. load [W] 4)
269
310
447
602
Weight enclosure IP 20 [kg]
Weight enclosure IP 21 [kg]
23
23
23
27
Weight enclosure IP 55 [kg]
23
23
23
27
Weight enclosure IP 66 [kg]
23
23
23
27
Efficiency 3)
0.96 0.96
0.96
0.96
3-2
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
VLT® HVAC Drive Design Guide
3 VLT HVAC Selection
Normal overload 110% for 1 minute IP 20 IP 21
C1
C1
C1
C2
C2
IP 55
C1
C1
C1
C2
C2
IP 66
C1
C1
C1
C2
C2
Line supply 200-240 V AC
Adjustable frequency drive
P18K P22K P30K P37K P45K
Typical Shaft Output [kW]
18.5 22
30
37
45
Typical Shaft Output [HP] at 208 V Output current
25
30
40
50
60
3
Continuous (3 x 200-240 V) [A]
74.8 88.0 115 143
170
Intermittent (3 x 200-240 V) [A]
82.3 96.8 127 157
187
Continuous kVA (208 V AC) [kVA]
26.9 31.7 41.4 51.5 61.2
Max. cable size:
(line, motor, brake) [mm2 /AWG] 2)
50/1/0
95/4/0 120/250 MCM
Max. input current
Continuous (3 x 200-240 V) [A]
68.0 80.0 104.0 130.0 154.0
Intermittent (3 x 200-240 V) [A]
74.8 88.0 114.0 143.0 169.0
Max. pre-fuses1) [A]
125 125 160 200
250
Environment
Estimated power loss at rated max. load [W] 4)
737 845 1140 1353 1636
Weight enclosure IP 20 [kg]
Weight enclosure IP 21 [kg]
45
45
65
65
65
Weight enclosure IP 55 [kg]
45
45
65
65
65
Weight enclosure IP 66 [kg]
45
45
65
65
65
Efficiency 3)
0.96 0.97 0.97 0.97 0.97
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
3-3
3 VLT HVAC Selection
3.1.2 Line Supply 3 x 380-480 V AC
Normal overload 110% for 1 minute
Adjustable frequency drive
Typical Shaft Output [kW]
Typical Shaft Output [HP] at 460 V
IP 20
IP 21
IP 55
3
IP 66
Output current
Continuous
(3 x 380-440 V) [A]
Intermittent
(3 x 380-440 V) [A]
Continuous
(3 x 440-480 V) [A]
Intermittent
(3 x 440-480 V) [A]
Continuous kVA
(400 V AC) [kVA]
Continuous kVA
(460 V AC) [kVA]
Max. cable size:
(line, motor, brake)
[[mm2/
AWG] 2)
Max. input current
Continuous
(3 x 380-440 V) [A]
Intermittent
(3 x 380-440 V) [A]
Continuous
(3 x 440-480 V) [A]
Intermittent
(3 x 440-480 V) [A]
Max. pre-fuses1)[A]
Environment
Estimated power loss
at rated max. load [W] 4)
Weight enclosure IP 20 [kg]
Weight enclosure IP 21 [kg]
Weight enclosure IP 55 [kg]
Weight enclosure IP 66 [kg]
Efficiency 3)
VLT® HVAC Drive Design Guide
P1K1 1.1 1.5 A2
A5 A5
P1K5 1.5 2.0 A2
A5 A5
P2K2 2.2 2.9 A2
A5 A5
P3K0 3 4.0 A2
A5 A5
P4K0 4 5.3 A2
A5 A5
P5K5 5.5 7.5 A3
A5 A5
P7K5 7.5 10 A3
A5 A5
3
4.1
5.6
7.2
10
13
16
3.3
4.5
6.2
7.9
11
14.3 17.6
2.7
3.4
4.8
6.3
8.2
11
14.5
3.0
3.7
5.3
6.9
9.0 12.1 15.4
2.1
2.8
3.9
5.0
6.9
9.0 11.0
2.4
2.7
3.8
5.0
6.5
8.8 11.6
4/ 10
2.7
3.7
5.0
6.5
9.0
11.7 14.4
3.0
4.1
5.5
7.2
9.9
12.9 15.8
2.7
3.1
4.3
5.7
7.4
9.9
13.0
3.0
3.4
4.7
6.3
8.1
10.9 14.3
10
10
20
20
20
32
32
58
62
88
116
124
187 255
4.8
4.9
4.9
4.9
4.9
6.6
6.6
13.5 13.5 13.5 13.5 13.5 14.2 14.2 13.5 13.5 13.5 13.5 13.5 14.2 14.2 0.96 0.97 0.97 0.97 0.97 0.97 0.97
3-4
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
VLT® HVAC Drive Design Guide
3 VLT HVAC Selection
Normal overload 110% for 1 minute Adjustable frequency drive Typical Shaft Output [kW] Typical Shaft Output [HP] at 460 V IP 20 IP 21
P11K 11 15
P15K 15 20
