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Grounding Riddle No.33 - Two source with their own NGR
When two source have their own NGR ( Wye ground)- Zero sequence can not be detected correctly.
What would be the CT arrangement on both neturals ( one is on gen step up transformer and other on Grid step down transformer)  with communication to trip the right source. relay such as T60 ( MULTILIN) are used.

Author : Roxy - From: India
Wed, December 7th, 2011 - 16:35
It seems your problem is discriminative earth fault detection in a multi grounded system in source and load side grounding. The selective and ideal earth fault protection in multi grounding systems is difficult. One recommended solution for discrimination of earth fault protection is polarized or directional earth fault current protection. As you see in following figure, suitable directional earth fault relay can be the best solution.
Please correct me if I didn't underestand your question.

Author : Hamid - From: Iran - Firoozabad Fars
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