Shunt Trips – Shunt Trip Circuit Breakers

A shunt trip is an optional accessory device that electricians and/or manufacturers install to a circuit breaker. This is known as a shunt trip circuit breaker. Some circuit breakers allow shunt trip kits to be installable in the field. Others require factory installation when ordering the circuit breaker. You can check your specific type of circuit breaker for the ac and dc shunt trip voltage ratings and how to install these shunt trips.


So How Does a Shunt Trip Breaker Work Exactly?

Well, we know that circuit breakers trip automatically when there’s an electrical surge (current exceeds the specified limit). This is still true for circuit breakers with a shunt trip. The first two contacts of a shunt trip breaker are connected by a metallic strip on a switch and an electromagnet placed underneath the switch. Electricity flows through the metallic strip under normal conditions. But when a surge occurs, the excess power charges the electromagnet which trips the switch and cuts the connection and power. In addition to this normal tripping mechanism, a shunt trip breaker has an external power source that powers it. This external system wires to the electromagnet in the circuit breaker, and this connection can send an electrical signal that can also charge the electromagnet and trip the switch.


Why are Shunt Trip Breakers Important?

Shunt trip breakers essentially provide an off switch remotely or a direct link to a system outside the main breaker. Remote manual switches allow for human control while direct link automatically shuts off the breaker.

An example of a direct link is safety systems such as smoke detectors and fire emergency button/switch are some of examples of an external source. For instance, when smoke triggers a smoke detector, the breaker trips automatically. This cuts the power to electrical equipment at the same time the smoke detector triggers the sprinkler. The immediate break in power minimizes electrical damage, and prevents short circuits and electrocution risk . On the other hand, shunt trip breakers can be remotely shut off, for instance when there is fire damage- someone can turn off power to another building via a remote manual switch. Shunt trip breakers are important safety features in preventing damage to electrical equipment as well as injury to people.

Overall, shunt trip breakers add additional safety features to breakers and ultimately play an important role in the electrical system. They shut off electrical power during emergencies and serve to prevent damage to equipment and injury to people.