The CCR failure modes
A CCR can fail inside the unit, but many apparent CCR faults begin on the supply or in the series circuit. Knowing the pattern saves time.
1Supply side
Loss of supply, a tripped breaker, a missing phase or a supply outside tolerance all stop or disturb the output. These are the first things to rule out, because they are quick to check.
2Inside the CCR
Control board faults, damage to the power stage (including surge damage), a failed contactor, blocked filters or cooling failure and ageing components can stop regulation or cause a trip. Heat and dust are common underlying causes.
3The circuit it feeds
An open circuit or an earth fault in the series loop is often reported by the CCR but caused outside it. Water ingress at connectors and joints, damaged cable and failed isolating transformers are common causes. Isolate the CCR and check the circuit with continuity and insulation tests before replacing the CCR.
| Element | Detail |
|---|---|
| Loss of supply | No output; check breaker, supply and phases |
| Supply out of range | Warning or trip; check supply voltage |
| Control board fault | Wrong step, no response or unexpected trip |
| Power stage or contactor fault | Output unstable or absent |
| Overheating | Warning then trip; check fans, filters, ventilation |
| Open or earth fault in circuit | Trip or alarm; test the circuit, not just the CCR |
| Reference | ICAO Annex 14 Vol I Ch 10 · FAA AC 150/5340-26 · IEC 61822 · FAA AC 150/5345-10 |
Frequently Asked Questions
Q1What fails most often on a CCR?
It depends on the model and environment. Heat, dust and ageing components are common underlying causes, and supply problems are common triggers.
Q2How do I tell a CCR fault from a circuit fault?
Isolate the CCR and test the circuit. If the circuit tests clean and the CCR still misbehaves into a known good load, the CCR is the suspect.
Q3Why does cooling matter?
Heat shortens component life and can trigger over-temperature trips. Keep fans, filters and ventilation clean and working.
Q4Does a single CCR failure put the whole airfield in the dark?
Only the circuits it feeds are affected. A standby CCR, and interleaving lamps across two circuits where the design allows, reduces the impact.
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