The CCR fault indication
When a CCR cannot do its job it tells you in a few ways. Read the indication first, then use it to decide where to look.
1Read before you touch
Note the indicator lamps, the display code and the state of the output before resetting or changing anything. This is the only record of what the CCR saw at the moment of the fault.
2Match the indication to the zone
No output points to the supply, breaker or a trip. An open-circuit indication points to a break in the series loop. A low-insulation or earth-fault indication points to the circuit cable, joint, connector or transformer, not usually the CCR itself.
3Then isolate safely
Before testing the circuit, isolate and lock out. Work from the CCR outward, section by section (half-split the loop at accessible points), using the fault flowchart and the insulation test, rather than guessing. Discharge the cable after any insulation test before touching the conductors.
| Element | Detail |
|---|---|
| No output | Check supply, input breaker, trip indication, local or remote state |
| Open-circuit indication | Look for a break in the loop: connector, cut cable, open primary winding of an isolating transformer. A failed lamp alone does not open the loop when an isolating transformer is used |
| Overload, overcurrent or over-temperature | Check circuit load against the CCR rating, cooling and ventilation |
| Low insulation or earth fault | Test the circuit insulation and locate the leakage |
| Supply alarm | Check incoming supply and surge protection |
| Always | Record the indication before resetting |
| Reference | IEC 61822 · FAA AC 150/5345-10 · FAA AC 150/5340-26 |
Frequently Asked Questions
Q1What should I check first when a CCR shows a fault?
Record the indication, then check whether the supply is present and whether the CCR has tripped. Do this before resetting anything.
Q2Is every CCR fault a CCR fault?
No. Open-circuit and earth-fault indications usually mean a fault in the series circuit that the CCR has detected, not a fault in the CCR itself.
Q3Can I just reset and see?
Reset only after finding the cause. Repeated resets on a hard fault can damage equipment and mask the real problem.
Q4Where does the CCR send fault information?
To its display and indicators, and through relay outputs or a communications link to the ALCMS where fitted.
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