The CCR power output
The CCR sets the current. The load sets the voltage. Together they decide how much power the CCR delivers and whether the rating is large enough.
1Current is fixed, voltage follows
The CCR holds the output current at the selected step. The output voltage is whatever is needed to drive that current through the circuit, so it rises with more lights or longer cable.
2Power is current times voltage
The output kVA is the output current multiplied by the output voltage. The circuit load is the sum of every lamp load, the isolating transformer losses and the cable losses (I²R). CCRs are rated in kW or kVA depending on the specification. The rating must cover that total, with allowance for growth.
3Stay inside the limits
Too large a load pushes the CCR to its limit. A load that is too small can also be a problem on some models, which need a minimum load to regulate properly. Both limits come from the manufacturer.
| Element | Detail |
|---|---|
| Output current | Set by the brightness step, with 6.6 A at the highest step on typical circuits (some circuits use 20 A); the same current through every light primary |
| Output voltage | Depends on circuit impedance: lights, transformers, cable |
| Output power | Current times voltage |
| CCR rating | kW or kVA; must cover the calculated circuit load plus growth |
| Maximum load | Do not exceed the stated rating |
| Minimum load | Some models need a minimum connected load; check the manual |
| Reference | IEC 61822 · FAA AC 150/5345-10 · ICAO Doc 9157 Pt 5 |
Frequently Asked Questions
Q1Does the CCR output voltage stay constant?
No. The current is held constant and the voltage rises or falls with the load on the circuit.
Q2How do I check the CCR is big enough?
Add up the lamp loads, the isolating transformer losses and the cable losses for the circuit, then choose a CCR whose rated output covers that with a margin for future lights. Stay inside the manufacturer minimum and maximum loading.
Q3What if the load is much smaller than the rating?
Some CCR designs need a minimum load to regulate accurately. Check the manufacturer minimum-load guidance.
Q4Why does adding lights raise the voltage?
Each light adds load in the series loop. To keep the same current through more load, the CCR must drive a higher voltage.
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