POWER-SUPPLY DEVICE

PROBLEM TO BE SOLVED: To provide a technique that detects not only a main DC voltage but also a sub-DC voltage, thereby contributing the protection of a main rectifier circuit and a sub-rectifier circuit.SOLUTION: A main power-supply circuit 119 drives a load 121. A main rectifier circuit 11 receives an AC voltage via a first switch 102 and supplies a main DC voltage Vdc1 to the main power-supply circuit 119. When an overcurrent flows through the main power-supply circuit 119 or the load 121 is an overload for the main power-supply circuit 119, the first switch 102 is cut off. Operating power is supplied to a control circuit 123 from a sub-power-supply circuit 117. A sub-rectifier circuit 12 receives the AC voltage so as to bypass the first switch 102 and supplies a sub-DC voltage Vdc2 to the sub-power-supply circuit 117. A DC voltage detection circuit 13 detects the main DC voltage Vdc1 and the sub-DC voltage Vdc2.