Detcon FP-624C - Manual (Page 20)

magnet to make an adjustment to “PGM 1” to increase or “PGM 2” to decrease the display reading until the
reading is equal to the desired alarm set point. Exit to the programming menu by holding the programming
magnet over “PGM1” for 3 seconds, or automatically return to the programming menu in 30 seconds.
c) ALARM 2 LEVEL From the programming menu scroll to the alarm 2 level listing. The menu item appears as:
“SET ALARM 2 LEVEL”. Enter the menu by holding the programming magnet stationary over “PGM 1”
for 3 seconds until the display reads
“SET ALM2 @ 40%”, then withdraw the magnet. Use the programming
magnet to make an adjustment to “PGM 1” to increase or “PGM 2” to decrease the display reading until the
reading is equal to the desired alarm set point. Exit to the programming menu by holding the programming
magnet over “PGM1” for 3 seconds, or automatically return to the programming menu in 30 seconds.
d) Exit back to normal operations by holding the programming magnet over “PGM 2” for 3 seconds, or automati-
cally return to normal operation in 30 seconds.
3.10.2 Alarm Reset
An alarm condition will cause the applicable alarm to activate its corresponding relay and LED. If alarm 1, alarm 2,
or fault alarms have been programmed for latching relays, an alarm reset function must be activated to reset the
alarms after an alarm condition has cleared. To reset the alarms, simply wave the programming magnet over either
“PGM 1” or “PGM 2”, momentarily, while in normal operations mode and note that the corresponding alarm
LED(s) turn off.
3.10.3 Other Alarm Functions
Alarms are factory programmed to be non-latching, de-energized; and to f ire under ascending gas conditions. The
fault alarm relay is programmed as normally energized which is useful for detecting a 24VDC power source failure.
All alarm functions are programmable via jumper tabs. Changing alarm functions requires the sensor housing to be
opened, thus declassif ication of the area is required. See section 3.5.5-e for details.
3.11 P
ROGRAM
F
EATURES
Model FP-624C MicroSafe™ Sensors incorporate a comprehensive program to accommodate easy operator inter-
face and fail-safe operation. Program features are detailed in this section. Each sensor is factory tested, programmed,
and calibrated prior to shipment.
Over Range
When the sensor detects gas greater than 100% LEL, it will cause the display to f lash “100 % LEL” on and off.
Under Range Fault
If the sensor should drift below a zero baseline of approximately 10% of scale, the display will indicate a fault:
“SIGNAL FAULT”.
Open Sensor Bridge Fault
If either the active or reference side of the catalytic sensor bead should fail and become electrically open, the dis-
play will indicate a fault: “SENSOR FAULT”.
Sensor Heater Voltage Functions/Fault
The heater voltage is continuously monitored. The normal heater voltage is 2.7 VDC. If the voltage has drifted from
the programmed heater voltage value by more than ±.1V, the display will indicate a fault: “HEATER FAULT”.
Calibration Fault
If during calibration the sensor circuitry is unable to attain the proper adjustment for zero or span, the sensor will
enter into the calibration fault mode and cause the display to alternate between the sensor’s current status reading and
the calibration fault screen which appears as: “CAL FAULT”.
Model FP-624C Combustible Gas Sensor PG.20