Patent ID: 7002440

Claim:
A circuit breaker, comprising: 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 strap and the mechanism; and a current transformer comprising: 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; wherein the core has a profile with an opening therethrough for accepting the strap; and a signal generator disposed proximate the core to provide an output signal representative of a magnetic flux associated with the strap; wherein 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; wherein a root-mean-square current sensing accuracy of the mixed material magnetic core is equal to or greater than about 99.7% in response to a current in the current sensor strap being at about one times the current rating of the circuit breaker.