Hello Abhi,

The attached snapshot is of differential current protection relay circuit, mainly for EHV transformer. It works on balance current principal in primary & secondary winding of transformer .

Its CT ratio is selected in such way that, primary & secondary CT current should be same/equal. For primary delta winding CT is connected in star & secondary star winding CT is connected in delta. Across CT output, balance current protection relay coils are connected, which operates & open breaker to safeguard transformer in case any abnormality is detected,

Please refer Differential Protection of Transformer | Differential Relays article for more detail information.

Hope this helps.

PISCEAN 2010

Hello Abhi,

The attached snapshot is of differential current protection relay circuit, mainly for EHV transformer. It works on balance current principal in primary & secondary winding of transformer .

Its CT ratio is selected in such way that, primary & secondary CT current should be same/equal. For primary delta winding CT is connected in star & secondary star winding CT is connected in delta. Across CT output, balance current protection relay coils are connected, which operates & open breaker to safeguard transformer in case any abnormality is detected,

Please refer Differential Protection of Transformer | Differential Relays article for more detail information.

Hope this helps.

 

 I have already read this article. Thanks.