PT900-12 Monitor/Controller
Rev 2.0
16
Alarm Bypass
In the Alarm Bypass mode the monitor will not activate the alarm relays if
any of the sensor reading exceeds the programmed alarm level. However,
the visual alarm LED indicators will be activated.
To put the alarms in bypass mode move the ALARM toggle switch on the
front panel of the control module to BYPASS position. If the gas reading
is above alarm level the visual alarm LED indicators will flash once every
second indicating that the alarms are in bypass mode. The switch must be
returned to NORMAL to end alarm bypass mode and for normal
operation.
Programming Alarms
Alarm levels must be programmed in order to activate the dry relay
contacts on the main control board. Alarm levels can be set anywhere
between 0 and the full scale of the sensor. Alarm relays can also be
selected as Latching or non-latching type. Also jumpers on the control
module can be selected to program the relay contacts to be
Normally Open
or
Normally Closed.
If any alarm level is set to 00 then that relay will not be activated any time
during normal operation.
Note
Non-Latching alarm is self resetting. Alarm relay will be de-activated if gas
concentration falls below the alarm set point.
Latching alarm on the other hand will not self reset if concentration falls
below alarm set point. The alarm relays must be manually reset by pressing
the RESET switch on the front panel
