Energy management method and apparatus utilizing duty cycle reduction synchronized with the zero points of the applied voltage

Energy-management apparatus for use in a demand-limited alternating current circuit, which circuit includes a plurality of separate loads, including resistive loads, and means for automatically shedding certain of said loads when the actual demand of said circuit exceeds said demand limit, said apparatus including:

• (a) means for establishing a demand limit for said circuit;
• (b) means for sensing the actual demand of those loads in said circuit which are in operation, including separately sensing the demand imposed by at least certain of the operative resistive loads in said circuit;
• and
• (c) means for reducing the duty cycle of the applied power furnished to at least certain ones of said operative resistive loads by switching said loads "off" and "on" synchronously with the zero points of the applied voltage, to effect an overall reduction in the actual demand of said circuit when the failure to make such reduction would otherwise cause certain of said operating loads to be completely shed.