Detcon FP-524D INSTRUCTION MANUAL - Manual (Page 29)

Model FP-524D
FP-524D Instruction Manual Rev. 1.4 Page 25 of 39
Hold the magnet over PGM1 or PGM2 for 3 seconds to accept the new value (until the display starts to scroll
“Saved”). Move to another menu item by executing a momentary hold, or, return to Normal Operation via
automatic timeout of about 15 seconds (the display will scroll “Fault Settings” 4 times and then return to
Normal Operation).
3.6 Program Features
Detcon FP-524D combustible gas sensors incorporate a comprehensive set of diagnostic features to achieve
Fail-Safe Operation. These Operational features and Failsafe Diagnostic features are detailed below.
3.6.1 Operational Features
Over-Range
When gas greater than the full-scale range is detected, the sensor display will continuously flash the full-scale
reading of 100. This designates an over-range condition. The 4-20mA signal will report a 22mA output
during this time.
In-Calibration Status
When the sensor is engaged in AutoZero or AutoSpan calibration, the 4-20mA output signal is taken to
2.0mA. This alerts the user that the sensor is not in an active measurement mode. This feature also allows the
user to log the AutoZero and AutoSpan events via their master control system.
Sensor Life
Sensor Life is calculated after each AutoSpan calibration and is reported as an indicator of remaining service
life. It is reported in the “View Sensor Status” menu. Sensor Life is reported on a scale of 0-100%. When
Sensor Life falls below 25%, the sensor cell should be replaced within a reasonable maintenance schedule.
Last AutoSpan Date
This reports the number of days that have elapsed since the last successful AutoSpan. This is reported in the
View Sensor Status menu. After 180 days, an AutoSpan Fault will be declared.
3.6.2 Fault Diagnostic/Failsafe Features
Fail-Safe/Fault Supervision
Model FP-524D MicroSafe™ sensors are designed for Fail-Safe operation. If any of the diagnostic faults
listed below are active, the sensor display will scroll the message “Fault Detected” every 60 seconds during
normal operation. At any time during “Fault Detected” mode, holding the programming magnet over PGM1
or PGM2 for 1 second will display the active fault(s). All active faults are reported sequentially.
Most fault conditions result in failed operation of the sensor. In these cases the 4-20mA signal is dropped to
the universal fault level of 0mA. These include the AutoZero and AutoSpan Calibration faults, Sensor Faults,
Processor Fault, Memory Fault, Loop Fault, and Input Voltage Fault. (The 0mA fault level is not employed
for a Temperature Fault, or during Calibration.)
NOTE: Refer to the Troubleshooting Guide, Section 5, for guidance on fault conditions.