Estimation of Pressure and Temperature Rise Due to Internal Arc Generation in Switchgears

Abstract

The switchgears are vital component in energy system which protects, regulates and isolates the electrical transmission line by making or breaking the high voltage circuit with the use of circuit breakers. During the operation of switchgear internal arc is a failure criterion which is a result of a short circuit current. To quench this arc, the internal arc chamber is used which encapsulates the energy generated and protects the further transmission system and appliances. The gas insulated switchgears used for medium voltage application are enclosed inside the metal chambers and thus design of these chambers becomes crucial as they handle high pressures and temperatures. This fact is also exacerbated by the condition that metal chambers are prone to sudden increase in pressure due to internal arc phenomenon. The type testing process used for validating the design of chamber against internal arc is time consuming, costly and thus shall be performed with no margin of error. The paper aims to establish the standardized approach to calculate the instantaneous pressure and temperature rise inside the gas tank of switchgear which are otherwise impossible to approximate given the short timeframe in which internal arc occurs by using the approaches discussed in the CIGRE committee reports.