P18K 18.5 25
P22K 22 30
P30K 30 40
P37K 37 50
P45K 45 60
P55K 55 75
P75K 75 100
P90K 90 125
B1 B1 B1 B2 B2
C1 C1 C1 C2
C2
IP 55 IP 66 Output current
Continuous (3 x 380-440 V) [A] Intermittent (3 x 380-440 V) [A] Continuous (3
x 440-480 V) [A] Intermittent (3 x 440-480 V) [A] Continuous kVA (400 V AC)
[kVA] Continuous kVA (460 V AC) [kVA] Max. cable size: (line, motor, brake)
[[mm2/ AWG] 2) Max. input current
B1 B1 B1 B2 B2 C1 C1 C1 C2
–
B1 B1 B1 B2 B2 C1 C1 C1 C2
–
3
24 32 37.5 44 61 73 90 106 147 177
26.4 35.2 41.3 48.4 67.1 80.3 99 117 162 195
21 27 34 40 52 65 80 105 130 160
23.1 29.7 37.4 44 61.6 71.5 88 116 143 176
16.6 22.2 26 30.5 42.3 50.6 62.4 73.4 102 123
16.7 21.5 27.1 31.9 41.4 51.8 63.7 83.7 104 128
10/7
35/2
50/1/0
104 128
Continuous (3 x 380-440 V) [A]
22 29 34 40 55 66 82 96 133 161
Intermittent (3 x 380-440 V) [A]
24.2 31.9 37.4 44 60.5 72.6 90.2 106 146 177
Continuous (3 x 440-480 V) [A]
19 25 31 36 47 59 73 95 118 145
Intermittent (3 x 440-480 V) [A]
20.9 27.5 34.1 39.6 51.7 64.9 80.3 105 130 160
Max. pre-fuses1)[A]
63 63 63 63 80 100 125 160 250 250
Environment
Estimated power loss at rated max. load [W] 4)
278 392 465 525 739 698 843 1083 1384 1474
Weight enclosure IP 20 [kg]
Weight enclosure IP 21 [kg] 23 23 23 27 27 45 45 45 65
65
Weight enclosure IP 55 [kg] 23 23 23 27 27 45 45 45 65
65
Weight enclosure IP 66 [kg] 23 23 23 27 27 45 45 45
–
–
Efficiency 3)
0.98 0.98 0.98 0.98 0.98 0.98 0.98 0.98 0.98 0.99
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
3-5
3 VLT HVAC Selection
3
Normal overload 110% for 1 minute
3-6
Adjustable frequency drive
P110
P132
P160
P200
P250
P315
P355
P400
P450
Typical Shaft Output [kW]
110
132
160
200
250
315
355
400
450
Typical Shaft Output [HP] at 460V
150
200
250
300
350
450
500
550
600
IP 00
D3
D3
D4
D4
D4
E2
E2
E2
E2
IP 21
D1
D1
D2
D2
D2
E1
E1
E1
E1
IP 54
D1
D1
D2
D2
D2
E1
E1
E1
E1
Output current
Continuous (3 x 400 V) [A]
212
260
315
395
480
600
658
745
800
Intermittent (3 x 400 V) [A]
233
286
347
435
528
660
724
820
880
Continuous (3 x 460-500 V) [A]
190
240
302
361
443
540
590
678
730
Intermittent (3 x 460-500 V) [A]
209
264
332
397
487
594
649
746
803
Continuous kVA (400 V AC) [kVA]
147
180
218
274
333
416
456
516
554
Continuous kVA (460 V AC) [kVA]
151
191
241
288
353
430
470
540
582
Max. cable size:
(line power, motor, brake) [mm2/ AWG] 2)
2×70 2×2/0
2×185 2×350 mcm
4×240 4×500 mcm
Max. input current
Continuous (3 x 400 V) [A]
204
251
304
381
463
590
647
733
787
Continuous (3 x 460/500V) [A]
183
231
291
348
427
531
580
667
718
Max. pre-fuses1)[A]
300
350
400
500
600
700
900
900
900
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
Environment
Estimated power loss at rated max. load [W] 4)
3234
3782
4213
5119
5893
7630
7701
8879
9428
Weight enclosure IP 00 [kg]
81.9
90.5
111.8
122.9
137.7
221.4
234.1
236.4
277.3
Weight enclosure IP 21 [kg]
95.5
104.1
125.4
136.3
151.3
263.2
270.0
272.3
313.2
Weight enclosure IP 54 [kg]
95.5
104.1
125.4
136.3
151.3
263.2
270.0
272.3
313.2
Efficiency 3)
0.98
0.98
0.98
0.98
0.98
0.98
0.98
0.98
0.98
-
For type of fuse, see section Fuses.
