Definition: | protection in which the residual current from a set of three-phase current transformers is balanced against the residual output from a similar set of current transformers or, more usually, from a single current transformer located on the earthing connection, if any, of a neutral point
NOTE – This term is also used when the neutral of the protected plant is unearthed i.e. neither a second set of three-phase current transformers nor a current transformer in the neutral connection is needed to restrict the protected section.
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