Investigation of the effect of repetitive voltage surges on epoxy insulation

Stone, G.C.; Heeswijk, R. G. van; Bartnikas, R.

doi:10.1109/60.182659

Cited by 52 publications

(16 citation statements)

References 13 publications

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“…However, a transient surge voltage induced by the switching of IGBTs has been considered as a critical issue for electrical insulation of motor windings. Partial discharge (PD) activities in motor windings due to the surge voltage have been identified as one of the main factors of insulation failures of inverter-fed motors [1,2]. Major research effort is now being devoted to the above problem from both sides of suppression of surge voltage and improvement of insulation properties of motor windings.…”

Section: Introductionmentioning

confidence: 99%

Effects of ambient humidity and temperature on partial discharge characteristics of conventional and nanocomposite enameled magnet wires

Kikuchi

Murata

Uozumi

et al. 2008

IEEE Trans. Dielect. Electr. Insul.

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Effects of ambient humidity and temperature on partial discharge (PD) characteristics in twisted pairs with conventional and nanocomposite enameled magnet wires have been investigated. Measurements of the PD inception voltage (PDIV) and the apparent PD charge were performed by applying an ac sinusoidal waveform voltage of 60 Hz to the twisted pair. The observed PDIV in this study can be classified into the following three behaviors. First, the PDIV in both wires decreases with increasing relative humidity (RH) at low temperature. Secondly, the PDIV in both wires slightly increases when increasing the RH at high temperature. Thus, there is a certain value of the absolute humidity to determine the lowest PDIV in both cases with the conventional and nanocomposite enameled wires. Thirdly, the PDIV in the conventional enameled wire significantly decreases at the RH of 95 %, while the decrease rate of that in the nanocomposite enameled wire is relatively small. The observed PD phenomena are discussed in terms of material characterization of the enameled wires such as changes in permittivity due to moisture absorption and wettabilitiy under voltage application.

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Section: Introductionmentioning

confidence: 99%

Effects of ambient humidity and temperature on partial discharge characteristics of conventional and nanocomposite enameled magnet wires

Kikuchi

Murata

Uozumi

et al. 2008

IEEE Trans. Dielect. Electr. Insul.

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“…Although natural UV radiation itself can cause photoionization, it is insignificant to the overall degradation of the insulation system compared to effects from electrical discharges [7], [8]. Use of corona-imaging instrument sensitive to UV radiation eliminates the need for complete darkness during quality control inspection.…”

Section: Introductionmentioning

confidence: 99%

Black-Out Test Versus UV Camera for Corona Inspection of HV Motor Stator Endwindings

Stranges

Haq

Dunn

2014

IEEE Trans. on Ind. Applicat.

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As part of a factory acceptance test program for highvoltage (HV) motors, end users sometimes specify a black-out test. This is a traditional offline inspection where the stator is placed in complete darkness, each phase is energized to 115% of rated line-to-neutral voltage, and both ends of the stator are observed to determine the presence, location, and severity of endwinding surface partial discharges (PDs). The setup for the test may be complex and risky due to the need for observers to be standing in darkness close to the energized parts of the stator. The test results are qualitative and strongly depend on the observer's eyesight and individual perception. A safer and more accurate alternative is to use an ultraviolet (UV) camera or viewer. The observed PD activity may be observed in ambient lighting, recorded, and quantified through simultaneous offline PD measurements. This paper describes the two inspection techniques and presents experimental validation of the UV corona camera inspection method as a suitable replacement for a black-out test. Sample 13.8-kV coils were wound in a fixture simulating their relationship in a stator winding and subjected to high-potential tests while observed under black-out conditions and with a UV corona camera in ambient lighting. The stator windings from two HV compressor motors were inspected using the same camera. Recorded images of the observed discharges and measured PD activity in the sample coils and stator winding were used to compare the evaluation by each test method.

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“…Voltage surges are known to be one of the factors leading to tracking failure [8]. So far most research data on maintenance and protection relate to atmospheric pressure, but in most cases, this data can not be extrapolated for application to low pressure environments [9].…”

Section: Introductionmentioning

confidence: 99%

Effects of low pressure on tracking failure of printed circuit boards

Liu

2008

IEEE Trans. Dielect. Electr. Insul.

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In general, printed circuit boards (PCBs) used in power devices and system operation in low pressure environments are more susceptible to damage from surface discharges. Additionally, repetitive operation of power systems is an important factor leading to tracking failure. Whether the tracking phenomenon at low pressures is different from that at atmospheric pressure needs better understanding to ensure reliable applications. In this paper, studies of tracking failure of PCBs in a low-pressure chamber, are reported for an electrode configuration comprising a pointed end of track close to the side of a track. Test samples were made by printing these tracks onto a glass-cloth epoxy-resin laminate. Experiments were carried out using repetitive unipolar pulses to simulate voltage surges. The ambient pressure was reduced from atmospheric pressure to a very low pressure (0.6 kPa). The time to failure and the cumulative charge passing before failure were recorded as function of the pressure, temperature, pulse interval and insulation distance. The results obtained indicate that the low pressure enhances the breakdown endurance of PCBs and the breakdown phenomena at low pressure are different from those at atmospheric pressure. With the decrease of the pressure, the cumulative charge is increased but the tracking failure is delayed. At low pressures, increasing temperature has little effect on the cumulative charge, but has significant influence on the time to tracking failure.

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Investigation of the effect of repetitive voltage surges on epoxy insulation

Cited by 52 publications

References 13 publications

Effects of ambient humidity and temperature on partial discharge characteristics of conventional and nanocomposite enameled magnet wires

Effects of ambient humidity and temperature on partial discharge characteristics of conventional and nanocomposite enameled magnet wires

Black-Out Test Versus UV Camera for Corona Inspection of HV Motor Stator Endwindings

Effects of low pressure on tracking failure of printed circuit boards

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