High-Voltage High-Frequency Testing for Medium-Voltage Motor Insulation Degradation

Mirza, Arshiah Yusuf; Chen, Weiqiang; Nguyen, Hiep H.; Cao, Yang; Bazzi, Ali M.

doi:10.1109/ecce.2018.8557568

Cited by 11 publications

(5 citation statements)

References 3 publications

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“…However, the electric field on the surface of the wire insulation between the wires is still sufficient to initiate PD for both the waveforms because ionization is surrounding the air gap along with surface potential decay [25]. A similar trend of results reported in [18]. For the increased voltage of 5.65 kV, the field value obtained is 46.6 kV/mm.…”

Section: Numerical Modeling Of Electric Field Distribution In Twisted Pair Samplesupporting

confidence: 80%

“…If instead of 1kV test voltage, 5.65 kV is applied the field would have been 39.55 kV/mm for the same 0.1 mm gap. However, the field obtained by [18], is 7 kV/mm for the test voltage of 1kV. Hence, 1337 the higher field obtained in this work is due to the high frequency of 10 kHz compared to power frequency and Square-rising wave compared to Sine wave.…”

Section: Numerical Modeling Of Electric Field Distribution In Twisted Pair Samplementioning

confidence: 60%

“…Hence, 1337 the higher field obtained in this work is due to the high frequency of 10 kHz compared to power frequency and Square-rising wave compared to Sine wave. Besides this, the € r value of the material used by [18], is 3.8-4.2 compared to the polyester material used in this work for which the € r value used is 3.3. The same is observed for 20 kHz and 30 kHz.…”

Section: Numerical Modeling Of Electric Field Distribution In Twisted Pair Samplementioning

confidence: 77%

“…The stator winding insulation is subjected to such high frequency stress which is a more realistic one. As observed by researchers that one cannot assume a theoretical deduction that low-frequency test data can be used to predict life with increasing frequency for all insulation systems, the test was done at 10 kHz [18] but the objective was to save the power loss rather than to know the life of the insulation. Hence an attempt is made in this work to test the twisted pair insulation with the higher frequency of 10-30 kHz to investigate the life of twisted pair enamel insulation.…”

Section: Introductionmentioning

confidence: 99%

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Modeling of high frequency high voltage of waveforms on life of enamel insulation

Rao¹,

Kasinathan²

2021

IJEECS

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<p>In recent years it has been observed that insulation failure in electrical motors is caused by adjustable speed drives fed by power electronic converters. These converters produce impulse waveforms having a high slew rate generated by the high switching frequency of IGBTs. This paper focuses on high switching frequency stress in low voltage electrical motors for adjustable speeds. To examine the motor winding insulation under such stress twisted-pair samples were developed from enameled wires. A single-coated polyester of enamel with a thickness of 40 microns is used for this work. High-frequencies, high voltages of Square, and Square-rising, Square-spike waveforms of 10-30 kHz are used here. The test results show that the insulation fails earlier for the Square waveform compared to the Square-spike and Square-rising waveforms. In a nutshell, there is an analysis of PD formation in the insulation system at a higher switching frequency is analyzed. Electric field distributions between twisted pairs with various air gaps of the insulation system stressed by the Square and Square-rising waveforms up to 30 kHz are modeled using COMSOL software.</p>

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Section: Numerical Modeling Of Electric Field Distribution In Twisted Pair Samplesupporting

confidence: 80%

Section: Numerical Modeling Of Electric Field Distribution In Twisted Pair Samplementioning

confidence: 60%

Section: Numerical Modeling Of Electric Field Distribution In Twisted Pair Samplementioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Modeling of high frequency high voltage of waveforms on life of enamel insulation

Rao¹,

Kasinathan²

2021

IJEECS

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“…Also, some of these materials as well as other resins can be used in the Vacuum Pressure Impregnation (VPI)process which can help eliminate/fill potential air voids in the machine/insulation system. Epoxy-mica, groundwall thickness= 3.04 mm [61] Excitation: 2 to 10 kV peak-to-peak @3kHz…”

Section: B Wind Generatormentioning

confidence: 99%

Survey of Insulation Systems in Electrical Machines

Hemmati

El-Refaie

2019

2019 IEEE International Electric Machines &Amp; Drives Conference (IEMDC)

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Insulating materials and insulation systems design have been gaining more attentions as more electrical machines tend to operate in harsher environments for various applications. Harsh environments include high temperature, humidity, erosion, low air pressure, etc. This paper discusses recent advances in insulation systems for electrical machines. Insulation tests as well as test standards that have been used to evaluate insulation systems and detect insulation failures will be discussed. Insulating materials used for a wide range of industrial applications such as wind turbine generators, aerospace hybrid/electric powertrain, and hydro generators have been summarized. For the emerging high-altitude, highvoltage aerospace applications, partial discharge and its impact on insulation systems will be discussed. Finally, polymer nanocomposite materials with excellent thermal conductivity and dielectric strength are highlighted as an outlook. SECTION I. Introduction Due to the continued growth of renewable energys, the number of electrical machines used worldwide has significantly increased. Insulation system is a very critical component of electrical machines. Insulation breakdown can lead to failures, which eventually result unpredicted downtime and negative financial impacts and in some applications can be a safety hazard. For some specific industries where uninterruptible operation is required, the unpredicted downtime is unacceptable. The unpredicted downtime for an offshore oil plant would be $25,000/h [1]. The dielectric strength of electrical insulation materials has been gradually improved over the years. By introducing new materials in the past 20 years for instance, the dielectric strength of ground-wall insulation nearly doubled [2]. Electrical, mechanical, thermal, and ambient stresses can cause insulation degradation which consequently leads to insulation failure [3], [4]. Insulation failure causes short circuits in the stator winding and consequently high currents could pass through the defected stator winding [5]. A survey on 1141 induction motors with power ratings above 200 hp shows that around 30% of motor failures are due to insulation failures [6]. With advances in sensors, digital signal processing, diagnosis methods and test standards, insulation failures can be detected [7], [8]. Through online estimation of material degradation and lifetime in early stages, insulation systems of electric machines can be protected from further aging while unpredicted downtime could be avoided through scheduled maintenance. Even though insulation system is a passive component in an electrical machine which does not produce torque, insulation build/thickness (which represents the key thermal resistance in electrical machine)can have significant impact on the machine cooling and hence electrical loading and torque production. There have been several efforts to minimize insulation thickness for design compactness, low manufacturing cost and high efficiency [3]. The two main functions of insulation systems in electr...

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