Analysis of force characteristic of short-circuit release in low voltage circuit breaker

A short-circuit tripping device is an integral part of a miniature low-voltage circuit breaker. As far as its design is concerned, the release mechanism comprises a metal case with a moving armature and a compression spring; the armature is further surrounded with winding (coil) made of copper wire. Short-circuit current flowing through the protected circuit brings the release armature in motion and the force produced acts on the mechanism lock to arm the breaker. This paper will present application of electromagnetic FEM analysis to calculate the static and dynamic characteristics of force acting in short-circuit release of a circuit breaker. The both analysis are compared to the real measurement of armature moving by the help of high-speed camera.