Electronic control system for operating a street lamp

摘要

An electronic control system for operating lighting is rated and operable from normal AC mains supply voltages. A street light controller is adapted to activate a luminaire when ambient light levels are considered too dark and, conversely, when ambient light levels are sufficient, the luminaire is turned off.

主权项

1. An electronic control system for operating a luminaire for a street lamp rated and operable from normal AC mains supply voltages, said electronic control system including;
a comparator; a first AC input signal to said comparator wherein the first AC input signal provides a reference current, and a second AC input signal to said comparator derivable from a photo detector arrangement, wherein the second AC input signal provides a measured current, such that the comparator establishes an output DC current of magnitude and direction directly proportional to the instantaneous difference in magnitude between the first AC input signal and the second AC input signal to the comparator; a capacitor in communication with said output DC current established from the comparator such that at a threshold voltage level of the capacitor a responsive signal is made available; a TRIAC connected to the AC mains supply to control and conduct power to the luminaire for illumination of the lamp wherein the TRIAC is in communication with the responsive signal such that once the responsive signal has been made available the TRIAC conducts AC mains supply through to the luminaire; a trigger circuit including a bi-polar junction transistor wherein the bi-polar junction transistor switches on for a period during a zero crossing interval of the AC mains supply wherein the zero crossing interval is detected by a sensor in communication with the gate of the TRIAC, such that the turning ON/OFF of the bi-polar transistor triggers a pulsed signal to the gate of the TRIAC so that the pulsed signal is adapted to drive the gate of the TRIAC during zero crossing intervals to maintain conduction of the TRIAC for a complete cycle of the AC mains supply.