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Ground fault detection system

  • US 9,024,639 B2
  • Filed: 03/31/2011
  • Issued: 05/05/2015
  • Est. Priority Date: 03/31/2011
  • Status: Active Grant
First Claim
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1. A ground fault detection system comprising:

  • A single optocoupler connected to a second voltage source, a current sink, a first node at a ground zero reference level, and a second node at around;

    wherein said current sink comprises;

    a first resistor; and

    a first transistor;

    wherein said current sink is electrically connected in series between said optocoupler and a terminal of a battery pack comprising one or more battery units, andwherein a first voltage source. that provides a potential below the lowest potential of a battery pack, is connected in series between said current sink and said battery pack,wherein the first voltage source is connected to a negative terminal of a battery unit,wherein a first node at a zero reference level is an enclosure around portion of said battery pack; and

    wherein upon connection between a battery unit to said first node, current flows through the optocoupler and the current sink to cause the optocoupler to output a ground fault detection signal to an output node, and whereby the output node is electrically connected with said second node, and whereby said second node is electrically isolated from said first node;

    whereby current only flows through the ground fault detection system when the battery is electrically grounded.

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