mPower Electronics Inc MP820 VOXI LEL Fixed Electrochemical Gas Detectors User Manual

mPower Electronics Inc MP820 VOXI LEL Fixed Electrochemical Gas Detectors

Read Before Operating

This manual must be carefully read by all individuals who have or will have the responsibility of using, maintaining or servicing this product. The product will perform as designed only if it is used, maintained and serviced in accordance with the manufacturer’s instructions. The user should understand how to set the correct parameters and interpret the obtained results.

WARNINGS!

• Never operate the monitor when the cover is removed.
• Remove the monitor cover only in an area known to be non-hazardous.
• Use only mPower’s sensor and accessories. Substitution of components will impair suitability for intrinsic safety and void warranty.
• The instrument should be calibrated after installation before initial use and checked by exposing it to a known concentration calibration on a regular basis.
• Ensure that the gas inlet is not blocked.
• Make sure that all filters are clean and replaced on a regular basis.
• Remove the sensor only if necessary for repair. Zero and span calibration are required once the sensor is moved.

Special Conditions for Safe Use

The VOXI monitor must be calibrated if it does not pass a bump test, when a new sensor has been installed, or at least once every 180 days, depending on use and sensor exposure to poisons and contaminants.

General Information

The VOXI LEL MP820 is a point-type combustible gas transmitter designed with pellistor sensor technology and an integral flameproof enclosure for fixed applications. The versatile platform offers auto-zeroing and offline calibration. Three-wire 4-20 mA analog and RS485 digital signal outputs are standard, while wireless output is optional. Three sets of programmable relays allow triggering of external alarms such as a siren or visual beacon. Various applications include oil & gas, petrochemical, chemical, metallurgical, pharmaceutical, semiconductor, environmental monitoring, and other industry facilities.

Key Features

• Supporting catalytic combustion LEL sensors with identification and manufacturing data
• Sensor diagnosis, temperature compensation and auto-zeroing
• LCD with backlight that changes color according to alarm condition
• Calibration due date notification
• 3 Wires for 4-20 mA and RS485 ModBus output
• Infrared remote programmer for settings, calibrations and adjustments
• Error codes for easy troubleshooting
• Recoverable factory settings
• Overrange protection, reverse polarity protection
• IP-67 rating
• IECEx certification
• Optional ISM 915 MHz modem for wireless connectivity at no subscription fee

User Interface

The VOXI user interface consists of one large LCD Display showing the gas concentration, a power status LED, an alarm LEDs, and a fault indicator LED. Calibration is performed and operating parameters are entered using a handheld IR remote programmer.

Backlight changes color to indicate alarms or faults

Installation

WARNINGS !

• The VOXI LEL has CNEX and IECEx certifications for use in hazardous gas locations. Check for certification requirements before installing.
• The VOXI LEL has NO HAZARDOUS GAS CERTIFICATION when used with 163500 cable for oil and water.
• Before installation, ensure that all power is disconnected.
• Before removing the monitor cover for service, disconnect the power supply and ensure that the area free of combustible gases and vapors.
• For European locations, installation must comply with EN-60079-14.
• The instrument should be calibrated after installation before initial use and checked by exposing it to a known concentration calibration gas on a regular basis.
• Remove the sensor only if necessary for repair. Zero and span calibration are required once the sensor is moved.

Mounting

Mounting Location

Because the VOXI LEL samples by diffusion, it should be installed directly in the area to be measured.*1 For an entire room to be monitored, there is a reliance on good air circulation within the room, since the VOXI can only measure in the immediate vicinity of its inlet. If the VOXI must be mounted remotely, the gas must be pumped to the inlet because it has no sampling pump of its own.

Mechanical Mounting Options

The VOXI LEL is designed for wall mount or pole mount using the screw-holes provided, centered 5.25 inches or 134 mm apart. An optional mounting bracket (P/N M024-3003-000) is available that allows the unit to be offset about 1 cm from the wall or pole.

If mounted outdoors, ensure that the gas inlet is directed downwards and the raincap is installed to minimize the chance of precipitation entering the sensor inlet.

