current transformer (CT) circuits. This Powell Technical Brief investigates the preferred ground location of typical current transformer circuits such as transformer and bus differential relays.EEE standard C57.13.3 serves as the ANSI guide to standardize instrument transformer grounding practices. The grounding of current transformers is important to both safety and the correct operation of protective relays.To assure safe and reliable operation, the neutral of the current transformer secondary should have a single ground location for each circuit. The single ground is irrespective of the number of current transformers or the chosen grounding location. Utilizing a single ground eliminates the risk of redundant ground loops and associated problems
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