Hybrid power switching device

摘要

A hybrid power switching device for eliminating mechanical relay arcing. The device reduces mechanical relay contact damage due to arcing and substantially reduces power dissipation by placing a solid state relay in parallel with a mechanical relay. The solid state relay is preferably a semiconductor triac optically coupled to a light emitting diode. The device takes advantage of the inherent lag time (operating time) when a mechanical relay contact switch closes. The device uses only analog components and controls the triac by means of a Schmitt trigger pulse stretcher. The advantages to the present Schmitt trigger include discrete turn off and a narrow hysteresis. A low level control voltage signal operates the mechanical relay and the Schmitt trigger, or optionally a high level control voltage signal in conjunction with a signal inverter.