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GMW20
User Guide
12 pgs753.6 Kb0
User Manual
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Table of contents
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vaisala GMW20 User Guide

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User’s Guide
www.vaisala.com
Vaisala CARBOCAP® Carbon Dioxide Transmitter Series GMW20
M210196EN-B
Table of Contents
Basics of the GMW20 Series ................................................ 2
Mounting...................................................................................... 2
Electrical Connections............................................................4
Power Supply Requirements................................................ 5
Technical Data ........................................................................... 7
Relays and Other Accessories............................................. 8
Dimensions (in Millimeters)................................................... 9
1

Basics of the GMW20 Series

Vaisala’s GMW20 series transmitters use silicon based CARBOCAP properties. The series consist of the following transmitter types:
GMW21 and display version GMW21D (80x108.5x35) mm GMW22 and display version GMW22D (80x80x35) mm
sensor with excellent stability and reliability
The GMW20 series transmitter is calibrated as shipped from the factory. In benign environments the recommended calibration interval is five years. In case adjustment is needed, contact Vaisala Service or local Vaisala representative.
The reading of the GMW20 can be checked and adjusted with the serial com adapter 19040GM and the calibration software available from www.vaisala.com. The checking in the field can also be done with calibration gas and a multimeter.

Mounting

1. The GMW20 is shipped ready for installation onto a
standard wallbox or onto a surface mounting.
2. Drill a hole in the surface where the transmitter will be
mounted , then pull the wiring through the drilled hole.
3. Open the transmitter cover by pushing forward and
turning a screwdriver head in the slot located at the bottom between the cover and the back plate.
4. Remove the printed circuit board (PCB) by pressing
upwards with a screwdriver (see Figure 1 on page 3).
2
Figure 1 Cable routing
5. Thread the power wires and output signal wire through
the center hole of the back plate. In case of surface wiring, make (e.g.with a pliers) cut-out by removing the attenuated part at lower edge of the back plate.
6. Center the hole in the base over the drilled holes and
fasten the base to the surface by using the screws.
7. Install the PCB into the base by aligning it over the latch
pins and press down the upper right corner until it snaps into place. When using GMW21D or GMW22D, mount the display module on top of the PCB.
8. Proceed to the
Electrical connections
section.
3

Electrical Connections

See the requirements for the power supply in the Technical Data section.
1. Connect the nominal 24 V supply on the PCB between the
terminals + and -. Connect the common wire to terminal 0 and the other wire either to terminal V (voltage output) or to the terminal mA (current output).
2. Choose the current output with the jumper 0/4 mA
– 4 ... 20mA: jumper shorts the pins (default) – 0 ... 20 mA: disconnect (do not discard) the jumper.
3. If the unit has an optional accessory (relay, display and
relay, LonWorks interface, or temperature module), follow the procedure described in the applicable manuals before repositioning the cover.
4. Reposition the cover.
Power supply terminals
Current
output
jumper
Figure 2 Jumper and Terminals
Connecting power wires to the output terminal can seriously damage the product.
4
Output s ignal terminals

Power Supply Requirements

The GMW20 uses a nominal 24 VAC/VDC power supply maintaining a voltage of 18...30 VDC or 20...26 VAC for all load conditions and all mains voltages. Although the power input includes a halfwave rectifier, it is recommended to use a DC supply to avoid current peaks (Current consumption: peak 170 mA, average 85 mA).

Connections to a 24 VAC Power Supply

When more than one transmitter is connected to one 24 VAC transformer, a common loop is formed and the risk of a short­circuit increases. To avoid this, separate floating supply for each transmitter is recommended (see Figure 3).
In case where several transmitters have to share one transformer, the phase ( connector in each transmitter to maintain the "polarity" and to avoid short-circuit via shared common line at the controller as shown in Figure 4.
) must always be connected to 24V
5
O
R
CONTROLLER
Signal output
24VAC
Supp ly voltage
GMW20
24V OUT
GND
GMW20
24VAC
Supp ly voltage
24V OUT
GND
Signal output
Figure 3 Connection of separate AC supplies (recommended)
GMW20
24V AC
Supply voltage
Supply voltage
Figure 4 Connection of one AC supply to several transmitters
24V OUT
GND
GMW20
24V OUT
GND
Signal output
Signal output
NTROLLE
C
SHAR E D COMMON LINE
6

Technical Data

Property Description / value
Measuring ranges 0 ... 2000 ppm CO2
Accuracy at 25 °C against certified factory references (includes repeatability and calibration uncertainty) Long-term stability < 5 % of range / 5 years Response time (0 ... 63%) 1 minute Warm-up time 1 minute
Operating temperature range -5 … +45 °C (+23 … +113 °F) Storage temperature range -20 ... +70 °C (-4 … +158 °F) Humidity range 0 ... 85 % RH , non-condensing Output signal for CO2 Selectable 0...20 mA or 4...20 mA
Resolution of analog outputs 8 bits Optional outputs Relay output
Recommended external load current output voltage output Power supply nominal 24 VAC/VDC
Power consumption < 2.5 W Housing material ABS plastic Housing colour NCS 0502-G50Y
0 ... 5000 ppm CO 0 ... 10 000 ppm CO 0 ... 20 000 ppm CO
2
2
2
(2 % of range + 2 % of reading)
15 minutes full specifications
and 0...10 V
LonWorks® interfaces
max. 500 min. 1 k
(18 ... 30 VDC)
7
Wei ght GMW21 GMW21 with display GMW22 GMW22 with display
100g 130g 90g 120g

Relays and Other Accessories

Transmitters can be ordered with or without relays. The default relay trigger point has been set to 1000 ppm. This can be changed with the optional software kit 19222GM.
Description Or der Code
Display and relay output option GMI21 Relay output option GMR20 LonWorks module with CO2 signal (Not available when display option is added) LonWorks module with both CO2 signal and temperature signals (not available when display option is added) Analog temperature module for GMW21 (not available when display option is added) Serial COM adapter 19040GM Hand-held meter for field verification GM70
GML20
GML20T
GMA20T
8

Dimensions (in Millimeters)

80
60
83
108.5
66.7
Figure 5 GMW21 and GMW21D
80
60
80
Figure 6 GMW22 and GMD22D
9
66.7
Legal notice
© Vaisala 2010 No part of this manual may be reproduced in any form or by any
means, electronic or mechanical (including photocopying), nor may its contents be communicated to a third party without prior written permission of the copyright holder.
The contents are subject to change without prior notice. Please observe that this manual does not create any legally binding
obligations for Vaisala towards the customer or end user. All legally binding commitments and agreements are included exclusively in the applicable supply contract or Conditions of Sale.
Warranty
For warranty information, visit our Internet pages at
www.vaisala.com/services/warranty.html
This product is covered by an extended 2 year warranty
Technical Support
For technical questions, contact the Vaisala technical support via email:
helpdesk@vaisala.com
For contact information of Vaisala Service Centers, see
www.vaisala.com/services/servicecenters.html
*M210196EN*
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