Circuit protection apparatus

Abstract

A circuit protection apparatus 50, for fitting in an electrical circuit of a motor vehicle, includes an input terminal 54, an output terminal 56, and a breaker unit 60 electrically coupled between the input terminal and output terminals. The breaker unit is operable in a closed circuit state in which current is permitted to flow between the input terminal and output terminals and in an open circuit state in which current flow is prevented. A thermostat 70 generates a thermostat output signal 73 responsive to temperature, e.g. predetermined fault temperature, and the protection apparatus is configured to trigger the breaker unit into the open circuit state in response to the thermostat output signal. A method of isolating an electrical circuit of a motor vehicle using the circuit protection device is also provided. The breaker unit may be connected to the input and output terminals by first and second busbars and the thermostat, which may be a pyrofuse, may be coupled to one of the busbars. The protection apparatus may be connected between a battery 10 and a DC-DC converter 30 of a motor vehicle powertrain and may include a plurality of thermostats (70A-C, Fig.11), each capable of triggering the breaker unit.

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