Method for determining insulation thermomechanical deterioration of VPI wire rod of pumped storage power generation motor

A method for determining insulation thermomechanical deterioration of a vacuum pressure impregnating (VPI) wire rod of a pumped storage power generator motor, comprising:

• periodically performing a cold-heat cycling test on the wire rod, and performing an insulation dielectric dissipation factor testing and a result interpretation of the insulation dielectric dissipation factor testing before and after each period of the cold-heat cycling test to obtain corresponding data;
• in response to determining an interpretation result as the data being qualified, continuing to perform the cold-heat cycling test;
• and
• in response to determining the interpretation result as the data being unqualified, striking the wire rod with a copper hammer, and performing signal processing by using an acoustic acquisition and analysis system to determine spectral characteristics in a thermomechanical deterioration state as a deterioration criterion;
• wherein the cold-heat cycling test uses a manner that the copper conductor is heated by a current and cooled by ventilation, each period of the cold-heat cycling test has 50 cycles, and each of the 50 cycles has a temperature of 40° C. to 130° C. and a temperature ramp rate of 2.5° C./min±1° C./min:
• wherein in the insulation dielectric dissipation factor testing, testing voltages comprise 0.2 UN, 0.4 UN, 0.6 UN, 0.8 UN, 1.0 UN, and 1.2 UN, wherein UN is a rated line voltage;
• and the method comprises:
• in response to determining that magnitudes measured at a plurality of voltage points satisfy the following conditions at the same time, determining that the data is unqualified;
• and in response to determining that the magnitudes measured at the plurality of voltage points do not satisfy the following conditions at the same time, determining that the data is qualified:
• a magnitude measured at 0.2 UN<a magnitude measured at 0.4 UN<a magnitude measured at 0.6 UN′ a magnitude measured at 1.2 UN<a magnitude measured at 1.0 UN<magnitude measured at 0.8 UN<the magnitude measured at 0.6 UN;
• a difference between the magnitude measured at 0.6 UN and the magnitude measured at 0.2 UN>1%;
• and the magnitude measured at 0.2 UN>1%.