MGS-250 Manual
6490-9000 Revision 4
31
4.4. Alarms
The following occurs during an alarm condition.
Table 9: MGS-250 Behavior during Alarm Conditions
Item
Behavior During Alarm State
Green LED
On (solid)
Display
On (blinks); reports detected PPM concentration
Audible Alarm
On (if enabled and after programmed delay
expires)
Relay Output
Activates (after any programmed delay expires)
Analog Output
Changes proportionally with gas concentration
(as configured)
Modbus Registers
Registers indicate the alarm condition, ppm
concentration, etc.
NOTE:
The alarm feature includes a 20% dead band to
prevent alarm ‘chatter’ if the concentration hovers near the
alarm setpoint. Once the alarm has been triggered it will
remain latched until the concentration drops below 80% of
the alarm setpoint.
4.5. Gas Detector Faults
4.5.1. Overview
There are two levels of fault monitoring built into the gas detector.
x
Non-critical
x
Critical
4.5.2. Non-Critical Faults
Non-critical faults typically recover by allowing the gas detector
surroundings to stabilize, for example, after a defrost cycle. The gas
detector continues to monitor its surroundings during non-critical faults,
but may report inaccurate readings.
The following occurs when a non-critical fault condition exists.
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