Development of an On Line Monitoring System for Partial Discharges on Hydrogenerators

In this paper is presented the developing of a partial discharge (PD) monitor device that was designed to measure on line the hydrogenerators partial discharge activity in CVG EDELCA generators. The equipment measures the average of the peak values of PD between 3-9 MHZ bandwidth, from a signal taken through capacitive couplers placed at the end bars of the generator stator winding. The signal is filtered and conditioned to obtain a DC signal proportional to the value of the PD for its indication in a digital display. The monitor will allow the machine operators to verify the condition of the generator insulation at anytime, and alert the test engineer when a detailed diagnostic of generator insulation is necessary. The device also has an alarm circuit that is activated when the value is greater than a preset magnitude