Detcon TP-624C - Manual (Page 19)

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 @ ##PPM” , then withdraw the magnet. Use the program-
ming 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.
3.9.2 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”, momentar-
ily, while in normal operations mode and note that the corresponding alarm LED(s) turn off.
3.9.3 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 3.5.4-e for details.
3.10 P ROGRAM F EATURES
Detcon MicroSafe™ H2S gas 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 its selected full scale range (20, 50, or 100 ppm), it will cause the display to f lash
“20/50/100 PPM H2S” on and off.
Zero Fault
If the sensor does not clear to <10% of range in <5 minutes after completing a span calibration, the sensor will
enter into a calibration fault mode which will cause the display to alternate between “ZERO FAULT” and the sen-
sors current reading.
Range Fault
If the sensor fails the minimum signal change criteria, then a “RANGE FAULT” message will be displayed.
Open Heater Fault
If the sensor heater should fail and become electrically open, the display will indicate a fault: “HEATER FAULT”.
System Fault
If the detector has an irrecoverable calculation error, the display will indicate: “SYSTEM FAULT”.
Sensor Heater Voltage Fault
Approximately one minute after start-up, the sensor will check the heater voltage. Normal heater voltage is 5.25
VDC. If the voltage drifts from this value by more than ±.3V, the display will indicate a fault: “HEATER
FAULT”.
Fail-Safe/Fault Supervision
Model TP-624C MicroSafe™ sensors are programmed for Fail-Safe operation. Any of the following fault conditions
will activate the fault relay, illuminate the fault LED, and cause the display to read its corresponding fault condition:
“RANGE FAULT” , “ZERO FAULT” , “HEATER FAULT” , or “SYSTEM FAULT” . A “Heater Fault”,
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.19