-
American Wire Gauge
-
Measured using 16.4 ft. [5 m] shielded motor cables at rated load and rated frequency.
-
The typical power loss is at normal load conditions and expected to be within +/- 15% (tolerance relates to variety in voltage and cable conditions).
Values are based on a typical motor efficiency (eff2/eff3 border line). Lower efficiency motors will also add to the power loss in the adjustable frequency drive and vice versa.
If the switching frequency is raised from nominal, the power losses may rise significantly.
LCP and typical control card power consumption values are included. Further options and customer load may add up to 30 W to the losses. (though typically only 4W extra for a fully loaded control card, or options
for slot A or slot B, each).
Although measurements are made with state of the art equipment, some measurement inaccuracy must be allowed for (+/- 5%).
VLT® HVAC Drive Design Guide
VLT® HVAC Drive Design Guide
3 VLT HVAC Selection
3.1.3 Line Supply 3 x 525-600 V AC
Normal overload 110% for 1 minute
Size:
P1K1 P1K5 P2K2 P3K0 P3K7 P4K0 P5K5 P7K5
Typical Shaft Output [kW]
1.1
1.5
2.2
3
3.7
4
5.5
7.5
Output current
Continuous (3 x 525-550 V) [A] Intermittent (3 x 525-550 V) [A]
2.6
2.9
4.1
5.2
–
6.4
9.5
11.5
3
2.9
3.2
4.5
5.7
–
7.0
10.5 12.7
Continuous (3 x 525-600 V) [A]
2.4
2.7
3.9
4.9
–
6.1
9.0
11.0
Intermittent (3 x 525-600 V) [A]
2.6
3.0
4.3
5.4
–
6.7
9.9
12.1
Continuous kVA (525 V AC) [kVA]
2.5
2.8
3.9
5.0
–
6.1
9.0
11.0
Continuous kVA (575 V AC) [kVA]
2.4
2.7
3.9
4.9
–
6.1
9.0
11.0
Max. cable size
24 – 10 AWG
(line, motor, brake)
– 0.00031-0.0062 in. [0.2-4
[AWG] 2) [mm2]
mm]2
Max. input current
Continuous (3 x 525-600 V) [A]
2.4
2.7
4.1
5.2
–
5.8
8.6
10.4
Intermittent (3 x 525-600 V) [A]
2.7
3.0
4.5
5.7
–
6.4
9.5
11.5
Max. pre-fuses1) [A]
10
10
20
20
–
20
32
32
Environment
Estimated power loss at rated max. load [W] 4)
50
65
92
122
–
145
195
261
Enclosure IP 20
Weight, enclosure IP 20 [kg]
6.5
6.5
6.5
6.5
–
6.5
6.6
6.6
Efficiency 4)
0.97 0.97 0.97 0.97 – 0.97 0.97 0.97
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
3-7
3 VLT HVAC Selection
3
Normal overload 110% for 1 minute
3-8
Adjustable frequency drive
P110
P132
P160
P200
P250
P315
P355
P400
P500
P560
Typical Shaft Output [kW]
110
132
160
200
250
315
355
400
500
560
Typical Shaft Output [HP] at 575 V
150
200
250
300
350
400
450
500
600
650
IP 00
D3
D3
D4
D4
D4
D4
E2
E2
E2
E2
IP 21
D1
D1
D2
D2
D2
D2
E1
E1
E1
E1
IP 54
D1
D1
D2
D2
D2
D2
E1
E1
E1
E1
Output current
Continuous (3 x 550 V) [A]
162
201
253
303
360
418
470
523
596
630
Intermittent (3 x 550 V) [A]
178
221
278
333
396
460
517
575
656
693
Continuous (3 x 575-690V) [A]
155
192
242
290
344
400
450
500
570
630
Intermittent (3 x 575-690 V) [A]
171
211
266
319
378
440
495
550
627
693
Continuous kVA (550 V AC) [kVA]
154
191
241
289
343
398
448
498
568
600
Continuous kVA (575 V AC) [kVA]
154
191
241
289
343
398
448
498
568
627
Continuous kVA (690 V AC) [kVA]
185
229
289
347
411
478
538
598
681
753
Max. cable size:
(line power, motor, brake) [mm2/ AWG] 2)
2×70 2×2/0
2×185 2×350 mcm
4×240 4×500 mcm
Max. input current
Continuous (3 x 550 V) [A]
158
198
245
299
355
408
453
504
574
607
Continuous (3 x 575 V) [A]
151
189
234
286
339
390
434
482
549
607
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
Continuous (3 x 690 V) [A]
155
197
240
296
352
400
434
482
549
607
Max. pre-fuses1)[A]
225
250
350
400
500
600
700
700
900
900
Environment
Estimated power loss at rated max. load [W] 4)
3114
3612
4293
5156
5821
6149
6449
7249
8727
9673
Weight enclosure IP 00 [kg]
81.9
90.5
111.8
122.9
137.7
151.3
221
221
236
277
Weight enclosure IP 21 [kg]
95.5
104.1
125.4
136.3
151.3
164.9
263
263
272
313
Weight enclosure IP 54 [kg]
95.5
104.1
125.4
136.3
151.3
164.9
263
263
272
313
Efficiency 3)
0.98
0.98
0.98
0.98
0.98
0.98
0.98
0.98
0.98
0.98
-
For type of fuse, see section Fuses.
