Electrical current sensing and monitoring methods include connecting a compensation circuit across a conductor having a non-linear resistance such as a fuse element. The compensation circuit injects a current or voltage to the conductor that allows the resistance of the conductor to be determined. The current flowing in the conductor can be calculated based on a sensed voltage across the conductor once the resistance of the conductor has been determined.

Provided is a semiconductor DC breaker which has redundancy so as to be able to interrupt a current even if a semiconductor switching element for cutting off a current when an abnormal current is detected has failed. This semiconductor DC breaker 1 having a semiconductor switching element 21 that interrupts a main current when an abnormal current is detected comprises: a fuse 25 connected to the semiconductor switching element 21 in series; an abnormal current detection unit 11 that detects an abnormal current; and a gate drive unit 12 that turns off the semiconductor switching element 21 when the abnormal current is detected by the abnormal current detection unit 11. The magnitude of the abnormal current at which the semiconductor switching element 21 is to be turned off is set to be smaller than magnitude of a fusing current of the fuse 25.

A circuit protection device may include a current sensor and a pyrotechnic fuse connected to the current sensor, wherein the pyrotechnic fuse includes a housing and a busbar extending through the housing, and wherein the busbar is positioned between a first chamber and a second chamber. The circuit protection device may further include a piston within the first chamber, wherein the piston is operable to receive a force from a squib, and wherein in response to a signal from the current sensor, the force from the squib causes the piston to create an opening in the busbar.