Gas Detection (Australia) Pty Ltd Page 7 of 11 M-GDA-40125-06/08/2018
8. If the unit looses power the FAULT relay, which is normally activated, will deactivate.
The FAULT relay will also deactivate if the sensor encounters an abnormal condition
or the internal electronics fail
9. Pressing the mute button in any state will not deactivate the alarm relays.
10. 4-20mA o/p
This o/p represents the sensors current o/p of the toxic gasses detected in its
range or the current level of oxygen present. The 40125 can drive into a
maximum loop impedance of 800R. The o/p is NON ISOLATED. Care must be
exercised when 0V referencing the sensor to other apparatus so as not to
inject ground (0V) noise into the 40125. The connecting equipment should
not use an earth tied 0v line. GDA recommends the use of The GD 690
Galvanic isolator in the 4-20mA o/p in safety critical applications
Response time . The sensor is a electrochemical sensor which the Toxic gas or oxygen has to
naturally diffuse into. The sensor response time to gas is <10 seconds. However it may take
longer to diffuse through the sensor and displace all the gas in the electrochemical sensor as
the sensor uses natural diffusion to allow gas into the chamber.
Setup:
ALL systems are factory set up with the sensors ordered and this section will not have to
be followed
To enter setup mode, jumper the right most pins on P7. (On the Setup Option)
Use S1 and S2 to change the setup options. S1 (Top most button) is down while S2 (Bottom
most button) is set.
To change the setting, press the DOWN button, (some settings allow the value to be
incremented by larger steps when the Down button is held for at least 1 second) when the
correct value is indicated press the SET button this saves the selected value to unit and
moves to the next setting option.
If the setup jumper is removed, the current setting will NOT be saved to unit., only pressing
the SET button will save the value If a mistake is made, then removing the jumper will not
save that value.
The setting and its current value is displayed on the screen. During setup no alarms will
sound or relays activated except the Fault relay.
After Setup is complete remove jumper link from board.
