earthing of current transformer

I think it's a safety precaution against possible 'open circuit' on the CT secondary side, which can lead to generation of dangerously high voltage.

Tilak

It is provided to flow the earth fault current.

Check previous threads. covered many times.

Check your text book,

During a secondary open circuit on one CT, a very high transient voltage would appear across all the three phase CTs as they are interconnected through the loads. If you earth one terminal of the secondary of all the three phase CTs, the insulation need to be done only for phase voltage and not for line voltage. This greatly reduces the size and insulation cost of the CT. There is a dedicated IEEE Standard on this topic.

Dear all,

CT Primary and secondary is linked though stray capacitance and resistance of insulator.

If CT secondary is not earthed, the primary voltage may induce high potential in secondary winding. Too keep the secondary voltage as we wish such as 110V against the earth, secondary must be earthed.

Regards