PROTECTION APPARATUS FOR CURRENT FLOWING CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide a protection apparatus for a current flowing circuit capable of appropriately switching a control circuit for controlling driving and stopping of a load into a sleep mode.SOLUTION: A protection apparatus comprises: a semiconductor relay circuit 11 for switching conduction to/from interruption of a current flowing circuit; a control circuit 12 for outputting a switching command signal to the semiconductor relay circuit 11 in response to an input signal; and a current sensor for detecting current flowing through the current flowing circuit. The control circuit 12 has a lower limit threshold determination section 27 for determining whether or not the level of the estimated temperature of an electric line has dropped below the lower limit threshold. The control circuit 12 comprises: a sleep timer control section 22 for measuring lapse time after off when the semiconductor relay circuit 11 determines that the load RL is in an off-state; and a sleep control section 23 for switching the control circuit 12 into the sleep mode when a predetermined time lapses at the sleep timer and the lower limit threshold determination section determines that the level of the estimated temperature of the electric line has dropped below the lower limit threshold.