**The shape and dimensions of VOXI are shown in the figure below:

**

• **Wall Mount

**

• **Pole Mount

**

• **Bracket Dimensions (mm)

**

*1 Future VOXI LEL versions that have certifications will be able to be installed and operated in hazardous-gas locations, but because the housing cannot be opened for service in the presence of flammable gases, the VOXI LEL is easier to maintain if installed in a non-hazardous location or an area that can be vented to remove hazardous gases before opening the housing.

Rain Cap

If mounted outdoors, the rain cap should be installed to reduce the chance of precipitation ingress. If mounted indoors, the rain cap may be removed.

Electrical Connections

Internal Wiring

Four openings are provided in the explosion-proof housing, covered by hex-head plugs which can be removed to attach conduit for remote wiring, alarm beacon, antenna, and/or other wire connections. For internal connections, unscrew and remove the cover by first loosening the lock screw located on the side, using an Allen wrench. Pinch the buckles on both sides of the instrument assembly to release and then lift it out. Unplug the sensor plug from the PC board.

The schematic below shows the internal wiring connections. Insert the wire through the conduit hole and connect to the corresponding pin numbers of the three terminal blocks on the bottom of the assembly. These blocks accept 12AWG to 24AWG wire (0.2 to 4.0 mm2 ). Input power requirements are <5W, 12-30 VDC and should be connected between Terminals 14-GND and 15-V+.

FAULT
9| 10| 11| 12| 13| 14| 15
---|---|---|---|---|---|---
COM| RS 485A| GND| RS 4858| 4-20mA OUTPUT| GND| -‘-V

Alarm outputs on Terminals 6-9 are normally-open dry contacts that close on alarm. The 4-20 mA output should be connected to Terminals 13 and 14. RS485 should be connected to terminals 10 & 12, and terminal 11 is for the RS485 shielding line. The +V terminals 5 and 15 are equivalent and internally connected, as are GND terminals 11 and 14.

Grounding

The internal ground point is shown in the left figure below. An external ground wire (AWG11 recommend) should be connected to the VOXI housing (right figure below).

Maximum Wiring Length

The maximum signal transmission distance can be estimated from the resistance of the shielded cable, allowing for a maximum of 150 Ω, as shown below (actual maximum distance may vary).

WARNING !

• The VOXI LEL has NO HAZARDOUS GAS CERTIFICATION when used with 163500 cable for oil and water.

Baseline 4 mA Signal Adjustment

If sending the 4-20 mA signal to a remote controller, during the field installation the VOXI LEL analog output should be adjusted. See VOXI LEL Programming section below for procedures.

MODBUS Message RTU Framing

The VOXI uses RTU framing for MODBUS messages. The following is an excerpt of the MODBUS over Serial Line Specification and Implementation Guide v1.02 (Dec.2006) with more information available at http://www.modbus.org/ and http://www.modbus.org/specs.php :

A MODBUS message is placed by the transmitting device into a frame that has a known beginning and ending point. This allows devices that receive a new frame to begin at the start of the message, and to know when the message is completed. Partial messages must be detected and errors must be set as a result. In RTU mode, message frames are separated by a silent interval of at least 3.5 character times. In the following sections, this time interval is called t3,5.
RTU Message Frame

The entire message frame must be transmitted as a continuous stream of characters. If a silent interval of more than 1.5 character times occurs between two characters, the message frame is declared incomplete and should be discarded by the receiver.

Remark: The implementation of RTU reception driver may imply the management of a lot of interruptions due to the t1.5 and t3.5 timers. With high communication baud rates, this leads to a heavy CPU load. Consequently, these two timers must be strictly respected when the baud rate is equal to or lower than 19200 Bps. For baud rates greater than 19200 Bps, fixed values for the 2 timers should be used: it is recommended to use a value of 750 µs for the inter-character time-out (t1.5) and a value of 1.750 ms for inter-frame delay (t3.5)

Operation

Standard Operation

Once installed and power is turned on, the VOXI LEL cycles through a start-up sequence (below).

After start-up, the VOXI LEL samples the gas by diffusion and runs continuously to measure the toxic gas (or oxygen), display the concentration readout and any alarms, and send any output and alarm signals to external devices. When an alarm level is exceeded, the Alarm LED flashes and the display backlight changes color.

