The Balbina Hydroelectric Power Plant has 250 MW electrical generating capability, distributed within five 50 MW units. The generators are rated as 55.5 MVA and 13.8 kV are of the low rotation umbrella type, driven by Kaplan turbines (105.88 rpm). Large hydro power plant with five units from different manufacturers, the last unit was operational in 1987. Generating units 1 to 4, from the same manufacturer, with lap winding, have had a high incidence of corona effect discharges.
Experimental reports indicate that PDs take place years before the failure, offering sufficient time to plan and execute corrective maintenance, which, in the case of HPP Balbina, after some attempts, assertively allowed to find an adequate solution that will be present in this paper.
The success of the procedure solution for strengthening the grading system for the bars, with no more occurrences of the defect, reduced maintenance time during the five- year schedules of planned maintenance, causing a lower cost in the workforce, reducing the unavailability rate of the generating units and, with that, contributing to a better commercial performance of the company. After reconfiguring the corona prevention system, PD monitoring indicates a decrease in the level of discharges and extinction of corona in the sleeves.
Corona Effect, Corona Discharges, Corona glove, Partial Discharges, Relief Interface
