Abstract: Abstract:The source injection type stator grounded fault protection in the protection cabinet A, B of Generator No.5 in Goupitan Hydropower Plant tripped, and this caused active load of the plant 527.6MW to be shed. The Bphase outlet potential transformer of the generator No.5 had been disassembled and tested, and it was found out that the main reason of load shedding of the 600MW generator is the damage of the potential transformer. The relevant countermeasures were proposed, which laid a solid foundation for the fault treatment.

Key words: Key words:source injection type stator grounded fault protection, potential transformer, turntoturn short circuit, reason analysis;measure