Different CT Secondary

[vreijb]

The transformer HV side CTs at SWG are 500/5A and LV side at TR are 800/1A. The Transformer is 5MVA 7.2x4.16KV.
Can the CTs be used for differential protection without interposing relays with GE 745

 

[lume7006]

Hello,

Seeing only the CTR's and nominal currents in both sides, it seems that you may use them for your differential protection.
However, you must take a look at the class of the CT's, it is very important to be sure that:
They are C class, it means for protections
The C class is usually defined with a number C-50, C-100, C-200, and so on.

Once you have these data, you need to evaluate the maximum fault current on both sides to determine that there is not saturation on both CT's.
After this analysis, you will be sure if the CT's can be used for your 87T protection.

Regards

 

[Rodmcm]

I think you have a problem. The 745 can be purchased with 1A CTS and 5A Cts, you cannot mix