Why delta – delta CT’s are used for star – star transformer differential protection?

Why delta – delta CT’s are used for star – star transformer differential protection?
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1 Answer

Answer :

Say primary neutral is not solidly earthed. Then for any earthfault on secondary terminal, the primary current distribution is so for external fault, the differential is likely to operate if sequence current from flowing into relay. The 2:1:1 distribution is possibly only for core type or delta tertiary.
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Related questions

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Description : How Transformer Protection provided for internal faults?

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Description : Explain the “Differential Protection Scheme” used for alternators with neat labeled diagram.

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Explain differential protection scheme for busbars with neat sketch.

Description : Explain differential protection scheme for busbars with neat sketch.

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Description : Explain differential protection of busbar.

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Description : A series resistance is added to the over-current relay in a bus bar differential protection scheme which: a. Helps to develop some voltage across it which otherwise should appear across the relay and is ... the effects of CT saturation and lowers the pickup value of the relay d. All of the above 

Last Answer : A series resistance is added to the over-current relay in a bus bar differential protection scheme which: a. Helps to develop some voltage across it which otherwise should appear across the relay and is ... the effects of CT saturation and lowers the pickup value of the relay d. All of the above