Fail-Safe/Fault Supervision
Model TP-524C MicroSafe™ sensors are programmed for Fail-Safe operation. Any of the following fault conditions
will illuminate the fault LED, and cause the display to read its corresponding fault condition:
“RANGE FAULT”
,
“STABILITY FAULT”
,
“ZERO FAULT”
,
“HEATER FAULT”
, or
“SYSTEM FAULT”
. A “Heater Fault”,
“System Fault”, “Zero Fault”, and “Range Fault” will also cause the mA output to drop to zero (0) mA until the
condition is corrected.
Sensor Life
The sensor life feature is a reference based on signal output from the sensor cell. When a sensor life of 25% or less
remains, the sensor cell should be replaced within a reasonable maintenance schedule.
3.10 D
ISPLAY
C
ONTRAST
A
DJUST
Model TP-524C MicroSafe™ sensors feature a 16 character backlit liquid crystal display. Like most LCDs, character
contrast can be affected by viewing angle and temperature. Temperature compensation circuitry included in the
MicroSafe™ design will compensate for this characteristic, however temperature extremes may still cause a shift in
the contrast. Display contrast can be adjusted by the user if necessary. However, changing the contrast requires that
the sensor housing be opened, thus declassif ication of the area is required.
To adjust the display contrast, remove the enclosure cover and use a jewelers screwdriver to turn the contrast adjust screw
located beneath the metallic face plate. The adjustment location is marked “CONTRAST”. See figure 6 for location.
3.11 T
ROUBLE
S
HOOTING
G
UIDE
SENSOR FAULTS
Open Heater
Verify resistance between black and white wires using ohm-meter with the sensor unplugged and at room tempera-
ture. Heater Film’s normal reading range should be 75-95 ohms. Failure would be an open circuit.
Open Sensor
Verify resistance between blue and yellow wires using ohm-meter with the sensor unplugged and at room tempera-
ture. Sensor Film’s normal reading range should be 5-100 k-ohms. For sensors with an “X” in the serial number, the
normal reading range should be 75 k-ohms to 2 meg-ohms. Failure would be open circuit.
SPAN CALIBRATION FAULTS – (Range, Stability, Zero)
To remove the span calibration fault, you must repeat the calibration process successfully.
Range Fault
1. Check Heater Voltage Setting (should be 5.25 V).
2. Use humidif ier with Distilled Water or inline humidifying tube.
3. Check validity of cal gas using H2S pull tube or other means (must be H2S in air background).
4. Check for obstructions through s/s sinter element (including being wet).
5. Check sensor lot # and report to Detcon.
Zero Fault
Must recover to <10% of range before calibration cycle is complete and returns to normal operation. Use bottled
air if necessary.
Detcon Model TP-524C Hydrogen Sulfide Sensor
PG.16