-
American Wire Gauge
-
Measured using 16.4 ft. [5 m] shielded motor cables at rated load and rated frequency.
-
The typical power loss is at normal load conditions and expected to be within +/- 15% (tolerance relates to variety in voltage and cable conditions).
Values are based on a typical motor efficiency (eff2/eff3 border line). Lower efficiency motors will also add to the power loss in the adjustable frequency drive and vice versa.
If the switching frequency is raised from nominal, the power losses may rise significantly.
LCP and typical control card power consumption values are included. Further options and customer load may add up to 30 W to the losses. (though typically only 4W extra for a fully loaded control card, or options
for slot A or slot B, each).
Although measurements are made with state of the art equipment, some measurement inaccuracy must be allowed for (+/- 5%).
VLT® HVAC Drive Design Guide
VLT® HVAC Drive Design Guide
3 VLT HVAC Selection
Line power supply (L1, L2, L3): Supply voltage Supply voltage Supply frequency Max. imbalance temporary between line phases True Power Factor () Displacement Power Factor (cos) near unity Switching on input supply L1, L2, L3 (power-ups) enclosure type A Switching on input supply L1, L2, L3 (power-ups) enclosure type B, C Switching on input supply L1, L2, L3 (power-ups) enclosure type D, E Environment according to EN60664-1
380-480 V ±10%
525-600 V ±10%
50/60 Hz
3.0% of rated supply voltage
0.9 nominal at rated load
(> 0.98)
maximum twice/min.
maximum once/min.
3
maximum once/2 min.
overvoltage category III / pollution degree 2
The unit is suitable for use on a circuit capable of delivering not more than 100.000 RMS symmetrical Amperes, 480/600 V maximum.
Motor output (U, V, W): Output voltage Output frequency Switching on output Ramp times Torque characteristics: Starting torque (Constant torque) Starting torque Overload torque (Constant torque)
0 – 100% of supply voltage 0 – 1000 Hz Unlimited
1 – 3600 sec.
maximum 110% for 1 min. maximum 120% up to 0.5 sec.
maximum 110% for 1 min.*
*Percentage relates to the nominal torque for the VLT HVAC Drive.
Cable lengths and cross-sections: Max. motor cable length, shielded/armored Max. motor cable length, unshielded/unarmored Max. cross-section to motor, line power, load sharing and brake * Maximum cross-section to control terminals, rigid wire Maximum cross-section to control terminals, flexible cable Maximum cross-section to control terminals, cable with enclosed core Minimum cross-section to control terminals
VLT HVAC Drive: 492 ft [150 m] VLT HVAC Drive: 984 ft [300 m] 0.0023 in.2 [1.5
mm2]/16 AWG (2 x 0.0012 in.2 [2 x 0.75 mm2]) 0.0016 in.2 [1 mm2]/18 AWG
0.00078 in.2 [0.5 mm2]/20 AWG 0.00039 in.2 [0.25 mm2]
- See Line Supply tables for more information!
Digital inputs: Programmable digital inputs Terminal number Logic Voltage level Voltage level, logic’0′ PNP Voltage level, logic’1′ PNP Voltage level, logic ‘0’ NPN Voltage level, logic ‘1’ NPN Maximum voltage on input Input resistance, Ri
4 (6) 18, 19, 27 1), 29, 32, 33,
PNP or NPN 0 – 24 V DC
< 5 V DC > 10 V DC > 19 V DC < 14 V DC
28 V DC approx. 4 k
All digital inputs are galvanically isolated from the supply voltage (PELV) and other high-voltage terminals. 1) Terminals 27 and 29 can also be programmed as output.
Analog inputs: Number of analog inputs Terminal number Modes Mode select Voltage mode
2 53, 54 Voltage or current Switch S201 and switch S202 Switch S201/switch S202 = OFF (U)
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
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3 VLT HVAC Selection
VLT® HVAC Drive Design Guide
Voltage level
Input resistance, Ri
Max. voltage
Current mode
Current level
Input resistance, Ri
Max. current
Resolution for analog inputs
3
Accuracy of analog inputs
Bandwidth
The analog inputs are galvanically isolated from the supply voltage (PELV) and other high-voltage terminals.
