Simulations and Measurements of the Pre-Arcing Times in HBC Fuses Under Typical Electric Faults

Abstract

This work deals with the comparison between calculations and measurements of pre-arcing times in High Breaking Capacity fuses under typical fault current conditions. This paper also describes the temperature evolution and the Joule energy dissipated in a fuse element during the pre-arcing time. By varying typical electrical parameters, namely the closing angle and the power factor, we show that various prospective currents such as those observed in industrial case can be fairly simulated. The pre-arcing time and then the clearing of the fault current are shown to be deeply dependent on these electrical characteristics. We exhibit simulated results of prospective current and supply voltage waves for given closing angles under two typical power factors which are compared with the experimental ones. A comparison between simulated pre-arcing times with experimental ones shows some discrepancies and a discussion on the numerical assumptions is made.

Electric fuses operation, a review: 1. Pre-arcing period

“…As the pre-arcing period is usually defined as the time necessary to reach the melting point of the fuse element metal, many modellings can be found including comparisons with measurements. Among the whole of these studies one may distinguish pre-arcing period considered under adiabatic assumptions [15] (very short pre-arcing times or high fault current level), pre-arcing period considered by taking into account the whole of the physical processes responsible for the energy withdrawal [13,15] and all the intermediated cases where various simplifications are made depending on the operating conditions [52]. Phenomenological modellings have been also published [25]: the electric fuse is described by means of an equivalent electrical circuit built on resistive and capacitive contributions, according to parallel and series schemas.…”