MEASUREMENT OF THE EARTH FAULT LOOP IMPEDANCE IN A LOW-VOLTAGE NETWORK WITH OPERATING LOADS

S. Czapp∗

Keywords

Lowvoltage systems, earth fault loop impedance, measurement, errors

Abstract

This paper presents problems of the accuracy of earth fault loop impedance measurement in a network with operating loads. The classical measurement methods and meters used in practice cause measurement errors in a network with operating loads that may exceed permissible level. The most dangerous are negative errors, as in the case of line-to-earth fault, the automatic disconnection of supply may not occur and a risk of electrocution exists. Errors due to operating loads can be eliminated using the new method. Analysis of the measurement errors according to the new method is described. The results of analysis indicate that the effect of the operating load is eliminated. The new earth fault loop impedance meters can have wide application in the low-voltage systems.

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