VFTO computation in 420 kV GIS

摘要

This paper presents the results of Very Fast Transient Overvoltage (VFTO) computations that have been carried out using EMTP for various switching conditions in a 420 kV gas insulated substation. The variation of VFTO peak along the nodes for disconnector and circuit breaker operations as well as the variation of VFTO with different trapped charges have been studied. The results indicate a distinct pattern of variation of VFTO peak along the nodes of the GIS in the case of disconnector switch operation as compared to that of circuit breaker operation. It has also been noticed that the variation of VFTO peak levels are not proportional to the increase in the trapped charge.