What Is a Shunt Circuit Breaker?

Circuit Breakers

• Circuit breakers operate by detecting a fault, or short circuit. Contacts contained in the breaker then separate via a spring mechanism or compressed air. Opening the contacts causes the circuit breaker to trip, or power to the circuit to be interrupted or diverted.

Magnetic Coil

• Shunts in a shunt-trip style breaker operate via a magnetic coil. This coil energizes externally via an electrical charge, which generates a magnetic field. The magnetic field enables contacts to separate, effectively diverting power and tripping the breaker.

Crowbar Circuit

• Shunts used in circuit breakers may take the form of crowbar circuits. Crowbar circuits prevent over-voltage from damaging circuits connected to a power supply by placing a path of low electrical resistance, or a short circuit, across a voltage source. Once the crowbar circuit activates, it relies on the current-limiting circuitry of the power supply. Upon failure of this circuitry, the crowbar circuit will trip the circuit breaker to interrupt power.