Thermal effect on electric power network components under short-circuit currents

Abstract

In this work a mathematical model is proposed regarding the temperature rise estimation in components installed to electric power distribution networks (e.g. circuit breakers, automatic switches, disconnectors, fuse carriers), during short-circuit faults. The overall short-circuit current waveform and the components’ mass and material are considered. The model was applied to a common disconnector of the network and characteristics of the results are plotted according to different forms of the asymmetric part of the short-circuit current waveform and the initial value of the short-circuit d.c. current component. The models’ response is also investigated for a wide range of values of the crossing resistance and the component mass. It is convincingly shown that the short-circuit current waveform asymmetric part and component mass significantly affect temperature rise, and calculations of temperature rise which omit the above factors are questionable. An easy to use approximating equation is proposed, which could be considered in the mathematical approach of the phenomenon, according to international standards and facilitate the above components design.