bkvibro AS-668 Measuring Machine Vibration Acceleration Sensor Instructions
- June 4, 2024
- bkvibro
Table of Contents
bkvibro AS-668 Measuring Machine Vibration Acceleration Sensor
Hint
NOTE!
This manual is a part of the product. Read the manual carefully before using
the product and keep it accessible for future use.
Pictograms and their Meanings
This symbol warns of dangerous situations which can result from misuse of the product.
User Qualification
Ensure that all work in conjunction with our systems is performed by skilled,
expert and authorized workers (for ATEX systems according to EN 60079-14).
Among these works are:
Installation and Commissioning
Installation and commissioning primarily concern work on electrical equipment.
These works may be performed exclusively by electricians or workers instructed
and supervised by an electrician in accordance with electrotechnical
regulations/directives.
Change of System Specification
Any change of system specification has its effects on monitoring process with
stationary systems and on the measuring sequence with portable measuring
systems.
Intended Use
If sensors and cables are used in a way not described in the relevant user
manuals, function and protection may be impaired and serious personal damage,
death or serious, irreversible injuries may result.
- Exclusively use sensor as specified in data sheet. Any use other than specified is considered inappropriate. Brüel & Kjær Vibro does not assume any liability for damages resulting from inappropriate use. The user is solely responsible.
- Mounted sensors must not be used as steps.
- Ensure that system is exposed only to admissible environmental influences specified in technical system data sheet.
- Maintain electrical equipment in regular intervals. Remedy defects, e.g. loose wires, defective connectors, immediately.
Hot surfaces
- In line with the user manuals, sensors and cables can be operated in extensive ambient temperature ranges, whereby they can become hot through self-heating on housing walls and can produce burning.
- When mounted at external heat or cold sources (e.g. machine parts), systems, sensors and cables can adopt dangerous temperatures, whereby burning, among other things, can occur in the event of contact.
Recommendations to User
If the use of the system in conjunction with machines or plant sections can
produce risks outside of Brüel & Kjær Vibro’s responsibility, the user is
expected to prepare and distribute safety technical instructions or warnings
and to ensure that the person concerned has received and understood it.
Warning: If the system is integrated into a machine or designed to be assembled, commissioning must not take place until the machine the system is to be integrated in conforms to the EC directives.
Prohibition of Unauthorized Modifications
System and accessories must not be changed either in construction nor safety
technology without the express consent of Brüel & Kjær Vibro. Any unauthorized
modification excludes Brüel & Kjær Vibro’s liability for resulting damages.
Application
The AS-668 is mainly used for the measurement of vibrations at rotating machines such as turbines, pumps, compressors, etc.
Measuring Principle
The acceleration sensor operates according to the piezo-electric principle. A
piezo element and an internal sensor mass form a spring-mass system in the
sensor.
If this system is subjected to vibrations the mass produces an alternating
force on the piezo element. As a result of the piezo effect, an electrical
charge is produced that is proportional to vibration acceleration.
An integrated amplifier converts this charge signal into a usable voltage
signal.
Mounting
Coupling
General rule:
The weight of the acceleration sensor should always be lower at least by a
factor ten than the weight of the object onto which it is mounted.
The acceleration sensor is an additional mass, which loads the object on which
it is mounted, and this changes the vibration behaviour if it is too large.
The sensor requires a friction-locked, contact resonance-free, rigid mounting
to the object, particularly for measurements at high frequencies. The cable
must be attached on a non-tension basis and load-free in connection.
The sensor must be mounted with one of the supplied screws (M6x1 – 30 mm length or ¼“ – 28 UNF x 1 1/4″ length). The mounting position on the machine is arbitrary.
- The mounting surface must be machined flat in the area of the sensor (roughness depth 0.8 µm, flatness 0,05 mm) and have a minimum diameter of 65 mm.
- Supply installation surface with threaded bore (M6x1 or ¼’’ – 28 UNF) according to drawing (fig.4-1).
- The bore must be countersunk and cleaned.
- Screw-threaded stud into installation surface according to drawing (fig. 4-1) and secure (LOCTITE 243 intermediate strength or LOCTITE 270 high strength).
- Apply thin layer of silicone grease to the installation surface to reduce contact resonance.
- Screw sensor onto the threaded stud with a mounting torque of 3.5 Nm and secure (LOCTITE 243 medium strength or LOCTITE 270 high strength).
EMV
EN 61326-1 Through electromagnetic stray fields, influences on the measured values may arise. In case of disturbing influences of this type, a grounded protective conduit is recommended for the signal cable.
Calibration
In the event of a calibration request, we offer the following services:
- Factory calibration by Brüel & Kjær Vibro
- Calibration traceable to national standards by our DAkkS accredited calibration laboratory
Disposal
After use, dispose of the systems, cables and sensors in an environmentally friendly manner, in accordance with the applicable national provisions. WEEE- Reg.-Nr. DE 69572330
Technical Data
Features
- Robust design
- M12 plug
- Constant current supplied General purpose
Applications
The sensor is suitable for the recording of high and low-frequency signals. Typical applications are, for example, the monitoring of transmissions or cooling fans in wind turbines, heavy-duty and planetary gears or large fans.
Product Description
Scope of delivery:
- Sensor AS-668 with socked head screw M6x1 – 30mm length according to ISO4762 (hexagon socket) and retaining washer pre-assembled
- Hexagon socket ¼’’ – 28 UNF x 1 1/4″ length enclosed
- Documentation
Connection
Plug connection (M12 male)
- Pin 1: SIG
- Pin 2: 0V / GND
- Pin 3: not connected
- Pin 4: not connected
The following performance data apply, to the extent that nothing else is indicated, under standard conditions (Ambient temperature = 25 °C, Constant current = 4 mA).
Dynamic
- Sensitivity, nom. (at 80 Hz): 100 mV/g ±10 %
- Frequency response: 0,5 Hz .. 13 kHz: ±3 dB 1,5 Hz .. 10 kHz: ±10 %
- Measurement range: 60 g Peak
- Resonance frequency: typically 30 kHz
- Amplitude linearity: < 1 %
- Cross sensitivity: typically 5 %
Electric
- Maximum output voltage: 27 V
- Constant current supply (secure against reverse polarity): 2 mA .. 10 mA (24 V nom.)
- Output resistance: 100
- Bias voltage: typically 12,9 VDC
- Across entire temperature range: 12,4 VDC .. 13,4 VDC
- Grounding: Housing isolated against sensor electronic
Surroundings
- Operating temperature range: -55 °C .. +125 °C
- Operating temperature with connection cable AC-140…: -30 °C … +90 °C
- Storage temperature range in original packaging: -20 °C .. +70 °C
- Overload capacity: Constant, sinusoidal: 500 g Shock: 5.000 g
- Housing design: Hermetically sealed stainless steel housing
- Degree of protection acc. EN 60529: IP68 (2 h at 5 bar) (incl. Nema 6) (only with connection cable AC-1403 or AC-1404)
Physical values
- Measurement principle: Piezoelectric principle, compression type
- Weight: 175 g
- Housing material: stainless steel 1.4404
- Mounting screw: ISO 4762 M6x1 – 30 mm length or¼’’ – 28 UNF x 1 1/4″ length
- Mounting torque: 3,5 Nm
- Connection: M12 plug, male, 4-pole
Order code
- AS-668
Accessories
- AC-1403: double-wired connection cable with straight plug (M12)
- AC-1404: double-wired connection cable with angled plug (M12)
Connection Diagram
CE Declaration
