| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a power backup device, capable of conducing switching to another power supply instantaneously, automatically, and economically without stopping load, if a failure occurs in a power supply during supply. SOLUTION: Power supply to the load 40 from one of two power supplies of lines 1a and 2a is conducted via the contact 24a of a relay 24. A frequency synchronization and voltage difference detecting circuit 11 and a voltage failure rapid detecting circuit 12 monitors the presence or absence of failure in the two power supplies. A mode switch 17 conducts selection of the power supply and an operating mode. From the detected results, according to failure occurrence, SCRs 31 and 32 and the relay 24 are controlled, based on the operating conditions of the first and second relays. Automatic switching is made to a power supply in normal operation on backup side.</p> |
