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Load control device having stuck relay detection

  • US 10,325,740 B2
  • Filed: 02/15/2017
  • Issued: 06/18/2019
  • Est. Priority Date: 03/31/2015
  • Status: Active Grant
First Claim
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1. A load control device for controlling power delivered from an AC power source to an electrical device, the load control device comprising:

  • a relay adapted to be electrically coupled between the AC power source and the electrical device, the relay being configured to receive a hot voltage from the AC power source and generate a switched-hot voltage for controlling the power delivered to the electrical device;

    a detect circuit electrically coupled to the relay to receive the switched-hot voltage and configured to generate a detect signal indicating a magnitude of the switched-hot voltage;

    a control circuit configured to generate a drive signal for attempting to open and close the relay, configured to monitor the detect signal, and configured to determine whether the relay is open or closed based on the detect signal;

    wherein, in response to determining that the relay is stuck closed, the control circuit is configured to;

    attempt to close the relay;

    attempt to open the relay;

    monitor the detect signal; and

    determine whether the relay is stuck closed.

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