| 摘要 |
PROBLEM TO BE SOLVED: To provide a surge protective circuit capable of reducing a labor-hour of a restoring work required in the case in which an overcurrent flows with a simple constitution and a power source having the surge protective circuit. SOLUTION: A fuse F2 of the degree (e.g. 1 to 2A) that stops flow of an overcurrent to electronic equipment is connected to a current route between a filter circuit 20 circuit 20 disposed in the rear stage of the surge protective circuit 10 having a fuse F1 of the degree (e.g. 10A) that is not melted by a normal surge and connected to one input line L1 of input lines L1, L2 and a rectifying and smoothing circuit 30 disposed in the front stage of a switching power source circuit 40. The circuit 10 has varistors 12, 13 connected between the lines L1 and L2 and a gas arrester 15 connected between its common connecting point and a frame ground FG to be used. In this case, the total varistor voltage of both the varistors 12, 13 is set to an amplitude of the degree capable of absorbing a surge of a normal mode.
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