Airport and AGL Engineering Calculators

AGL series circuit load and constant current regulator sizing, with cable resistance, loss and insulation test calculators for airfield circuits.

Airfield ground lighting runs on series circuits. A constant current regulator (CCR) drives the same current through isolating transformers and lamps along a loop of cable, commonly 6.6 A at full brightness. The AGL calculator adds the lamp load, transformer losses and cable loss to give the circuit load, the output voltage and the smallest standard CCR. Two companions work the same loop from the other direction and for the supply side: the maximum fittings calculator tells you how many fittings a given CCR can carry, and the CCR input energy calculator turns the output load into input kVA and annual running cost. The isolating transformer calculator works out the lamp current, lamp voltage, primary voltage drop and transformer loading at the circuit current you enter, so check one brightness step at a time using the lamp power from the fitting data sheet at that step. The cable and insulation calculators listed below are general-purpose tools that apply to the cable loop.

Where to start

1. AGL Series Circuit Load and CCR Size: Circuit load, output voltage and the smallest standard CCR.
2. Cable Resistance: Loop resistance from length, cross-section and material.
3. Cable Power Loss (I²R): I²R heat dissipated in the cable run.
4. Polarisation Index and Dielectric Absorption Ratio: Polarisation index and dielectric absorption ratio from timed insulation resistance readings.

All 10 calculators in this category

Airport and AGL

• AGL Series Circuit Load and CCR Size: Output load, loop voltage and the smallest standard constant current regulator for a series lighting circuit. Open in Elecmetric
• AGL Maximum Fittings on a CCR: Largest number of fittings a constant current regulator of a given kW rating can carry on a series circuit, after cable loss. Open in Elecmetric
• AGL Isolating Transformer Current and Loading: Secondary lamp current, lamp voltage, primary voltage drop and loading of a series isolating transformer at a given circuit current. Open in Elecmetric
• AGL CCR Input Power and Annual Energy: Input kW, kVA and kvar of a constant current regulator from its output load, with annual energy and running cost. Open in Elecmetric
• AGL Brightness Step Current and Circuit Load: Circuit current, lamp load, cable loss, CCR output voltage and load at one brightness step of a 6.6 A series lighting circuit. Open in Elecmetric
• AGL Lamp Life at a Different Circuit Current: Fits a power law to two lamp life readings from a data sheet and gives the life at another circuit current, with the replacements a circuit needs each year. Open in Elecmetric
• AGL Series Cable Loop Resistance and Loss: Loop resistance, voltage drop and heat loss of a series lighting circuit cable from its length, size, material and temperature. Open in Elecmetric
• AGL Series Cable Size for a Loss Limit: Smallest conductor size for a series lighting loop so that the cable loss stays within a chosen share of the lamp load. Open in Elecmetric
• AGL Circuit Load with Failed Lamps: How the load and the CCR output voltage of a series lighting circuit change when some lamps have failed open and their isolating transformers are left with open secondaries. Open in Elecmetric
• AGL Light Intensity at Distance (Allard's Law): Illuminance at the pilot's eye from a light of given intensity, at a distance, through fog or haze described by the meteorological optical range (MOR). Open in Elecmetric

Also useful here

These sit in other categories but apply to the same work.

• Cable Resistance: Conductor resistance from length, cross-section and material. Open in Elecmetric
• Cable Power Loss (I²R): Heat dissipated in a cable run and the share of the load power it wastes. Open in Elecmetric
• Insulation Resistance Temperature Correction: Insulation resistance corrected to a 40 °C reference using the halving-per-10 °C rule of thumb. Open in Elecmetric
• Polarisation Index and Dielectric Absorption Ratio: PI and DAR from timed insulation resistance readings. Open in Elecmetric

What these calculators do not cover

Cross-check: all 14 calculators listed here are compared with 303 reference calculations written separately from the engine. This confirms the arithmetic and selection rules. It does not confirm that a standard table or convention matches your standard or manufacturer data.

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