| 摘要 |
A switching circuit for selectively coupling a load to an A.C. power source is disclosed. The switching circuit includes a diode-commutated master relay contact and a pilot relay contact coupled in series therewith. The master and pilot relay contacts are coupled between a load and the power source in such a manner that power is applied to the load whenever both the master and pilot relay contacts are closed. A timing and control circuit performs a switching operation to open the master relay contact during a first half-cycle of the A.C. waveform of the power source during which the commutating diode is forward-biased. The pilot relay contact changes state during the next half-cycle of the A.C. waveform and the master relay contact is reclosed during the following half-cycle of the A.C. waveform. |
