Patent ID: 8315028

Claim:
An overcurrent protection apparatus which is configured so that a plurality of load circuits each configured by a series connection of a semiconductor switch and a load are connected in parallel, and an electric power is supplied to the load circuits through a common power supply wiring, the overcurrent protection apparatus comprising: a first overcurrent detecting section that detects an overcurrent flowing through a power supply line on the basis of a degree of a counter electromotive force generated in the power supply wiring; a second overcurrent detecting section that is disposed in each of the load circuits and detects an overcurrent on the basis of a level of a current flowing through each of the load circuits; a delaying section that outputs a delay signal at a first delay time when the overcurrent is detected by only the second overcurrent detecting section, and outputs the delay signal at a second delay time which is shorter than the first delay time when the overcurrents are detected by both of the first overcurrent detecting section and the second overcurrent detecting section, wherein the delaying section comprises: a first filter circuit that outputs a filter output delay signal at the first delay time, and a second filter circuit outputs a filter output delay signal at the second delay time; and a controlling section that interrupts only the load circuit from which the overcurrent is detected by the second overcurrent detecting section in the plurality of load circuits.