抄録
In order to clarify the grounding conditions for protecting workers on the de-energized circuit from induction due to the live circuit and the required current capacity of grounding conductor for a 1, 000kV double-circuit power transmission line, the phenomena caused by the electromagnetic induction resulting from the live circuit are discussed here following Part 1, Electrostatic Induction. The results are as summarized below.
(1) The electromagnetic induction current Ig flowing through a worker and the electromagnetic induction current Ig0 flowing through the grounding conductor can be clearly discussed by dividing the various power line conditions into three main factors, and also by using the results of electromagnetic induction current calculations of a power line having an infinite length.
(2) The zone, where Ig does not exceed 1 mA, is within 1 km from the grounding point on the de-energized circuit, due to the grounding resistance (0.1Ω) of substations at both ends of the line and the difference in the phase configulations on the line when the currents I1 at the live circuit is a constant 1 kA through the line.
(3) In the same manner, the current value of Ig0 is determined by the grounding resistance of substations at both ends of the line and the difference in the phase configulations on the line. Also, Ig0 is approximately 10 A per 1 kA of I1.
(4) The current Ig and Ig0 due to the effects of electrostatic induction, and Ig and Ig0 due to electromagnetic induction act in such a manner that the former Ig is added to the latter Ig. This is also the case with Ig0. Thus, Ig and Ig0 in the actual power line can be respectively evaluated as the sum of absolute values for both the former and the latter values.
