Patent ID: 7218494

Claim:
An overload current protection device which cuts off the supply of current to a load when an overcurrent occurs, comprising: a switch for supplying or cutting off the current from a power source to the load; a current detector for detecting the current; and a control power source for applying power to each unit of the device, wherein the current detector is configured by a magnetic impedance element having a magnetic impedance effect, and magnetic flux generated by the current is detected using the magnetic impedance element, the overload current protection device further comprising: a current applying unit applying a high frequency current to the magnetic impedance element; a detection unit detecting an output of the magnetic impedance element; a correction unit correcting a detection result; a magnetic field applying unit applying a bias magnetic field to the magnetic impedance element; a magnetic field variable unit changing a median value of the bias magnetic field; and a control unit controlling a change of the median value, wherein the median value of the bias magnetic field is changed, the output of the magnetic impedance element is detected, and the output is corrected depending on the detection result.