| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power supply unit which, although compact and available at low cost, detects sticking of a relay and, even when a relay is actually stuck, secures sufficient safety. <P>SOLUTION: A power supply unit 1A comprises a main power supply 3 which receives electricity supply from an input power supply 2 via a pair of power supply lines L1 and L2, transfer contact type relays TRL1 and TRL2 which are disposed on the respective power supply lines, a controller 4, and a detection circuit 5A. A common contact c of each relay is connected to the input power supply, and each normally-closed contact a is connected to the main power supply. In each relay, the common contact and the normally-closed contact are connected, and the common contact and a normally-open contact are connected by a relay on/off signal sent from the controller, respectively. The detection circuit, which is connected between the normally-open contacts, outputs a detection signal on the basis of a voltage or a current fed from the input power supply. When no detection signal is output while a relay-off signal is being sent, the controller determines that the relay is stuck. <P>COPYRIGHT: (C)2013,JPO&INPIT |
