Specifications

M GD-100 M anual

36 6109-9000 Rev 3

Step Electrical Re set of One-Alarm Systems

Connect a voltmeter between Pins 4 (-Ve) and 2 (+Ve) of the

sensor terminal connector block for each channel in turn

(CN1, CN2, etc.) and adjust the corresponding calibration pot

(P1, P2, etc.) to the sensor standby voltage (SSV) value as

per calibration label on side of enclosure. (For IR sensors,

set SSV to 2V.) See Figure 13 and Figure 15.

The alarm threshol d volt age (A TV) is the voltage at which the

alarm and relay acti vat e at a given gas concentration. This

voltage is normally set to 3.0V at the factory and is adjusted

using:

• pot “P3” for 1- or 2-c hannel units (see Figure 1)

• pot “P7” for 4- or 6-c hannel units (see Figure 2)

Measure bet ween pi ns 4 (-Ve) and 1 (+Ve) on the Cal

header. See Figure 13 and Figure 15.

For the al arm set point, connect the DC voltmeter between

0V (TP5) and High (TP1) (see on page 10). Adjust P7 to the

alarm set poi nt as per the rating label (normally 1.2V ).

Carry out a bump test to ensure the sensor is functioni ng

correctly.

If the sensor does not go into alarm, carry out a gas

calibration.

Finally, return jumper JP1of the controller to its original

position.

6.3. Electrical Reset of Two-Alarm Systems

Reset, if necessary, the Standby and low /high Alarm Threshold Voltages

to the factory settings as shown on the calibration label. This is

performed on the sensor P CB.

Electrical reset information is listed on the label on the side of the

enclosure and is unique to that sensor.

Tools required:

• A voltmeter (crocodile clips recommended)

• Factory set point electric values (as shown on the rating label)

• Screwdri ver (depending on enclosure).