Compact low cost current sensor and current transformer core for circuit breakers having improved dynamic range

Abstract

A circuit breaker having a housing, a pair of separable contacts, a current sensor strap in electrical communication with the contacts, an operating mechanism for operating the contacts, an electronic trip unit in operable communication with the sensor strap and the mechanism, and a current transformer is disclosed. The current transformer has a mixed material magnetic core having a first layer of material having a relatively high magnetic permeability, and a second layer of material having a relatively low magnetic permeability abutting the first layer of material. The core has a profile with an opening therethrough for accepting the sensor strap. A signal generator is disposed proximate the core to provide an output signal representative of a magnetic flux associated with the sensor strap. The mixed material magnetic core exhibits a dynamic range greater than a dynamic range of a similar shaped magnetic core having only one material of the first layer of material and the second layer of material.