Switching Transient Studies

Switching transient studies typically analyze the transients associated with switching of utility or industrial capacitor banks or shunt reactors, or transmission line energization. They are sometimes performed as part of a forensic analysis of an equipment failure, particularly if the failure is associated with a switching event or operation of a protective device.

A capacitor-switching transient study is usually performed to evaluate the effects of transients on adjustable-speed drives at end-user facilities, particularly when there are concerns about the potential for voltage magnification occurring at power-factor correction capacitors. The study often includes evaluation of transient mitigation devices and the effects of restrikes in the capacitor-switching device.

A reactor-switching transient study evaluates current chopping in the reactor-switching device and the effects of transients on the reactor and connected cables. A line-energization transient study evaluates the effects of transients on surge arresters at the end of the line, along with the performance of transient-mitigation devices.

Switching transient studies are performed using the Alternative Transients Program, which is the PC version of the Electromagnetic Transients Program. Equivalent circuit models for ATP simulation are developed based on the parameters of the equipment involved and the frequency range of the phenomenon being investigated.