: 0 to + 10 V (scaleable) approx. 10 k ± 20 V
Switch S201/switch S202 = ON (I) 0/4 to 20 mA (scalable) approx. 200 30 mA 10
bit (+ sign)
Max. error 0.5% of full scale : 200 Hz
Pulse inputs: Programmable pulse inputs Terminal number pulse Max. frequency at terminal, 29, 33 Max. frequency at terminal, 29, 33 Min. frequency at terminal 29, 33 Voltage level Maximum voltage on input Input resistance, Ri Pulse input accuracy (0.1-1 kHz) Analog output: Number of programmable analog outputs Terminal number Current range at analog output Max. load to common at analog output Accuracy on analog output Resolution on analog output
2 29, 33 110 kHz (push-pull driven) 5 kHz (open collector)
4 Hz see section on Digital input
28 V DC approx. 4 k Max. error: 0.1% of full scale
1 42 0/4 – 20 mA 500 Max. error: 0.8% of full scale 8 bit
The analog output is galvanically isolated from the supply voltage (PELV) and other high-voltage terminals.
Control card, RS-485 serial communication: Terminal number Terminal number 61
68 (P,TX+, RX+), 69 (N,TX-, RX-) Common for terminals 68 and 69
The RS-485 serial communication circuit is functionally separated from other central circuits and galvanically isolated from the supply voltage (PELV).
Digital output: Programmable digital/pulse outputs Terminal number Voltage level at digital/frequency output Max. output current (sink or source) Max. load at frequency output Max. capacitive load at frequency output
2 27, 29 1) 0 – 24 V
40 mA 1 k 10 nF
3-10
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VLT® HVAC Drive Design Guide
3 VLT HVAC Selection
Minimum output frequency at frequency output Maximum output frequency at frequency output Accuracy of frequency output Resolution of output frequency
0 Hz 32 kHz Max. error: 0.1% of full scale 12 bit
- Terminal 27 and 29 can also be programmed as input.
The digital output is galvanically isolated from the supply voltage (PELV) and other high-voltage terminals.
Control card, 24 V DC output: Terminal number Max. load
12, 13 : 200 mA
3
The 24 V DC supply is galvanically isolated from the supply voltage (PELV), but has the same potential as the analog and digital inputs and outputs.
Relay outputs: Programmable relay outputs Relay 01 Terminal number Max. terminal load (AC-1)1) on 1-3 (NC), 1-2 (NO) (Resistive load) Max. terminal load (AC-15)1) (Inductive load @ cos 0.4) Max. terminal load (DC-1)1) on 1-2 (NO), 1-3 (NC) (Resistive load) Max. terminal load (DC-13)1) (Inductive load) Relay 02 Terminal number Max. terminal load (AC-1)1) on 4-5 (NO) (Resistive load) Max. terminal load (AC-15)1) on 4-5 (NO) (Inductive load @ cos 0.4) Max. terminal load (DC-1)1) on 4-5 (NO) (Resistive load) Max. terminal load (DC-13)1) on 4-5 (NO) (Inductive load) Max. terminal load (AC-1)1) on 4-6 (NC) (Resistive load) Max. terminal load (AC-15)1) on 4-6 (NC) (Inductive load @ cos 0.4) Max. terminal load (DC-1)1) on 4-6 (NC) (Resistive load) Max. terminal load (DC-13)1) on 4-6 (NC) (Inductive load) Min. terminal load on 1-3 (NC), 1-2 (NO), 4-6 (NC), 4-5 (NO) Environment according to EN 60664-1
2 1-3 (break), 1-2 (make)
240 V AC, 2 A 240 V AC, 0.2 A
60 V DC, 1 A 24 V DC, 0.1 A 4-6 (break), 4-5 (make) 240 V AC, 2 A 240 V AC,
0.2 A
80 V DC, 2 A 24 V DC, 0.1 A 240 V AC, 2 A 240 V AC, 0.2 A
50 V DC, 2 A 24 V DC, 0.1 A 24 V DC 10 mA, 24 V AC 20 mA overvoltage category
III/pollution degree 2
- IEC 60947 part 4 and 5 The relay contacts are galvanically isolated from the rest of the circuit by reinforced isolation (PELV).
Control card, 10 V DC output: Terminal number Output voltage Max. load
50 10.5 V ±0.5 V
25 mA
The 10 V DC supply is galvanically isolated from the supply voltage (PELV) and other high-voltage terminals.
