Estimated CCR output voltage for a series AGL circuit from load, circuit current, power factor and primary cable resistance.
A CCR holds the current constant and lets the voltage float to whatever the circuit needs. That voltage is the load's voltage plus the drop along the primary cable. This tool adds the two as phasors, so the cable's resistive drop and the load's reactive part are not simply summed, and checks the result against the cable's insulation rating and a chosen CCR.
Full-brightness power from the manufacturer's data sheet. For mixed fixtures, enter the total as quantity 1 with the combined watts.
Planning assumption. FAA AC 150/5345-47C sets minimum efficiencies at rated load, for example 80 % for 30/45 W and 65 W, 85 % for 100 W and 90 % for 200 W and above. A 30/45 W unit at the 80 % minimum raises the circuit load by about 12 % compared with 90 %. Replace with manufacturer data.
Power factor of the fixtures and transformers, not the cable. Planning assumption. FAA requires at least 0.95 for transformers at rated load; lightly loaded units are lower.
DC resistance at 20 °C. AWG values are nominal and mm² values are the IEC 60228 maximum. Verify against your cable data sheet.
Insulation rating from the cable data sheet. Series-circuit primary cable is commonly rated 5,000 V. Enter the value that applies to your cable.
FAA AC 150/5345-10H lists CCR sizes in kW, and IEC-style ratings are kVA. The circuit apparent power is compared with the number selected, which is the conservative reading. The rated output voltage is derived as rating ÷ rated current, for comparison only.
| Item | Value | Basis |
|---|---|---|
| Enter a valid load on the Calculate tab. | ||
Planning estimate at full-brightness current. Transformer efficiency and power factor are assumptions; replace them with manufacturer data.
Quick answers on estimating the CCR output voltage of a series AGL circuit.
It estimates the CCR output voltage for a series AGL circuit from the load, circuit current, power factor and primary cable resistance. A CCR holds the current constant and lets the voltage float to whatever the circuit needs, which is the load's voltage plus the drop along the primary cable. The tool also checks the result against the cable's insulation rating and a CCR you choose.
The cable's resistive drop and the load's reactive part are not simply summed. The cable drop is in phase with the current and adds to the real component only, and the load's reactive component is separate. The CCR output voltage is the square root of the sum of the squares of the real total and the reactive component.
The load real power is the number of fixtures times watts divided by transformer efficiency, or a value you enter directly. The apparent power is that divided by the power factor, and the reactive power is the square root of the apparent power squared minus the real power squared. Dividing the real and reactive powers by the series current gives the real and reactive voltage components.
The cable resistance is the resistance per km at 20 degrees C, corrected for temperature with 1 plus 0.00393 times the temperature minus 20, times the loop length divided by 1,000. The cable drop is the current times that resistance.
The cable headroom compares the result with the rated voltage you enter from the cable data sheet, and series-circuit primary cable is commonly rated 5,000 V. If you choose a CCR, its rated output voltage is derived as the rating divided by the rated current, for comparison only.
100 fixtures of 45 W at 90 percent efficiency give 5,000 W, and at a power factor of 0.95 the apparent power is 5,263 VA with 1,643 var reactive. At 6.6 A the real and reactive voltages are 757.6 V and 249.0 V. Over 4,000 m of #8 AWG at 20 degrees C the resistance is 8.244 ohms and the cable drop is 54.4 V, so the real total is 812.0 V. The CCR output voltage is 849 V and the apparent power is 5.61 kVA.
Calculator #13 gives about 855 V for the same circuit because it applies one power factor to the whole load including the cable. This tool treats the cable as purely resistive, which is the closer model. The result ignores cable reactance, which at 50 or 60 Hz is small compared with the resistance, so treat it as a planning estimate.
It is an estimate at full-brightness current. It does not model brightness steps, secondary cable, connectors, lamp-out or open-circuit voltage, and real output voltage also depends on CCR regulation. Transformer efficiency and power factor are assumptions, so replace them with manufacturer data. Final design shall be verified against manufacturer data and the standards and approval requirements that apply at the aerodrome.
Every step is shown so the result can be checked by hand.
From fixtures, the transformer-side real power is quantity × watts ÷ transformer efficiency. Or enter that real power directly.
The load's apparent and reactive power follow from its power factor. Dividing by the series current gives the voltage the load needs.
The cable is resistive, so its drop is in phase with the current and adds to the real component only.
This ignores cable reactance. At 50 or 60 Hz the reactance of a typical primary cable is small compared with its resistance, so treat the result as a planning estimate.
| Item | Value |
|---|---|
| 100 fixtures × 45 W at 90 % | P_load = 5,000 W |
| Power factor 0.95 | S = 5,263 VA, Q = 1,643 var |
| Circuit current | 6.6 A |
| V_real / V_react | 757.6 V / 249.0 V |
| #8 AWG, 4,000 m, 20 °C | R = 8.244 Ω, V_cable = 54.4 V |
| Real total | 812.0 V |
| CCR output voltage | 849 V |
| Apparent power | 5.61 kVA |
Calculator #13 gives about 855 V for the same circuit because it applies one power factor to the whole load including the cable. This tool treats the cable as purely resistive, which is the closer model.
It does not model brightness steps, secondary cable, connectors, lamp-out or open-circuit voltage, or the CCR's own regulation and losses, and it does not select the cable's insulation class. The cable rating comparison uses whatever rated voltage you enter.
ICAO Annex 14, Volume I, Chapter 8 (electrical systems) and Aerodrome Design Manual, Doc 9157, Part 5. IEC 61822 (constant current regulators). FAA AC 150/5340-30 (design and installation of airport visual aids), AC 150/5345-10 (constant current regulators) and AC 150/5345-7 (L-824 cable). Use the current edition of each.
Please read before relying on any content on this page or on any result or record produced by it.