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3.2 Initial Application of Power
Bef ore applying power for the first time, double-check all wiring components.
The system has a time delay feature. The High and Low alarm circuits are disabled for
approximately 45 seconds after power is applied. This feature prevents false alarms while
the sensor circuits are stabilizing.
At the initial application of power, the unit will enter a 45-second start-up mode. During
this time, the display will read “SU”. The unit will then enter operational mode and the
current gas concentration of the sensor will display. If a channel fault occurs, the FAULT
LED will flash, the fault relay will become active and the unit will display the ap propriate
error code. This fault indication is independent of the abovementioned time delay feature.
NOTE: A defect in one sensor circuit does not affect the operation of the other channels.
3.3 Resetting Latched Alarms
The user may select a latching or non-latching alarm output for High and/or Low alarms.
If an alarm output activates and the condition that caused that activation is no longer
present, a non-latching alarm output resets automatically. A latched alarm output needs
to be reset manually.
Resetting latched alarm outputs is done with the Reset button located on the c hannel 1
(CH1) board. Pressing the Reset button resets any latched conditions that are no longer
valid.
EXAMPLE: The sensor detects a gas concentration in excess of an alarm set point. The
associated alarm outputs activate. Af ter a f ew moments, the gas
concentration drops below the alarm set point. If the alarm outputs are
latched, the operator can press the Reset button and the latched alarm
outputs return to the normal (safe) state.
3.4 Analog Output
The Analog Output is a 0 to 21.7mA current signal with 4 to 20mA being proportional to 0
to 100% of full scale.
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