Typical expected values of the fault resistance in power systems

Abstract

This article presents a range of possible values for the fault resistance in transmission power systems, considering six existing models for the arc resistance and a model for the grounding impedance of the towers. Resistance by possible additional objects in the path of the fault current was not considered. Known the short circuit level (without fault impedance), the fault resistance was calculated with the above mentioned models, for line-to-line and line-to-ground faults. This calculation was made for diverse nominal voltages and diverse short circuit levels for solid faults. The obtained range might be useful to improve the way of computing the settings for the corresponding protective devices.