Abstract: Load power control circuits for single HID luminaires include both retrofit circuitry and “new manufacture” circuitry for connection to both controlled-voltage and controlled-current ballast circuits. A suitable such control circuit may be substituted for the capacitor in the capacitor-control type of ballast circuit. Control is effected by a microcontroller that controls selective switching by associated triacs of one or more capacitors connected in parallel across the ballast circuit. The reactor-control type of control circuit is interposed between the line supply and the ballast circuit, and may include parallel-connected pairs of opposed (reverse-coupled) silicon controlled rectifiers operating under the control of the microprocessor.

Abstract: The invention is a load voltage and power control and supply system for the supply of power to a load for which, over particular periods of time, usually on a daily basis, it is desired to reduce power. The invention has particular application to street lighting systems in which, for a period of several hours during the night (when traffic is minimal and many people are asleep), the luminaires of the lighting system can operate at reduced power. The power control system is able to act as a voltage stabilizer as well as a controlled power reduction system. The power control system may operate the bank of spaced luminaires from a single control location. Moderately reduced power (say a 30% reduction in power) supplied to luminaires does not noticeably diminish the adequacy of the illumination provided. Further, the power control system reduces power in stepwise decrements each of which reduces power by a small amount insufficient to diminish noticeably the ambient illumination.