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发表于 2009-7-15 14:47:05
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In addition to Story 14 ywhywh," l* O; f" K" _7 s7 A ?5 i
The 3phase system has two types, delta and Y. Delta is un-earthed and Y is earthed. Delta is similar to DC system while you have electricity flow in 3 wires and Y has a netural connection connected to the earth. When an earth fault happens, the fault current will always return to the source (i.e. not necessarily to be the generator, but can be the transformer where it is grounded. Transformer is like an isolation point) via the ground. I recommend you read IEEE Std 80 to gain further understanding. |
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