| 摘要 |
PURPOSE:To detect a failure in the so-called by-pass switch which is used in an inverter device and to make sure of the soundness of the operation of the switch during operation of the inverter device. CONSTITUTION:An inverter 1 supplies power to the load not shown in the figure through a feeder 4. The feeder 4 is supplied with power from commercial power lines 10 through a thyristor switch 5 (by-pass switch). With a phase difference between a voltage of a commercial power supply and inverter 1 being controlled by a synchronous controlling circuit 12, a voltage is supplied across main circuit electrodes 9 of each of thyristors 6a-8b and then the voltage is detected by a transformer 21. And, the output of a comparator 24 is indicated by a frequency indicator 25 to know whether there is an abnormality in each thyristor. While switching the single-pole switches 6-8 or thyristors 6a-8b individually for preventing a runaround circuit from being generated, the switching operation of the single-pole switches 6-8 and thyristors 6a-8b is confirmed by the indication of the frequency indicator 25. |
