×

Ground fault circuit interrupter with grounded neutral protection

  • US 4,180,841 A
  • Filed: 11/21/1977
  • Issued: 12/25/1979
  • Est. Priority Date: 11/21/1977
  • Status: Expired due to Term
First Claim
Patent Images

1. A ground fault protective apparatus for use on an AC electrical circuit having a line conductor and a neutral conductor grounded at a power source, comprising:

  • means for sensing current imbalance on said line and neutral conductors, said sensing means providing an output signal proportional to said imbalance;

    means for integrating said output signal and for providing a trip indication whenever said signal integration value exceeds a predetermined reference level;

    means for inducing a test voltage on said neutral conductor, whereby a current imbalance is produced between said line and neutral conductors which is proportional to the neutral-to-ground conductance;

    means for providing a reference current proportional to said test voltage;

    means connected to the input of said integrating means for comparing said reference current to the output signal of said sensing means, said comparing means supplying a signal current to the input of said integrator whenever the output signal of said sensing means rises above said reference current, said signal current being of sufficient amplitude to cause said integrator means to produce a trip indication.

View all claims
  • 0 Assignments
Timeline View
Assignment View
    ×
    ×