Current limiting circuit breaker

Abstract

An iron wire resistor connected in shunt with the current limiting contacts of a circuit breaker. The current limiting contacts are in series with the main contacts of the breaker, and are separated by extremely high fault currents before the main contacts can respond. Opening of the limiting contacts shunts the high fault current through the resistor. The resistor has a positive temperature coefficient of resistance and heats rapidly to sharply reduce the magnitude of the high fault current. To prevent the connection between the resistor and a low resistance copper conductor from being destroyed by the high fault current an intermediate resistance value terminal of copper clad stainless steel is employed between the resistor and the copper conductor. The use of oppositely directed segments or a serpentine shape in the resistor substantially reduces inductance in the resistor circuit which would tend to impede transfer of the fault current into the resistor circuit and thus maintain the arc across the contacts. The wire is potted in a ceramic compound utilizing alumina or silica.

Dependencies are inferred from the claim text.