New technology for partial discharge testing of operating generators and motors

Partial discharges (corona) are a symptom of most types of deterioration of high voltage motor and generator stator windings. A new type of partial discharge test is described. It can be performed by plant personnel during normal operation of the machine. The key requirement of the new test is to remove all the interference caused by other sparking and discharging sources in a plant. The test uses either high voltage capacitive sensors or 1000 MHz electromagnetic couplers to detect the discharge signals. The signals are processed by a specialized electronic instrument to remove noise. this test is specially designed for high speed machines.