Field Research on Very Fast Transient Overvoltage in 750kV GIS Substation

Very fast transient overvoltage(VFTO)in GIS has been abundantly researched in China and abroad.The technology is relatively mature,but there are still some technology problems in practical measure.Three practical measure methods for the very fast transient overvoltage that are inside outside very fast transient overvoltage and transient enclosure ground potential rise(TGPR)are introduced in this paper.This paper also gives the circuit breaker's VFTO measure dresults in switching of no-loaded lines for 750 kV CIS in eastern Lanzhou,which provide a direction for field measuring the very fast transient overvoltage.