To avoid this problem, the recommended grounding method is to install a single ground point at one point, either at the switchboard or at the relay panel. This article explains why CT secondary is grounded, how CT earthing works, and why CT secondary is shorted and grounded at only one point as per IEEE and ANSI standards. Abstract—Typically, high-voltage transmission systems are effectively grounded through the wye windings of transformers and autotransformers. If a ground fault occurs on the system, a ground overcurrent relay or impedance relay recognizes the zero-sequence current flow and takes the appropriate. Power transformer protection varies with the application and transformer importance.
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