Calculation of electrical parameters for transient overvoltage studies on electrical machines

Finite element models are developed for the calculation of the coil resistance, inductance and capacitance in rotating machine windings. Resistance and inductance are calculated by analyzing the time harmonic fields in the machine, taking into account skin and proximity effects as well as the magnetic flux penetration into the iron core. The capacitance is calculated by the analysis of the electrostatic field in the coil regions. The electrical parameters are obtained considering the contributions due to the slot and overhang sections of a preformed coil. The accuracy of the calculated electrical parameters was verified by a comparison of calculated results and test data in two high voltage motors. The calculated parameters can be used for developing machine winding models for switching transient studies.