US Patent 7221106 Cordset based appliance controller

An apparatus and method for distributed control of an electrical appliance having a plug and a load and two power carrying conductors connecting the plug to the load, comprising locating power control elements completely within the plug, connecting interface elements to the two power carrying conductors, which interface elements are not within the plug, and transmitting status information from the interface elements to the power control elements by imposition of electrical signals onto the two power carrying conductors, wherein the electrical signals comprise an adjustable duration deadzone at a zero crossing of a sinusoidal excitation.