Power reduction control for inductive lighting installation

A control system for continuously, selectively reducing power consumption in an inductive lighting installation energized from an A.C. power source, the installation including at least one ga discharge lamp such as a fluorescent lamp energized through any of a plurality of different types of electromagnetic ballast having different harmonic distortion characteristics, the control system comprising:

• load energizing circuit means, including a signal-actuated normally-closed primary switch, for connecting an A.C. power source to the lighting installation;
• a signal-actuated, normally-open secondary switch connected in parallel with the lighting installation;
• actuation means for generating actuation signals and applying such actuation signals to the primary and secondary switches to actuate the primary switch open and to actuate the secondary switch closed in approximate time coincidence in each half-cycle of the A.C. power;
• zero-crossing detector means for generating zero-crossing signals at times TX indicative of zero-voltage transitions in the A.C. power;
• and program means, connected to the zero-crossing detector means and to the actuation means, programming the actuation means to generate
• (a) power reduction actuation signals at times T1 and T2 in each half-cycle of the A.C. power,
• (b) a first filter actuation signal at a time T3 prior to each zero-crossing time TX, and
• (c) a second filter actuation signal at a time T4 following each zero-crossing time TX;
• the program means including a plurality of programs each establishing a set of times T1, T2, T3 and T4 for several different power reduction levels for a particular type of ballast;
• and selection means for selecting a program to match the ballast type of the load.