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What is the Restricted earth fault protection and how to implement on Low Voltage ?

The restricted earth fault protection (ANSI 64REF) can be applied if the downstream power system neutral is earthed at the transformer (document attached).
This is a differential protection function that detects the difference between residual currents measured at the neutral earthing point and at the three-phase output of the transformer.
Please find attached document describing how to implement the estricted earth fault protection with Masterpact Micrologic 6.0