Simple Modelling and Characterization of Pressure Rise due to Internal Arcing in an Open Chamber with Releasing Through a Metal Grid

Abstract

In some electrical installations equipped with the pressure relief mechanism for the internal arcing fault, metal grids are set up at the releasing parts. So it is necessary to understand how the pressure in such electrical installations rises during the internal arcing fault. This paper describes an investigation of the internal pressure rise due to the high current arc in an open chamber with releasing through a metal grid. In this investigation, we focused on both the peak value P_peak and the time to peak t_peak on the internal pressure rise waveform where the oscillating component was removed, because it was experimentally observed that the general variation of such internal pressure rise with time had a point of turning from growing to lessening during the arcing. In order to investigate such internal pressure rise, a simple model for calculation was constructed, and was validated by a comparison with data from the experiment using a perforated metal plate as a metal grid. As a result of the investigation applying this simple model, the dependence of both the P_peak and the t_peak on conditions of the metal grid, the chamber volume, and the arc energy was derived quantitatively.