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CT theory

Johno12345
Im just reading about CTs, just for interest really. I have always known that you short CTs when they arent connected, but assumed it was just so you couldn't get a shock from the cable which would rise to the voltage on the cable its clamped around. I know this isn't quite right now.


Evidently, the voltage can rise to thousands of volts and damage the CT, I assume this happens instantly, rather than a gradual rise


The other thing, and this is my question really, if one side is grounded and commoned, as the drawings of them show, and the other side is open, does the voltage rise still occur? I just cant quite fathom it in my head
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    An open circuited CT will produce a very high voltage, often enough to destroy the transformer, and potentially to kill anyone coming into contact with this high voltage.

    Earthing one side of the CT does NOT reduce these risks. The only way to avoid the danger is never to open circuit a CT whilst current flows in the primary.


    Earthing CT secondary circuits is good practice for another reason, to avoid accidents if any inadvertent connection should occur between the CT circuit and the voltage circuit to say a KWH meter or other instrument.

    By convention or custom, such earth connections are often white, rather than green/yellow.
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    An open circuited CT will produce a very high voltage, often enough to destroy the transformer, and potentially to kill anyone coming into contact with this high voltage.

    Earthing one side of the CT does NOT reduce these risks. The only way to avoid the danger is never to open circuit a CT whilst current flows in the primary.


    Earthing CT secondary circuits is good practice for another reason, to avoid accidents if any inadvertent connection should occur between the CT circuit and the voltage circuit to say a KWH meter or other instrument.

    By convention or custom, such earth connections are often white, rather than green/yellow.
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