Effect of Roof Height on Internal Arc Testing of Switchgear Panels

Abstract

The market requirements for Medium Voltage (MV) metal enclosed switchgear are getting more and more stringent. Bothbuilding costs as well as the level of the transmitted and distributed electrical power have increased rapidly over the recentyears and are expected to continue to rise. This means that switchgear manufacturers must bring more and more compactand powerful systems on the market, while being simultaneously as cost effective as possible. Internal Arc Classification(IAC) of switchgear according to IEC and IEEE standards is one of the most important requirements to guaranteesafety in case of internal arc faults. Internal arcs cause a sudden pressure rise in electrical installations. This leads to anextreme pressure stress acting on switchgear compartments and switchgear rooms and could cause collapse of buildingsThis paper describes few important design rules and innovations, which were necessary to achieve best results duringinternal arc tests. Furthermore it demonstrates the effect of roof height during the internal arc test with the important casestudies. Finally the best solution to eliminate the roof effect is also proposed.