Control characteristics: Resolution of output frequency at 0 – 1000 Hz System response time (terminals 18, 19, 27, 29, 32, 33) Speed control range (open- loop) Speed accuracy (open-loop)
: +/- 0.003 Hz : 2 ms
1:100 of synchronous speed 30 – 4000 rpm: Maximum error of ±8 rpm
All control characteristics are based on a 4-pole asynchronous motor
Surroundings: Enclosure enclosure type D Enclosure enclosure type D, E Enclosure kit available enclosure type D Vibration test Max. relative humidity Aggressive environment (IEC 721-3-3), uncoated Aggressive environment (IEC 721-3-3), coated Test method according to IEC 60068-2-43 H2S (10 days)
IP 00, IP 21, IP 54 IP 21, IP 54
IP 21/TYPE 1/IP 4X top 1.0 g
5%-95% (IEC 721-3-3; Class 3K3 (non-condensing) during operation class 3C2
class 3C3
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
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3 VLT HVAC Selection
VLT® HVAC Drive Design Guide
Ambient temperature (at 60 AVM switching mode) – with derating
max. 55 ° C1)
– with full output power, typical EFF2 motors – at full continuous FC output current
max. 50 ° C1) max. 45 ° C1)
- For more information on derating for high ambient temperature AVM and SFAVM, see the Design Guide, section on Special Conditions.
Minimum ambient temperature during full-scale operation
3
Minimum ambient temperature at reduced performance Temperature during storage/transport
Maximum altitude above sea level without derating
Maximum altitude above sea level with derating
32°F [0°C] 14°F [-10°C] -13°-+°149/°158°F [-25°-+65°/70°C] 3280 ft [1000 m] 9842 ft [3000 m]
Derating for high altitude, see section on special conditions.
EMC standards, Emission EMC standards, Immunity
EN 61800-3, EN 61000-6-3/4, EN 55011, IEC 61800-3 EN 61800-3, EN 61000-6-1/2,
EN 61000-4-2, EN 61000-4-3, EN 61000-4-4, EN 61000-4-5, EN 61000-4-6
See section on special conditions!
Control card performance: Scan interval Control card, USB serial communication: USB standard USB plug
: 5 ms
1.1 (Full speed) USB type B “device” plug
Connection to PC is carried out via a standard host/ device USB cable. The USB connection is galvanically isolated from the supply voltage (PELV) and other high-voltage terminals. The USB connection is not galvanically isolated from protection ground. Use only isolated laptop/PC as connection to the USB connector on VLT HVAC Drive or an isolated USB cable/drive.
Protection and Features: · Electronic thermal motor protection against overload. · Temperature monitoring of the heatsink ensures that the adjustable frequency drive trips if the temperature reaches 203°F ± 9°F [95°C ± 5°C]. An overload temperature cannot be reset until the temperature of the heatsink is below 158°F ± 9°F [70°C ± 5°C] (Guideline – these temperatures may vary for different power sizes, enclosures, etc.). VLT HVAC drive has an auto-derating function to prevent it’s heatsink from reaching 203°F [95°C]. · The adjustable frequency drive is protected against short-circuits on motor terminals U, V, W. · If a line phase is missing, the adjustable frequency drive trips or issues a warning (depending on the load). · Monitoring of the intermediate circuit voltage ensures that the adjustable frequency drive trips if the intermediate circuit voltage is too low or too high. · The adjustable frequency drive is protected against ground faults on motor terminals U, V, W.
3.2 Efficiency
Efficiency of VLT HVAC ( VLT)
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VLT® HVAC Drive Design Guide
3 VLT HVAC Selection
The load on the adjustable frequency drive has little effect on its
efficiency. In general, the efficiency is the same at the rated motor
frequency fM,N, even if the motor supplies 100% of the rated shaft torque, or
only 75% in case of part loads.
This also means that the efficiency of the adjustable frequency drive does not
change even if other U/f characteristics are chosen. However, the U/f
characteristics influence the efficiency of the motor.
The efficiency declines a little when the switching frequency is set to a
value greater than 5 kHz. The efficiency will also be slightly reduced if the
line voltage is 480 V, or if the motor cable is longer than 98.43 ft. [30 m].
3
Efficiency of the motor (MOTOR ) The efficiency of a motor connected to the
adjustable frequency drive depends on magnetizing level. In general, the
efficiency is just as good as with line operation. The efficiency of the motor
depends on the type of motor.
In the range of 75-100% of the rated torque, the efficiency of the motor is
practically constant, both when it is controlled by the adjustable frequency
drive, and when it runs directly on line power.
In small motors, the influence from the U/f characteristic on efficiency is
marginal. However, in motors from 15 hp [11 kW] and up, the advantages are
significant.
In general, the switching frequency does not affect the efficiency of small
motors. The efficiency of motors from 15 hp [11 kW] and up improves by 1-2%.
This is because the sine shape of the motor current is almost perfect at high
switching frequency.
