| 摘要 |
A power control and diagnostic arrangement illustratively embodied in an electric range having multiple surface heating units which are selectively coupled to an AC power supply by commutated relay switching circuitry. The commutated relay switching circuitry includes two switching networks. Each network includes a diode commutated master relay serially connected to a pair of pilot relays. Each pilot relay is serially connected to one of the surface units. Timing and control circuitry periodically interrupts operation of the power circuit in a normal mode to operate in a diagnostic mode. In the diagnostic mode the relays are switched in a predetermined sequence to test for a short circuit failure of the master relays or commutated diodes, an open circuit failure of the diodes, an open circuit failure of the master relays, a short circuit failure of the pilot relays and an open circuit failure of any individual pilot relay. Upon detection of a failure of a master relay or diode or a short circuit failure of a pilot relay, the master relay and pilot relays for the switching network containing a failed component are de-energized. A user discernible signal is generated informing the user that a failure has been detected.
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