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Ground fault trips at half of setting

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  1. joenavymctest is offline
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    Ground fault trips at half of setting

    I have a ground fault test that keeps tripping at half of the setting value. The system has one main circuit breaker, with one CT around the neutral. No trip test comes out fine (current in line side of CB, out of load side, into load side of neutral, through CT, and out of line side of CT). Trip test reversing though CT yields have of the setting value (about 217A vice 400A).

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    What is the CT ratio and what is the relay set to? My first thought is polarity but this cant be the case if no trip came out fine. What was neutral to ground megger readings?

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    Quote Originally Posted by joenavymctest View Post
    I have a ground fault test that keeps tripping at half of the setting value. The system has one main circuit breaker, with one CT around the neutral. No trip test comes out fine (current in line side of CB, out of load side, into load side of neutral, through CT, and out of line side of CT). Trip test reversing though CT yields have of the setting value (about 217A vice 400A).
    It would be easy to analyse if you could provide a simple sketch of what exactly the connection is..? and are you performing a test using secondary injection kit.?

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    Any verdict on this one? It's been about a week since OP. I agree a sketch would make it easier to analyze the situation.

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    Ground or Neutral ?

    Quote Originally Posted by joenavymctest View Post
    I have a ground fault test that keeps tripping at half of the setting value. The system has one main circuit breaker, with one CT around the neutral. No trip test comes out fine (current in line side of CB, out of load side, into load side of neutral, through CT, and out of line side of CT). Trip test reversing though CT yields have of the setting value (about 217A vice 400A).
    You stated this is a ground fault test and it sounds like it is connected as a neutral test. Are these settings the same?

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