Restricted earth fault relay application on Shunt Capacitor Bank design with synchronized switching

This paper is aimed at analyzing the performance of restricted earth fault relay protection used in conjunction with controlled switching on a 400kV 100MVAR capacitor bank scheme used on the Eskom Transmission network. After the commissioning of the capacitor bank using the above mentioned scheme design the plant was energized. The capacitor bank then experienced spurious trips. The cause of the trips was the operation of the restricted earth fault relay. In this investigation, restricted earth fault protection on Shunt Capacitor Banks in the Eskom Transmission environment will be the area of interest. The research will analyze the current Shunt Capacitor Bank protection scheme in service specifically looking at the restricted earth fault circuit design and relay performance. An equivalent model of the Shunt Capacitor Bank from primary plant perspective based on theory is derived. Recording and analyzing of Comtrade transient waveforms respectively, when the bank is energized, will be done in order to provide a reference to work from. Manual calculations of various parameters from the derived model including harmonics, transients, inrush currents and fault currents will be performed to access scheme parameters.