nvent 910 Series Installation, Operating And Maintenance Instructions page 59

Cause of Alarm:
• Excessive current caused by in-rush current
• C.B. CURRENT RATING setting too low for normal heater current draw or not matched to
actual circuit breaker size
8.3.16 SWITCH LIMITING
This alarm indicates that the controller is limiting the average current that is applied to the
trace circuit based on the SWITCH RATING setting to protect the solid state relay from
excess current.
Cause of Alarm
• Excessive current caused by in-rush current
• Excessive ambient temperature
8.3.17 HIGH RESISTANCE
This alarm indicates that the heating cable resistance has deviated from the NOMINAL
RESISTANCE setting by more than the HIGH RESISTANCE ALARM setting.
Cause of Alarm
• Alarm setting too close to actual operating resistance
• NOMINAL RESISTANCE not set properly
• Open connection—wiring problem
• Damaged cable
8.3.18 LOW RESISTANCE
This alarm indicates that the heating cable resistance has deviated from the NOMINAL
RESISTANCE setting by more than the LOW RESISTANCE ALARM setting.
Cause of Alarm
• Alarm setting too close to actual operating resistance
• NOMINAL RESISTANCE not set properly
• Partial short—wiring problem
• Damaged cable
8.3.19 EEROM DATA FAILURE
This alarm indicates that the controller has detected a failure in its nonvolatile memory (this is
where all of the controller's configuration and calibration settings are stored). This indicates an
internal problem and the HTC should be replaced and returned to the factory for repair.
Cause of Alarm:
• The HTC cannot bypass the failed area of its memory and has loaded factory defaults into
this failed area.
8.3.20 CONTACTOR COUNT
This alarm indicates that the number of off-to-on transitions of a contactor has exceeded the
CONTACTOR COUNT ALARM setting and the contactor should be replaced.
Cause of Alarm
• Contactor has been controlling the trace circuit for a long time
• Some configuration parameter (i.e. DEADBAND, AUTO CYCLE INTERVAL, load shedding etc.)
is causing the contactor to toggle more than usual.
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