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240.21 Protecting feeders, feeder taps and transformer secondary with protective relaying

Question asked by Chris Gorham on Sep 12, 2017
Latest reply on Sep 12, 2017 by Chris Gorham

240.21 Protecting feeders, feeder taps and transformer secondary with protective relaying, current transformers and "transfer tripping" of supply side of each from an interrupting device located remotely to the overcurrent protection device(Current transformer and Relay combination)

 

Does anyone have a historical precedent for applying protective relays to replace fused switches or molded case/power circuit breakers with integral trip units with a combination of current transformers and relays installed in the locations required by 240.21 but having interrupting devices installed further upstream even on the primary side of a delta-wye transformer?

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