| 摘要 |
PROBLEM TO BE SOLVED: To continuously supply the power to a load even if an overload condition is temporarily generated while the power is supplied to the load from the commercial power supply. SOLUTION: If the overload condition is generated temporarily while the power is supplied to the load 4 from the commercial power supply 5, a detected voltage of a voltage detector 16 is lowered and thereby the voltage detector 16 outputs a power failure detecting signal 17, and an inverter control circuit 9A drives an inverter 1. In this timing, a power direction judging circuit 36 outputs a power direction judging signal indicating that the power direction is not the load regenerating direction to a switching control circuit 15A based on the detected signal from a voltage detector 23 and a current detector 48. Accordingly, the switching control circuit 15A maintains a semiconductor switch 7 of a connecting condition switching means 6 to the ON state. |
