Ground Switch Interrupting Duty and Total Ground Current Imposed by Induction from Parallel Transmission Lines

Induction from parallel energized circuits imposes an interrupting duty on ground switches and causes the injection of currents in the ground at switch locations. Both the electrostatic and the electromagnetic induction levels are given for the different voltage class combinations between the energized and the de-energized circuits in the range 69 kV to 1150 kV. A comprehensive study of the factors affecting the induction levels is included. The electromagnetic induction levels are shown to be much higher than the electrostatic induction levels. It is also shown that the maximum ground switch interrupting duties exceed the capabilities of many existing installations.