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Relay switch control and related methods

  • US 10,209,751 B2
  • Filed: 02/13/2013
  • Issued: 02/19/2019
  • Est. Priority Date: 02/14/2012
  • Status: Active Grant
First Claim
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1. A relay switch control comprising:

  • a processor configured to receive control signals from a thermostat and having an internal analog-based clock upon which an operating frequency of the processor is based, whereby the cycles of the internal analog-based clock and the operating frequency of the processor of the relay switch control are individualized to the relay switch control; and

    a relay operable by the processor, in response to thermostat control signals, to electrically connect or disconnect a load to or from a voltage input received by the relay switch control from a line voltage source, where the relay switch control is configured for connection between the line voltage source and the load;

    the processor of the relay switch control further configured to;

    detect a line voltage signal indicating startup of line power to the load;

    detect a zero crossing of a signal of the line voltage source;

    upon detection of the zero crossing of the signal of the line voltage source, store at least a portion of a current value of a counter of the processor, wherein the counter is configured to update based on the cycles of the internal analog-based clock, whereby the stored value of the counter is based on a time of detection of the zero crossing of the signal of the line voltage source and individualized to the relay switch control; and

    combine the portion of the stored value of the counter with a value of a cycle period length of the line voltage signal to obtain a randomized number for use as a time delay before startup of the load, whereby the time delay is random and individualized to the relay switch control based on line voltage signal and relay switch control determinants;

    the relay switch control configured to start power to the load from the line voltage source through the relay after the time delay.

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