Efficiency of the system (SYSTEM ) To calculate the system efficiency, the
efficiency of VLT HVAC (VLT) is multiplied by the efficiency of the motor
(MOTOR): SYSTEM) = VLT x MOTOR
Calculate the efficiency of the system at different loads based on the graph
below.
3.3 Acoustic noise
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
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3 VLT HVAC Selection
VLT® HVAC Drive Design Guide
The acoustic noise from the adjustable frequency drive comes from three
sources: 1. DC intermediate circuit coils. 2. Integrated fan. 3. RFI filter
choke.
Typical values are measured at a distance of 3.28 ft. [1 m] from the unit:
3 A2
Encapsulation
At reduced fan speed (50%) [dBA] *** 51
A3
51
A5
54
B1
61
B2
58
C1
52
C2
55
D1+D3
74
D2+D4
73
E1/E2 *
73
E1/E2 **
82
- 450 hp [315 kW], 380-480 VAC and 500 hp [355 kW], 525-600 VAC only!
** Remaining E1+E2 power sizes.
*** For D and E sizes, reduced fan speed is at 87%, measured at 200 V.
Full fan speed [dBA] 60 60 63 67 70 62 65 76 74 74 83
3.4 Peak voltage on motor
When a transistor in the inverter bridge switches, the voltage across the
motor increases by a du/dt ratio depending on: – the motor cable (type, cross-
section, length, shielded or unshielded) – inductance
The natural induction causes an overshoot UPEAK in the motor voltage before it
stabilizes itself at a level depending on the voltage in the intermediate
circuit. The rise time and the peak voltage UPEAK affect the service life of
the motor. If the peak voltage is too high, motors without phase coil
insulation are especially affected. If the motor cable is short (by a few
yards), the rise time and peak voltage are lower. If the motor cable is long
(328 ft. [100 m]), the rise time and peak voltage are higher.
In motors without phase insulation paper or other insulation reinforcement
suitable for operation with voltage supply (such as an adjustable frequency
drive), fit a du/dt filter or a sine-wave filter on the output of the
adjustable frequency drive.
3.5 Special Conditions
3.5.1 Purpose of derating
Derating must be taken into account when using the adjustable frequency drive
at low air pressure (high elevations), at low speeds, with long motor cables,
cables with a large cross-section or at high ambient temperature. The required
action is described in this section.
3.5.2 Derating for Ambient Temperature
The average temperature (TAMB, AVG) measured over 24 hours must be at least
9°F [5°C] lower than the maximum allowed ambient temperature (TAMB,MAX).
If the adjustable frequency drive is operated at high ambient temperatures,
the continuous output current should be decreased.
3-14
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VLT® HVAC Drive Design Guide
3 VLT HVAC Selection
The derating depends on the switching pattern, which can be set to 60 AVM or SFAVM in parameter 14-00.
A enclosures 60 AVM – Pulse Width Modulation
SFAVM – Stator Frequency Asyncron Vector Modulation
3
Figure 3.1: Derating of Iout for different TAMB, MAX for enclosure A, using 60 AVM
Figure 3.2: Derating of Iout for different TAMB, MAX for enclosure A, using SFAVM
In enclosure A, the length of the motor cable has a relatively high impact on the recommended derating. Therefore, the recommended derating for an application with max. 32 ft. [10 m] motor cable is also shown.
Figure 3.3: Derating of Iout for different TAMB, MAX for enclosure A, using 60 AVM and maximum 32 ft [10 m] motor cable
Figure 3.4: Derating of Iout for different TAMB, MAX for enclosure A, using SFAVM and a maximum of 32 ft. [10 m] motor cable
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
3-15
3 VLT HVAC Selection
B enclosures 60 AVM – Pulse Width Modulation
VLT® HVAC Drive Design Guide
SFAVM – Stator Frequency Asyncron Vector Modulation
3
Figure 3.5: Derating of Iout for different TAMB, MAX for enclosure B, using 60
AVM in normal torque mode (110% over torque)
C enclosures 60 AVM – Pulse Width Modulation
Figure 3.6: Derating of Iout for different TAMB, MAX for enclosure B, using
SFAVM in normal torque mode (110% over torque)
SFAVM – Stator Frequency Asyncron Vector Modulation
Figure 3.7: Derating of Iout for different TAMB, MAX for enclosure C, using 60
AVM in normal torque mode (110% over torque)
D enclosures 60 AVM – Pulse Width Modulation, 380-480 V
Figure 3.8: Derating of Iout for different TAMB, MAX for enclosure C, using
SFAVM in normal torque mode (110% over torque)
SFAVM – Stator Frequency Asyncron Vector Modulation
Figure 3.9: Derating of Iout for different TAMB, MAX for enclosure D at 480 V, using 60 AVM in normal torque mode (110% over torque)
Figure 3.10: Derating of Iout for different TAMB, MAX for enclosure D at 480 V, using SFAVM in normal torque mode (110% over torque)
3-16
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VLT® HVAC Drive Design Guide
60 AVM – Pulse Width Modulation, 525-600 V (except P315)
3 VLT HVAC Selection
SFAVM – Stator Frequency Asyncron Vector Modulation
Figure 3.11: Derating of Iout for different TAMB, MAX for enclosure D at 600
V, using 60 AVM in normal torque mode (110% over torque). Note: not valid for
P315.
