CTs C400 versu C200

[spgustin@gmail.com]

Any reason I cannot use C200 CTs for this switchgear if the transformer CTs are C400?

 

[jim dungar]

it depends?
Why are there CTs in the first place?

If these are for customer owned protection then they can decide on which accuracy class they want and what risk of saturation they want to tolerate.
If these are for sensitive relaying purposes and fault currents are high, the increased accuracy may be important.
If this is utility equipment boilerplate specifications and standardization will probably dictate what you can use.

 

[topgone]

I maybe late but the reason for choosing the CT classification is to see to it that the CT won't give false outputs (saturated) when the CT is subjected to the fault current in the setup. In your example, if the fault current available is below 4.7 kA, you can use C200 CT (assumptions: length of CT wiring, one way is less than 50 feet and CT wiring used - 12 AWG).