Neutral Current Transformer

Those are already design outputs, no design activity is left in that except for few things like insulation consideration etc,All needed is fabrication based output you suggested.

All the CT across the world may not have uniform standard,Chose standard based on Who is the buyer, Where to be used?Or you should disclose more details so that members knows that may help you,

VA is needed to design the CT/or any transformer, But since transformer is already designed thats why he has not given you VA, if you fabricate the transformer with the said requirement It will meet the VA requirements automatically, If who so ever gave you those details is a qualified person,

Thank u for the opinion.

Best Regards,

M.R.Thayalan

1. Yes! It is possible to calculate the rated burden of the CT with the given inputs, but it is a cumbersome calculation.

2. The accurcay class of the neutral CT depends upon the application. If it is for REF (Restricted Earth Fault) Relay then you might need Class PS. If it is for back-up earth fault protection, then may be Class 5P10 or 10P10 might do. Else, if it is for metering (which, I doubt), then yopu should go for Class 1.0 or Class 0.5.

Mr. Dayalan, from the Secondary current of the CT and with the values of lead resistances, Relay resistance, And CT Internal resistance we can arrive at a tentative value of the Actual Value of the Burden.

It can be derived as VA or Burden = Is x (2x Lead Resistance + Relay Resistance + CT internal Resistance).

I request other members to please come up with comments on this answer.