Measurement of partial discharges on operating turbine generators with a novel wideband coupler

A novel PD (partial discharge) sensor has been developed which is able to unequivocally differentiate between PD in the winding and all types of electrical interference. This sensor, known as the stator slot coupler (SSC), is a wide-bandwidth directional electromagnetic coupler. The sensor requires no high voltage connection to the winding, and is easily installed in the stator slot, underneath the wedges. Using the inherent low-pass filter characteristic of the stator winding and the wide bandwidth of the SSC, noise is differentiated from PD by the shapes of the electrical pulses from the sensor. Experiments on operating turbine generators on which SSCs are installed have validated the theory of SSC. In addition, these installations have shown that the SSC does not degrade the overall reliability of the host generator.<
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