Dual Zone Digital Location Control Unit Installation and Operation Manual
24
Relay fault
A relay fault is indicated when an alarm condition exists and the alarm relay state
doesn’t change.
ZONE 1: RLY FLT
ZONE 2: OK
Caution:
A relay fault cannot be repaired. In the event of a relay fault, a
replacement control unit will be required.
Interference fault
EMC interference can cause problems with the monitoring of the cable –
providing false values, intermittent faults/alarms, etc.
If the control unit registers a fluctuation in the monitored values, an interference
fault is indicated by activating the zone fault fault LEDs and fault outputs.
ZONE 1: I/F FAULT
ZONE 2: OK
If an interference fault occurs then the source of the interference must be
investigated. Once the cause of the interference is discovered, then the issue
can generally be resolved by moving the cable away from the source of the
interference.
Note:
If interference is likely to be an issue then it may be necessary to consider
a stainless steel braided variant of the sensor cable and connect the outer braid
to earth.
Ground fault
The control unit monitors for ground faults caused by a section of the sensor
cable or interposing cable that has been damaged and the cable core is in
contact with bare metal (that is, a fixing point, etc.)
Should a ground fault occur, the control unit activates the relevant fault
indications and outputs and displays the following message.
ZONE 1: GND FLT
ZONE 2: OK
The most likely cause of a ground fault is a damaged cable, therefore an
inspection of the sensor cable and any interposing cable attached to the zone is
necessary (checking for any damage to the cable outer sheath, any contact with
sharp metal edges, etc.)
