Patent ID: 6300878
Filing Date: 2001-10-09
Classification: H05B,Y02B

Abstract:
An airport runway lighting system comprising:a series of lights used along the runway;an AC source that provides power to the series of lights; anda constant current regulator that receives an AC input current from the source at provides a constant AC current to series of lights, the regulator comprising:a first electronically controllable switch;a second electronically controllable switch;a second electronically controllable switch;a third electronically controllable switch;a fourth electronically controllable switch;a transformer coupled to the switches such that:an output of the first switch is electrically connected to an input of the second switch and one input of the transformer primary winding, andan output of the third switch is electrically connected to an input of the fourth switch and another input of the transformer primary winding; anda controller connected to the switches, the controller programmed to:provide trigger signals to each of the switches, andadjust a duty cycle of the trigger signals based on a comparison between an actual current value and a reference current value to provide a constant AC current to the lights;wherein the switches are arranged such that the AC input current is supplied to the transformer primary winding when the trigger signal to the first switch is on and the trigger signal to the third switch is on.