| 摘要 |
PURPOSE:To switch both a commercial power source and a generator power source without momentary power interruption by providing a FF circuit for turning ON one of first and second semiconductor switching elements provided between a load and a power source and turning OFF the other. CONSTITUTION:The power of a generator 1 is monitored, detected by a generator power detector 16 by a generator power detector 16 on the basis of a voltage, a current from a generator power detecting transformer CT, and transmitted to a switching load selecting calculator 21. The calculator 21 selects an optimum switching load L1 on the basis of various information, a selected signal is fed to a zero-cross switching instruction unit 29 through an AND circuit 23 and an OR circuit 27, and a command for switching the load L1 from a bus A to a bus B is fed to a FF circuit 32. A driver 42 switches a FF circuit 41 to a reset state to input a low gate signal to a switching element SSR1 and a high gate signal to a switching element SSR2. When the element SSR1 is turned OFF, the element SSR2 is simultaneously turned OFF to switch the load L1. |
