A new sensor for detecting partial discharges in operating turbine generators

A partial discharge (PD) sensor has been developed which is able to unequivocally differentiate between PD in the winding and all types of electrical interference. Thus, the sensor will permit an online test for turbine generators, similar to the test now used for hyrogenerators. The sensor requires no high-voltage connection to the winding, and is easily installed in the stator slot, underneath the wedges. Noise is differentiated from PD by the shapes of the electrical pulses from the sensor. The sensor, called the Stator Slot Coupler (SSC), is essentially a directional electromagnetic coupler. Calculations as well as laboratory tests indicate that the couplers can easily survive the electrical, thermal, magnetic, and mechanical stresses in the generator