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Here's why you should always short a CT secondary

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  1. SecondGen's Avatar
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    Here's why you should always short a CT secondary



    Care must be taken that the secondary of a current transformer is not disconnected from its load while current is flowing in the primary, as the transformer secondary will attempt to continue driving current across the effectively infinite impedance up to its core saturation voltage.

    This may produce a high voltage across the open secondary into the range of several kilovolts, causing arcing, compromising operator and equipment safety, or permanently affect the accuracy of the transformer.

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    Quote Originally Posted by SecondGen View Post


    Care must be taken that the secondary of a current transformer is not disconnected from its load while current is flowing in the primary, as the transformer secondary will attempt to continue driving current across the effectively infinite impedance up to its core saturation voltage.

    This may produce a high voltage across the open secondary into the range of several kilovolts, causing arcing, compromising operator and equipment safety, or permanently affect the accuracy of the transformer.
    Unless that ct is going to be put in service..., make sure those shorting screws are out prior to energizaton.

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    Nice video btw

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    Quote Originally Posted by codycody103 View Post
    Unless that ct is going to be put in service..., make sure those shorting screws are out prior to energizaton.
    Wow! I have never tried that!

    And you can verify the secondary circuit integrity with the secondary injection function of my CT test set.

    See www.cttestset.com and read all about it.

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    Quote Originally Posted by codycody103 View Post
    Unless that ct is going to be put in service..., make sure those shorting screws are out prior to energizaton.
    Cody,

    Why do you mention "to remove shorting screws prior to energizing"? If you forget to remove them and energize the circuit, just remove them after energizing.

    Unless your point was to make sure you don't defeat your protection devices, then you would want to make sure shorting screws are removed before you walk away for good.

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    Quote Originally Posted by codycody103 View Post
    Unless that ct is going to be put in service..., make sure those shorting screws are out prior to energizaton.
    Excellent video. Thank you.

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    Quote Originally Posted by SecondGen View Post


    Care must be taken that the secondary of a current transformer is not disconnected from its load while current is flowing in the primary, as the transformer secondary will attempt to continue driving current across the effectively infinite impedance up to its core saturation voltage.

    This may produce a high voltage across the open secondary into the range of several kilovolts, causing arcing, compromising operator and equipment safety, or permanently affect the accuracy of the transformer.
    Good post. Nice video, too. I was interested to see how the axe was going to come into play.

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