Optimum settings for the 100% ground-stator protection in the Tucurui, Balbina and Samuel hydro-power plants-Eletronorte-Brazil

One of the most upsetting problems reported during the commissioning and initial operation of the generator units installed in the Tucu-Rui, Balbina and Samuel hydroelectric power plants in the Amazon Basin-Brazil is related to the performance of the 100% ground-stator protection which method of detection is third harmonic-based. The authors present simple but efficient third harmonic monitoring techniques experimented by Eletronorte-BKP/Copertec for its correct evaluation in potential transformer secondaries connected to either the generator neutral or the generator terminals. As a result, the third harmonic content in a generator, as a boundless discriminator for faults close to the neutral, can be better criticized