Bidirectional Active Arc Suppressor for Switching of Direct Current Circuits
Original Publication Date: 1985-Jun-01
Included in the Prior Art Database: 2005-Feb-18
Any time electromechanical contacts such as used in relays and switches open, an electrical arc is drawn in the gap between the opening contacts. During the existence of the arc, damage is done to the involved contacts due to heating and metal migration. This problem is particularly acute when switching DC current because the current flow never passes through zero, extinguishing itself, as in AC current. There is a direct relationship between the rate of deterioration of the contacts and the magnitude of the voltage and current interrupted during switching. Because of this, most DC relay specifications are limited to 28 volts or less. While U.S. Patent 4,438,472 taught an effective means to shunt the energy away from electro-mechanical contacts, it would function only if the current was flowing in only one direction.