Light Emitting Diode Taxiway Lighting Effects on Constant Current Regulator Stability

This study was conducted to determine how light emitting diode (LED) taxiway edge lights affect the operation of Constant Current Regulators (CCR). Some CCRs turn off due to overvoltage or overcurrent because of LED taxiway edge lights.

A test bed was developed to measure and record the voltage and current supplied to an LED taxiway edge fixture as power was applied. The test bed setup consisted of an LED taxiway edge fixture, circuit current control subsystem for constant current to the taxiway edge fixture, and a data acquisition subsystem, which collected the data for analysis. Five types of LED taxiway edge fixtures were used for the testing.

The baseline incandescent taxiway edge fixture had a smooth power curve. Two of the five LED taxiway edge light fixtures showed significant peak power volt ampere (VA) loading after power-up compared to the loading during normal operation. The highest peak power VA was 163% of the nominal VA required.

Based on the results of this study, the following are recommendations for future operation of LED taxiway edge lighting fixtures. 

• The peak power VA required by an LED taxiway edge lighting fixture should not exceed the nominal operating power VA by more than 10% for the fixture. When the peak load is limited to 10%, the CCR will have enough reserve capacity to support the load and should easily adjust so that it will not trip off due to an overvoltage condition. 
• The LED taxiway edge light fixture should not drop the power VA required at a given step by more than 10%. When the power VA load suddenly drops, the CCR can trip off due to overcurrent. By limiting the power VA drop to 10%, the overcurrent protection function of the CCR should easily adjust so that it will not trip off due to an overcurrent condition.