18
2.
Acknowledgement of Alarms:
If an alarm condition occurs, the alarm (red) LED will
illuminate and the relay will be activated. To acknowledge an alarm (and deactivate the relay) for
all sensors in the “Alarm” condition press the
key. Pressing the
key once will inactivate
the horn, pressing the
key twice will inactivate the relay. Alarms can also be acknowledged
remotely through the use of a SCADA system / PLC. To do this, connect a contact input to the
DI1 input terminal on the 2 relay board (MB123) and to a relevant ground. Connecting the input
once will inactivate the horn, connecting the input twice will inactivate the relay.
Note: Even after acknowledging the alarm, both LEDs will remain illuminated until the alarm
condition has been removed.
3.
Alarm Explanation:
Rising and Falling Alarms
a.
Rising:
If the Danger (low level alarm) is set to a lower value than the Alarm (high
level alarm), then the GA-180 will automatically confi gure the channel as a rising alarm.
Therefore, if the sensor reading is higher than the Danger or Alarm setting the GA-180 will
activate the appropriate alarm(s). To confi gure a sensor rising/falling alarm, follow the steps
outlined in Section II-C.
b.
Falling:
If the Danger (low level alarm) is set to a higher value than the Alarm (high
level alarm), then the GA-180 will automatically confi gure the channel as a falling alarm.
Therefore if the sensor reading is lower than the Danger or Alarm setting the GA-180 will
activate the appropriate alarm(s). To confi gure a sensor rising/falling alarm, follow the steps
outlined in Section II-C.
c.
Failsafe Alarms:
If a sensor channel is set to failsafe, then the corresponding Alarm (high
level alarm) relay will become normally energized. This will cause a reversal of the NC/
NO connections. Therefore, the normally closed connection will be open unless an alarm
condition is present or power is lost. To confi gure a sensor failsafe alarm, follow the steps
outlined in Section II-C.
4.
4-20 mA Outputs:
The GA-180 also includes isolated 4-20 mA outputs for each channel
ordered. This output signal will represent the current gas residual value. See Figure 6 for
4-20mA output wiring locations.
