Failure mechanism of winding insulations in inverter-fed motors

Yin, Weijun

doi:10.1109/57.637150

Cited by 208 publications

(41 citation statements)

References 14 publications

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“…In the case where the pulse width matches the natural resonant frequency of the circuit, the overshoot can reach a maximum that is considerably higher in amplitude; hence, high dv/dt. As a result, temperature rise due to internal discharges can exist [7,8]. Figure 8 shows the frequency spectra of various voltage waveforms used in this study.…”

Section: Resultsmentioning

confidence: 99%

“…The adverse effects are the combined effects of high dv/dt, high repetition pulse rate, and the harmonic contents. Thus, no clear clues can indicate which one contributes more than others to the insulation failure of a motor [8]. In order to improve the insulation system of large high voltage form-wound motors, motor coil insulation should be tested with a similar voltage waveform close to the VSCs.…”

Section: Introductionmentioning

confidence: 99%

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Form wound stator insulation system under different voltage waveform stresses

Jayaram

2009

2009 IEEE Electrical Insulation Conference

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The paper presents the experimental results under power frequency, exponential decay pulse, square and sinusoidal pulse width modulated (SPWM) voltage waveforms, with the same peak values, applied to the insulation system of a form wound stator coil. Both the infrared images and the maximum temperature rise of the coil under different electrical stresses were recorded. Results show that the temperature rise of the coil surface under square wave or SPWM wave stress are much higher than the temperature rise observed under the stress of power frequency sinusoidal voltage or exponential decay pulses. FFT analysis shows that both the square and SPWM waveforms used in this study contain significantly higher harmonic components, similar to a real drive output voltage; hence resulted in a higher temperature rise compared to the other voltage waveforms used. Thus, neither the power frequency sinusoidal voltage nor the fast repetitive exponential decay type pulsed voltage can fully represent the transients caused by a voltage waveform of a real drive; voltage source converter.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Form wound stator insulation system under different voltage waveform stresses

Jayaram

2009

2009 IEEE Electrical Insulation Conference

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“…Power electronics switching devices currently represent the dominant technology for supplying power to new, industry performance low voltage motors. The fast switching processes exert a different class of stress on dielectric insulating materials than standard sinusoidal excitations [1,2]. Such stresses result in an increase in the dynamic activity of the working electric field, which in turn lead to an increased likelihood of partial discharges (PD).…”

Section: Introductionmentioning

confidence: 99%

“…In the last decades, the influence of Pulse Width Modulated (PWM) voltages, creating sequences of almost rectangular (semi-square) voltage pulses with very steep slopes and high switching frequencies, generated by modern electronic inverters of variable speed drives (VSDs) with very fast solid-state switches (e.g., IGBT, MOSFET), is a topic which has received considerable attention. PWM voltage waveforms with very fast slopes cause overvoltages with relatively high values, generated due to transmission line phenomena and resonances, that stress insulating systems of feeding cables and motors [1][2][3]. These factors change conditions for processes of space charge accumulation, which influence on initiation and dynamics of PD development in electrical insulating systems [4].…”

Section: Introductionmentioning

confidence: 99%

Partial Discharges in Insulating Systems of Low Voltage Electric Motors Fed by Power Electronics—Twisted-Pair Samples Evaluation

2019

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Power electronics switching devices currently represent the dominant technology for supplying low voltage (LV) electric motors. The fast switching processes exert a different class of stress on dielectric insulating materials than standard sinusoidal excitations. Such stresses result in an increase in the dynamic activity of the working electric field, which in turn lead to an increased likelihood of partial discharges (PD). The stator design of low voltage motor is often in form of random-wound windings, where the magnet wires (copper or aluminum round wires coated with thin layer of insulation) form a common system of coils with not precisely defined mutual position of particular turns, resulting in various turn-to-turn and coil-to-coil voltage distributions. Pulse Width Modulated (PWM) voltage waveforms from modern electronic inverters are characterized by very short rise times and presence of repetitively occurring overvoltages that can significantly stress the insulation of feeding cables and motors. These factors influence the inception and dynamics of PD and processes of space charge accumulation in electrical insulation. In this paper investigations performed on round magnet wire twisted-pair samples representing LV motor random-wound winding elements are presented. Special attention was afforded to the twist configurations, observed breakdown voltage and PD activity. To describe the field conditions for the formation of PD in the turn-to-turn insulation system, the results of numerical simulations of electric field distributions for winding wires with different diameters, modeled using the COMSOL program, were analyzed. PD created in the insulating systems of model twisted-pair systems were registered and analyzed using the phase resolved partial discharge analysis (PRPDA) method.

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“…The adverse effects on the performance of power system components such as transformers, cables and accessories in the presence of fast transients and high frequency components have been reported recently [2]. Further, transformer failures have been documented by wind-farm developers.…”

Section: Introductionmentioning

confidence: 97%

Effects of voltages with high-frequency contents on the transformer insulation properties

Khanali

Jayaram

Cheng³

2013

2013 IEEE Electrical Insulation Conference (EIC)

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This work studies the changes that occur in transformer insulation properties when voltages with steep fronts and high-frequency contents are applied. With a significant growth in the number of wind-farms and solar-plants that use power-electronic-based converters, the problems associated with such voltages on insulation has led to increasing concerns. Distorted voltages accelerate the transformer insulation degradation. Two identical transformers are studied by energizing independently under power frequency sinusoidal and width-modulated pulse trains. The dielectric characteristics of the test objects, like partial discharge activities, insulation resistance, are periodically measured during the ageing process. After a period of 500 hours of testing the dissolved gases are also analyzed. The results for both transformers are compared and discussed.

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Failure mechanism of winding insulations in inverter-fed motors

Cited by 208 publications

References 14 publications

Form wound stator insulation system under different voltage waveform stresses

Form wound stator insulation system under different voltage waveform stresses

Partial Discharges in Insulating Systems of Low Voltage Electric Motors Fed by Power Electronics—Twisted-Pair Samples Evaluation

Effects of voltages with high-frequency contents on the transformer insulation properties

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