| 摘要 |
PURPOSE:To provide a method and device for controlling change-over switch circuit by which the abnormality of a semiconductor switch or driving means can be detected quickly and, at the same time, the accuracy of the abnormality detecting level can be improved and the switching from one AC power source to another AC power source can be controlled easily and performed quickly. CONSTITUTION:A voltage detector 31 which has such a function that informs a discriminating means 32 of the presence/absence of the voltage level at the control terminal of a first semiconductor switch by using an electrically isolated signal by always comparing the voltage level with a reference voltage level which is the voltage level at the control terminal of the switch 6 when both the switch 6 and a first driving means 2 are normal and the discriminating means 32 which has such a function that gives a control signal to turn on a second semiconductor switch 7 and, at the same time, an abnormal state signal to a control circuit 1 when an abnormal state occurs by comparing the signal from the detector 31 with the state signal from the control circuit 1 are provided. |
