Dr. Greg Stone
Thousands of short risetime voltage pulses per second are created by invertors of the pulse width modulated (PWM) voltage source type. These voltage pulses may adversely affect the stator winding insulation in variable speed motors and the rotor insulation in DFIG wind turbines and hydrogenerators. In random wound machines rated less than 690 V, partial discharge (PD) can occur that lead to insulation failure. In form wound machines, the inverter voltage pulses cause dielectric heating, higher PD and more rapid aging of the stress control coatings. This seminar reviews the characteristics of the voltage pulses from drives and the insulation failure processes. Avoiding insulation failure using the test methods described in IEC 60034-18-41 and 42 are also discussed.
Dr. Diego Robalino
This course describes the most important methodologies used for transformer insulation diagnostics in the field. The topics include frequency domain methodologies described in the international literature including line-frequency power factor, narrow band and full spectrum dielectric response as applied in power, distribution, instrument transformers and HV bushings.
Dr. Howard W. Penrose
This half-day seminar covers aspects of root-cause-failure-analysis (RCFA) of electrical insulation systems in electric machines. It will provide participants with a method and examples for approaching system failures utilizing an industry recognized process.