Transient electromagnetic phenomena in the secondary circuits of voltage and current transformers in GIS (measurements and calculations)

The paper presents numerical and experimental evaluation of the transient behavior of Gas Insulated Substations (GIS). The electrical equivalent circuits chosen to represent the main components of GIS are implemented in the Electro- Magnetic Transients Program (EMTP). The effect of mutual couplings between phases are included in the model, which is of importance for analyzing a modern GIS, containing three-phases in one encapsulation. With the help of this model the generation and propagation of transients inside GIS have been evaluated with regard to transient overvoltages in the secondary circuits of voltage- and current transformers. The established model results have been successfully verified experimentally for a 123 kV GIS.