| 摘要 |
PURPOSE: To improve reliability in power feeding to a load without interruption in power, by detecting misfiring at a semiconductor switch during power feeding from a commercial power supply, and feeding the power continuously from the commercial power supply through a bypass contact. CONSTITUTION: When a semiconductor switch 4 has misfiring during the power feeding from a commercial power supply 2A, the misfiring state is detected by a semiconductor switch misfiring detection means 7 and a bypass contactor 8 is closed to continue the power feeding from the commercial power supply 2A to a load 5 through the bypass contactor 8. An output voltage to the load 5 is monitored through a voltage relay by the semiconductor switch misfiring detection mean 7. The three-phase AC output voltage is monitored by a voltage relay 71 and the logical sum of the output contact of the voltage relay 71 is used to close the bypass contactor 8 through an interlock circuit. |
