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| The picture shown tells how this device works. |
Earth Fault Indicator (EFI) is a part of a distribution network that is provided for each of the incoming cables in a ring circuit to indicate the faulty section during earth fault.
EFI is composed of an earth fault relay and indicator which is directly operated by a secondary current from the split-core type core-balance transformer. The indicator is automatically re-set by single phase 230V supply.
The split-core type core-balanced transformer is fixed to the cable termination box and has a ration of 60:1, accuracy of class 5 and burden of 1.5VA. Generally speaking, it should be sensitive to low magnitude earth fault current.
