| 摘要 |
PROBLEM TO BE SOLVED: To make the capacity of a main switch in a power supply circuit as small as possible. SOLUTION: A power capacitor C1 which is parallel to a load 1 is connected with a main switch SW1 connected with a battery BT via the contact of a precharge relay RY1, and the contact point of a fail safe relay RY2 is arranged in parallel to a precharge resistor R1. A control system power supply 2 in which a power supply voltage signal is inputted by the operation of the relay RY1, a reset circuit 3 which outputs a delay operation signal of a specified time, and a CPU 4 wherein reset is canceled by the reset circuit 3 are installed. When the switch is turned on, the relay RY2 is excited by the CPU 4 in the state that the relay RY1 is excited, charge is performed via a resistor, and the switch can be prevented. When the switch is turned off, the relay RY2 is put in the state of nonexcitation prior to the relay RY1 in the state of excitation, discharge is performed via the resistor, and welding of the relay contact can be prevented. |