Programming using Hand-held Remote

Configuring and calibrating the VOXI LEL is done using a handheld remote programmer. There is no magnetic key or other means of programming the VOXI LEL directly. Communication with the transmitter functions from up to 3 m (10 ft) distance when directed straight at the transmitter display instead of from an angle.

WARNING!

• VOXI LEL monitoring is turned off during communication with external devices.
• Perform programming and calibrations only during times known to be free of toxic or combustible gases and vapors.

Battery Installation

The remote programmer uses a CR2025 3V battery or equivalent. To remove or replace the battery, place the unit face down, push the retaining hook inward and slide out the battery holder.

User Interface

Press the Main Menu Access button on the Remote Programmer to display the user interface on the VOXI LCD. Program operations can be selected using the cursor movement arrows. Shortcut operations can be conducted using the Zero and Span buttons to quickly perform routine zero and span calibrations. The firmware is factory-set and currently cannot be changed by the user.

Navigating Menus and Sub-menus

Press the Main Menu Access button and use the Up and Down arrows to scroll through the menu. Use the Right and Left arrows to enter or exit a menu item. When entering numerical values, use the Left or Right arrows to move the cursor, and the Up and Down arrows to increase or decrease the values, When the cursor is moved to the “?”, press OK to save or enter. To exit a sub-menu, press the cancel key . To exit the Main Menu, scroll down to the EXIT screen and press OK. The display will also automatically return to concentration readings after about a minute of non-use.

• Enter the menu:
  

• Enter the password and press OK:
  

• Scroll through the menu:
  

• **Exit the menu:

**

BASIC and ADVANCED Menus

There are two menus

• Basic Menu is accessed using default Password 0000. This allows basic field operations such as calibration, setting alarm levels, and communication with PC for firmware upgrades
• Advanced Menu is accessed using default Password 8888. This allows access to additional advanced features such as changing passwords, changing concentration units, baud rate for wireless, setting location ID, etc.

The Basic Menu and sub-menus are listed below

Display| Main Menu| Sub-Menu 1| Sub-Menu 2| Sub-Menu 3
---|---|---|---|---
CAL| Calibration| Zero Calib| Span Calib| Set Span Value
ALM| Set Alarm Limits| Low Alarm| High Alarm|
COMM| Communicate to PC (Factory & Service use only)
EXIT| Exit| | |

The table below lists all Advanced Menus and their sub-menus.

Display| Main Menu| Sub-Menu 1| Sub-Menu 2| Sub-Menu 3
---|---|---|---|---
CAL| Calibration| Zero Calib| Span Calib| Set Span Value
**JOIN*| Join Wireless Network| | |
ALM| Set Alarm Limits| Low Alarm| High Alarm| Range
CF| Set Correction Factor| | |
PSWD| Set Password| Basic Password| Adv. Password|
BPS| Set Baud Rate| | |
4 __ 20| 4-20 mA Adjust| 4 mA Adjustment| 20 mA Adjustment|
SITE**| Set Site ID| | |
RST| Reset to Default Values| | |
COMM| Communicate to PC (Factory & Service use only)
EXIT| Exit| | |

• JOIN menu is shown only for wireless versions

The Advanced Main Menu path is shown below

Calibration (CAL)

Perform zero and span calibrations. See the following Calibration Section for details.

Join Network (JOIN)

Join a wireless network for communication up to 1 mile (1.6 km) away using an mLink modem. This menu is visible only with wireless systems.

Alarm (ALM)

Set the numerical values for the low and high alarm limits.

Correction Factor (CF)

A correction factor can be used when the calibration gas is different from the measured gas.

Password (PSWD)

Change the passwords for either Basic or Advanced configurations.

Baud Rate (BPS)

The Baud Rate options are 4800, 9600 and 19200 bps and should be set to match that used in the MODBUS messaging protocol.

Analog Output (4_20)

If sending the 4-20 mA signal to a remote controller, during the field installation the VOXI analog output baseline should be adjusted. Read the current on terminal 13 using an ammeter while adjusting the raw counts. The default values are 530 counts for 4 mA (0 ppm) and 2600 counts for 20 mA. No gas needs to be applied during these operations.

