Detection of Slot Discharges in High-Voltage Stator Windings During Operation

A modified slot discharge detection method, which permits tests without Shutting down the machine or using auxilliary high-voltage test equipment, was investigated. The method involves connection of frequency sensitive equipment across all or part of the ntral impedance. Tests on eight vertical water wheel generators in the range of 20,000- to 40,000-kva capacity indicate that the method is generally applicable when there is a current transformer or some other impedance in the generator neutral.