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Multiple power source automatic switching circuitry

  • US 4,044,268 A
  • Filed: 01/05/1976
  • Issued: 08/23/1977
  • Est. Priority Date: 01/05/1976
  • Status: Expired due to Term
First Claim
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1. Automatic switching and disconnect circuitry for connecting a load normally across a primary power source, for connecting the load across a secondary power source when the primary power has failed, for disconnecting the secondary power source when its voltage has been reduced below a predetermined cut-off point corresponding to no greater than about its 90 percent discharge level, and to reenable the primary power source when it has regained power comprising:

  • voltage responsive electromechanical switch means interposed between the primary and secondary power sources and operable between open and closed positions;

    first circuit means connected between the switch means and a tapping point at the primary power source for controlling the opening and closing of the switch means responsive to the voltage level of the primary power source;

    second circuit means connected between the secondary power source and the switch means for controlling the opening of the switch means, when the primary power source has failed, responsive to the voltage level of the secondary power source so that the secondary power source is automatically disconnected from the laod and any other discharge path in the circuitry with total latch out upon reduction of the voltage exhibited by the secondary power source to the cut-off point.

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