The Shunt Trip (Release) Coil function is to allow mechanical tripping/opening of a Molded Case Circuit Breaker by a remote device other than by the overload & short-circuit mechanism already built into the breaker. (Usually thermally activated)
In many cases the Shunt Trip function is used for Ground Fault protection of the equipment being supplied by the breaker however it can be used to trip/open the breaker for any reason. (Equipment Protection Interlock Permissives, Equipment Safety Permissives, Low Voltage & Over Voltage Protection, Buss Transfer Interlock, and many other reasons as dictated by the application needs.)

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  F360 Shunt Trip Electrical Accessory