Site ID (SITE)

Label the station or location.

Reset (RST)

Reset all parameters to their default values.

Communication (COMM)

Communication to PC for firmware upgrade, sensor firmware change, Modbus setting, etc. This feature requires special software currently available only to authorized service centers.

Default Settings

Sensor| Span Value ‡| Low Alarm ‡| High Alarm ‡
---|---|---|---
LEL| 50% LEL| 10% LEL| 20% LEL

Calibration

1. Before calibration, it is good practice to examine the inlet filter and replace as needed.
2. Zero Calibration: Scroll to the CAL ZERO menu. Alternatively, press the short-cut “Zero” button on the programmer. Supply clean air to the inlet. If the VOXI EC is mounted in an area where ambient air contains detectable concentrations of gases, attach the calibration cup and supply clean gas (air) directly from a cylinder fitted with a fixed-flow regulator of about 0.3-0.6 LPM. If no calibration cap is available, the rain cap may be used. Connect the zero gas directly to the rain cap.
3. For Oxygen sensors, the zero gas is ambient air (20.9% O2) and the default span gas is 18% O2, but span can be changed to 0% O2 for inert atmosphere applications.
4. Click ‘OK’ to initiate the 30-second count-down timer, after which Pass or Fail is displayed. Click ‘OK’ to move to Span or continue to Exit.
5. To abort, press during the count-down.

Or, using the short-cut Zero button on the remote programmer:

6. Span Calibration: Scroll to the CAL SET menu and ensure that the Span Gas setting matches the concentration of the gas in the calibration cylinder.

7. Scroll to the CAL SPAN sub-menu. Alternatively, press the short-cut “Span” button on the programmer. Attach the calibration cup and supply span gas directly from a gas cylinder fitted with a fixed-flow regulator of about 0.3-0.6 LPM to the inlet. Click ‘OK’ to initiate the count-down timer, after which Pass or Fail is displayed. The count-down time depends on the type of sensor and is typically about 45 seconds.

8. To abort, press during the count-down.

9. Use of fixed-flow regulators below 0.3 LPM or above about 0.6 LPM may cause poor calibration. A regulator with flow higher than 0.6 LPM can be used if an open T fitting is placed in line between the regulator and VOXI LEL inlet to allow excess gas flow to escape without being forced through the instrument.

10. The Calibration Interval should be at least every 6 months. However, the interval must be defined by the user and may be shorter because it depends on the application and local conditions. We recommend starting with weekly bump tests to check the response of the sensor and need for filter changes, and then increasing the length of time between checks and calibrations as experience is gained in the application. In all cases calibration should be performed at least every 180 days. See mPower TA Note 3 for more details.

Maintenance

The VOXI LEL requires regular sensor replacement if used in areas of high dust or condensation. Sensor life is typically 1-2 years depending on operating conditions.

Sensor Replacement

To comply with intrinsic safety requirements, the LEL sensor comes completely sealed with the inlet metal frit and the wiring plug. For replacement, the entire sensor must be disconnected from the circuit board and unscrewed from the housing.

Replace sensor only in non-hazardous environments.

1. Remove the rain cap (if used), unscrew the enclosure cap, and remove the LCD/circuit board assembly.
2. Disconnect the sensor cable plug from the LCD/circuit board assembly.
3. Using a large wrench, unscrew the LEL sensor from the enclosure.
4. Screw in a new LEL sensor assembly, tighten to the enclosure, and reassemble in reverse order/

IMPORTANT! Always perform a full calibration after removing a sensor.

LCD or Circuit Board Replacement

The entire LCD/Circuit board assembly must be replaced as a unit as they cannot be separated, as follows:

1. Open the housing and remove the cover and circuit board/LCD assembly as described above. Disconnect the wiring plugs
2. Replace the Circuit Board/LCD assembly and re-assemble in reverse order.