60 AVM – Pulse Width Modulation, 525-600 V, P315
3
Figure 3.12: Derating of Iout for different TAMB, MAX for enclosure D at 600
V, using SFAVM in normal torque mode (110% over torque). Note: not valid for
P315.
SFAVM – Stator Frequency Asyncron Vector Modulation
Figure 3.13: Derating of Iout for different TAMB, MAX for enclosure D at 600
V, using 60 AVM in normal torque mode (110% over torque). Note: P315 only.
E enclosures 60 AVM – Pulse Width Modulation, 380-480 V
Figure 3.14: Derating of Iout for different TAMB, MAX for enclosure D at 600
V, using SFAVM in normal torque mode (110% over torque). Note: P315 only.
SFAVM – Stator Frequency Asyncron Vector Modulation
Figure 3.15: Derating of Iout for different TAMB, MAX for enclosure E at 480 V, using 60 AVM in normal torque mode (110% over torque)
Figure 3.16: Derating of Iout for different TAMB, MAX for enclosure E at 480 V, using SFAVM in normal torque mode (110% over torque)
MG.11.B5.22 – VLT® is a registered Danfoss trademark.
3-17
3 VLT HVAC Selection
60 AVM – Pulse Width Modulation, 525-600 V
VLT® HVAC Drive Design Guide
SFAVM – Stator Frequency Asyncron Vector Modulation
3
Figure 3.17: Derating of Iout for different TAMB, MAX for enclosure E at 600
V, using 60 AVM in normal torque mode (110% over torque).
Figure 3.18: Derating of Iout for different TAMB, MAX for enclosure E at 600 V, using SFAVM in normal torque mode (110% over torque).
3.5.3 Derating for Low Air Pressure
The cooling capability of air is decreased at a lower air pressure.
At altitudes higher than 6,600 feet [2 km], please contact Danfoss Drives
regarding PELV.
At an altitude lower than 3,280 ft [1,000 m], no derating is necessary; but at
an altitude higher than 3,280 ft [1,000 m], the ambient temperature (TAMB) or
max. output current (Iout) should be derated in accordance with the diagram
shown.
Figure 3.19: Derating of output current versus altitude at TAMB, MAX. At
altitudes higher than 6,600 feet [2 km], please contact Danfoss Drives
regarding PELV.
An alternative is to lower the ambient temperature at high altitudes and
thereby ensure 100% output current at high altitudes.
3.5.4 Derating for Running at Low Speed
When a motor is connected to an adjustable frequency drive, it is necessary to
make sure that the cooling of the motor is adequate. A problem may occur at
low RPM values in constant torque applications. The motor fan may not be able
to supply the required volume of air for cooling, which limits the torque that
can be supported. Therefore, if the motor is to be run continuously at an RPM
value lower than half of the rated value, the motor must be supplied with
additional air-cooling (or a motor designed for this type of operation may be
used).
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VLT® HVAC Drive Design Guide
3 VLT HVAC Selection
An alternative is to reduce the load level of the motor by choosing a larger motor. However, the design of the adjustable frequency drive limits the motor size.
3.5.5 Derating for Installing Long Motor Cables or Cables with Larger Cross- Section
The maximum cable length for this adjustable frequency drive is 984 ft [300 m] for unshielded cable, and 492 ft [150 m] for shielded cable.
The adjustable frequency drive has been designed to work using a motor cable with a rated cross-section. If a cable with a larger cross-section is used,
3
reduce the output current by 5% for every step the cross-section is increased.
(Increased cable cross-section leads to increased capacity to ground, and thus an increased ground leakage current).
3.5.6 Automatic adaptations to ensure performance
The adjustable frequency drive constantly checks for critical levels of
internal temperature, load current, high voltage on the intermediate circuit
and low motor speeds. As a response to a critical level, the adjustable
frequency drive can adjust the switching frequency and/or change the switching
pattern in order to ensure the performance of the drive. The capability to
automatically reduce the output current extends the acceptable operating
conditions even further.
3.6 Options and Accessories
Danfoss offers a wide range of options and accessories for the VLT adjustable
frequency drives.
3.6.1 Mounting Option Modu
References
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