A simulation model is set up in order to calcu-late the conductive disturbing voltage in secondary circuit caused by disconnector or circuit breaker operations in GIS.In this model
the high frequency capacitive PT/CT model and the multi-terminal network model for grounding system are included using rational functions by means of vector fit-ting based on test data.By incorporation them into EMTP
one can use this conductive coupling model of GIS to cal-culate not only the very fast transient Overvoltages(VFTO)and Transient Ground Potential Rise(TGPR)in the primary circuit but also the disturbing voltage in the secondary cir-cuits in GIS.