Calculation of electrical parameters for transient overvoltage studies on electrical machines
ABSTRACT 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.
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- "The results presented are for one coil in the slot, but the analysis can be extended for a greater number of coils connected in cascade in the winding. In this case, mutual couplings are calculated using the techniques presented in references  . Similar results were obtained for the series resistance. "
ABSTRACT: This paper describes a computer model for calculating the surge propagation in the winding of electrical machines. The model considers the winding as a combination of a multiconductor transmission line and a network of lumped parameters. The frequency dependence of the winding electrical parameters are calculated and incorporated into the analysis by means of Foster and Cauer circuits. Finally, this hybrid model is validated by a comparison of calculated and measured results inside a high voltage machine winding.
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ABSTRACT: Time domain terminal models for high voltage induction motor windings are developed for simulating transient overvoltages due to switching operations in industrial installations. The models are based on the network synthesis of the terminal impedance for short circuit and open circuit conditions of the winding. The process of synthesis is carried out taking into account the minimum and maximum resonant frequencies. The machine winding impedance is determined with a frequency domain model developed by means of the transmission line theory and using a finite element method for electrical parameter calculation. The computer models are validated by comparing the calculated transient overvoltages and the winding impedances against test data for a high voltage motorElectric Machines and Drives, 2005 IEEE International Conference on; 06/2005
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ABSTRACT: In order to study the very fast transient overvoltage (VFTO) distribution in the taper winding of a tesla transformer under high-frequency steep-fronted voltage surge, we built a distributed line model based on multiconductor transmission line (MTL) theory. We used a new hybrid algorithm combining finite-element-method (FEM) and interpolation formulas to quickly evaluate the induction coefficient matrix K by utilizing some characteristics of the taper structure. The turn-to-ground and interturn voltage distributions can be obtained by solving the telegraphist's equations in the frequency domain. We measured the voltage distribution inside the taper winding to find some ways to weaken the voltage oscillations. Here, we compare the results with numerical values.IEEE Transactions on Magnetics 04/2006; 42(3-42):434 - 441. DOI:10.1109/TMAG.2005.862759 · 1.39 Impact Factor