Why do you need a shunt trip breaker?

A shunt trip breaker is installed like any other molded case breaker. The only difference is that it has an internal tripping coil that is usually connected to a C.T. The breaker is usually mounted in a MCC cabinet The top of the breaker is bolted to the MCC bus bars and the bottom of the breaker is connected to the load. The load conductors pass through the C.T.'s which induces a current into the circuit to trip the tripping coil in the breaker.