Troubleshooting

Solution: Check or replace sensor
Error Code E003| Reason: Unsupported Sensor
Solution: Replace sensor with a supported type or upgrade to firmware that supports the sensor
Readings abnormally High| Reasons: Dirty inlet. Dirty sensor module. Excessive moisture or water condensation. Incorrect calibration. Cross- sensitive gases present.
Solutions: Clean or replace sensor module. Calibrate the unit. Install in area without cross-sensitive gases.

Readings abnormally Low

| Reasons: Weak or dirty sensor. Incorrect calibration. Insufficient oxygen present.
Solutions: Clean or replace sensor module. Calibrate the unit. Ensure at least 5% Vol oxygen is present.
Cannot communicate with IR Programmer| Reasons: Programmer battery dead. Pointing from angle.
Solutions: Replace battery. Point straight at VOXI.
Cannot communicate with mobile device| Reasons: Non-Android operating system.
Android OS before 6.0 or recent background update Solutions: Use Android mobile device.
Restore OS to that used before update (at least v 6.0)
Lost password| Solutions: Call Technical Support at 408-320-1266

4-20 mA Alarm Signals

To aid in troubleshooting, in addition to display text and LEDs, the 4-20 mA output identifies some alarms, as follows:

potential threat to impact sensor output, including:

1. Hardware failures: including pump, sensor, any other hardware failures. Low input voltage, main power lost (if with backup battery), sensor NEG, sensor removed, etc.
2. CAL failure

3mA| Transmitter is in menu, including in “Cal” mode during Zero or Span Cal
4~20mA| 4mA: Sensor reading 0;
20mA: Sensor reading full scale
22mA| Over-Range Fault when reading is 10% over full scale.

NOTE: If a Cal Failure has been corrected with a good calibration after the cause is corrected, everything should proceed normally. If parts are replaced while the transmitter is off, it should still be in Cal Failure until a good calibration is performed after restart. Exception: If the sensor is replaced and the calibration data are stored on the sensor microprocessor, then it will likely reboot with no fault. However, it will still be preferable to perform a good calibration for the local  ambient atmosphere and conditions.

Technical Specifications

Detector Specifications

Digital RS-485,
ModBus
3 Relays
Wireless ISM 915MHz (optional) 1 mile tine of sight
Alarms| LCD & LED flashing, relays for external alarm devices
Housing| Explosion-proof aluminum alloy
Housing Entries| 4 Conduit entries ¾” NPT 1 Port M28x1 fitting
Installation| Pipe bolt and wall mount
IP Rating| IP-67
EMI/RFI| Compliant with EMC Directive 2014130/EU
Safety Certifications| IECEx
Ex db IIC T6 Gb (non-Wireless)
Ex lb IIIC rso·c Db (non-Wireless)
Ex db ia IIC 16 Gb (Wireless)
Ex ia lb IIIC T80PC Ob (Wireless) CNEX
Ex d IIC T6
Installation| Pipe holding, wall mount
Warranty| 2 Years

Sensor Options

Dimension in mm [inches]

Power and output connections

Standard

• Gas Transmitter with Sensor installed
• Rain Shield & Calibration Cap
• Infrared Remote Programmer
• Mounting Parts
• Quick Start Guide
• Calibration Certificate

Optional

• ISM 915 MHz Modem with Antenna

All specifications are subject to change without notice. Please check for updates at www.mpowerinc.com.

Replacement Parts

Enclosure , explosion-proof, for VOXI EC/LEL incl. housing bottom, top & O-ring| M024-3008-000| $125.00
Enclosure connector, 3/4″ NPT for VOXI EC/LEL| M490-0146-000| $20.00
Replacement circuit board/LCD Assembly for VOXI LEL| M026-3001-000| $150.00
Power Supply, 120-240VAC to 24-VDC, 1 W, with US wall plug for non-hazardous locations| M500-0039-000| $35.00

• LEL Sensor Module

• Calibration Cap

• IR Programmer

• Mounting bracket

• VOXI Enclosure

• Enclosure Connector (circled in red)

• Main PC board with LCD display assembly

• Rain Cap

Customer Support

Technical Support and mPower Contacts

mPower Electronics Inc.
2910 Scott Blvd. Santa Clara, CA 95054
Phone: 408-320-1266
Fax: 669-342-7077
info@mpowerinc.com
www.mpowerinc.com

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