Light Emitting Diode Taxiway Edge Lights Emissions Evaluation

摘要

This study was conducted to evaluate taxiway edge fixtures using light emitting diode (LED) technology to determine (1) if electrical emission levels from these fixtures are sufficient to cause interference to airfield circuits and warrant further investigation and (2) if there is a need to change the certification requirements for these electrical emissions. Five LED fixtures from different manufacturers were tested. The airfield lighting test bed located at the William J. Hughes Technical Center was used to measure the emissions of the fixtures. Electrical emissions occur in two forms, harmonic and nonharmonic. Harmonics are a distortion of the normal electrical frequencies emitted by the LED fixtures, which can cause problems with other equipment. Multiple electronic devices on a circuit, all emitting similar harmonics, can be additive and disruptive to the power distribution network. Harmonic emissions can cause voltage variations and overheating of the airfield circuit wiring. Nonharmonic emissions are a result of the circuitry in the power supply, which causes frequencies that are multiples of the power supply switching frequency. This can cause interference on the electrical circuit. The current certification requirements contain procedures to test for emissions, with the lowest frequency being 150 Hz. The data from this study showed that four out of five fixtures had significant emissions that could possibly cause interference. These emissions were at a frequency as low as 12 kHz, which is much lower than the current certification requirements of 150 Hz, and warrants a change in the certification requirements.