The voltage endurance of cast epoxy resins

Studniarz, S. A.; Dakin, T. W.

doi:10.1109/eic.1978.7463635

Cited by 31 publications

(7 citation statements)

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“…This fact can be removed by introducing a threshold value, as shown in Figure 2, and various models of electric aging are therefore adjusted. Modified equations of the power model [9] and the exponential model [13] are shown in Equations (10) and (11), respectively.…”

Section: Electrical Aging Modelsmentioning

confidence: 99%

“…However, a more concrete model of aging can be designed when all degradation processes are fully understood. Certain degradation factors acting in a concrete EIS can be identified, such as electric field intensity [10][11][12][13], temperature [14][15][16][17], mechanical stress [18], radiation [19], moisture [20], dust [21], chemical stress [22], etc. and including these degradation mechanisms into a single model would be impossible.…”

Section: Introductionmentioning

confidence: 99%

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Proposal of Physical-Statistical Model of Thermal Aging Respecting Threshold Value

Soucek¹,

Trnka

Hornak

2017

Energies

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Abstract:The aging of electrical insulation material or a system is a main issue for designers of high-voltage (HV) machines. Precise determination of the life cycle of electrical insulation is one way of improving the efficiency of electrical machines involved in the production and transmission of electrical energy. Much effort has been devoted to preparing statistical or physical methods of Electrical Insulating System (EIS) life time estimation in the real operation of electrical machinery. The main aim of this paper is to introduce a new physical-statistical model of thermal aging respecting the threshold value. This model is based on thermal aging model and the main difference between this model and previously published models is taking into account the threshold value of degradation factor. The complete design of this model is presented in this paper, including functions defining the threshold value of the effect of the degradation factor depending on the temperature. Proposed model was verified by accelerated thermal aging test at selected temperatures (160, 170, 180 • C) and time intervals (0, 120, 240 h) on a commonly used transformer board. The breakdown voltage was set as an indicating parameter of the level of thermal aging and was measured according to standard IEC 60243-1. Collected data from these measurements were used for threshold value determination (431.23 K) and verification of proposed physical-statistical model of thermal aging respecting the threshold value.

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Section: Electrical Aging Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Proposal of Physical-Statistical Model of Thermal Aging Respecting Threshold Value

Soucek¹,

Trnka

Hornak

2017

Energies

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“…A method to accelerate degradation by increasing the frequency of the applied voltage (frequency acceleration test) is known as an effective means of determining the long-term degradation characteristics of insulators [6,[16][17][18]. This frequency acceleration test is used to verify the long-term reliability of various insulating materials as well as investigating the development process of a defect inside insulators.…”

Section: Introductionmentioning

confidence: 99%

“…To address this issue, various studies on epoxy insulators, mainly used for GIS spacers [1][2][3][4][5][6][7][8][9], were conducted. It was subsequently reported that the insulation of epoxy insulators with no defect did not decline, even if they were exposed to an electric field (EF) more than twice as high as GIS operating EF for 30 years [3].…”

Section: Introductionmentioning

confidence: 99%

Insulation characteristics of epoxy insulator with internal crack-shaped micro-defects - study on the equivalence of accelerated degradation by frequency acceleration test

Ueta

Wada

Okabe

et al. 2014

IEEE Trans. Dielect. Electr. Insul.

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Generally, insulating spacers of gas insulated switchgear (GIS) have outstanding durability and are not considered prone to insulation failure within a design life of about 30 years, provided the products conform and have passed the partial discharge (PD) test. However, to assume operation over 30 years, degradation characteristics are important in cases where an extremely microscopic defect below the detection level in the PD test is present or produced inside the insulator. Accordingly, to date, the authors have obtained the breakdown voltagetime (V-t) characteristics using epoxy insulators provided with three types of micro-defect (crack, void, and delamination); the apparent PD of which is equivalent to 1 pC for an actual 550 kV-GIS spacer. It emerged based on these V-t characteristics that the breakdown risk peaked for a crack defect among those three types of shape and that it was essential to obtain data on long-term breakdown characteristics at the actual operating electric field level to rigorously evaluate the breakdown risk under long-term operation. Therefore, this paper includes a study on the equivalence of accelerated degradation by frequency acceleration as a means of determining the long-term breakdown characteristics. In the study, the dependency of various PD characteristics on frequency was initially examined by changing the frequency of the applied voltage within the range 60 to 3000 Hz. Consequently, the increase in the number of PDs per unit time proportional to frequency could be confirmed without any abnormal phenomena, such as suspended discharge, observed within the frequency range this time. In other words, it was clarified that the degradation due to PD could be accelerated by increasing the frequency. Subsequently, breakdown tests were conducted with frequency as a parameter to evaluate the frequency up to which the equivalence of accelerated degradation could be maintained based on breakdown times. As a result, it was found that the equivalence of acceleration degradation by frequency acceleration was valid in acceleration at up to 1500 Hz because the breakdown time was shortened in reverse proportion to the frequency.Index Terms -Gas insulated switchgear (GIS), epoxy insulator, micro-defect, crack, partial discharge (PD), breakdown voltage -time (V-t) characteristics.

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“…A life model has been presented later by Dakin et. al according to the electric aging experiment formula and thermal aging experiment formula [6]:…”

Section: Introductionmentioning

confidence: 99%

Effect of breakdown strength and space charge distribution in polyimide/TiO<inf>2</inf> nanohybrid films aged by corona treatment

Zha

2009

2009 IEEE 9th International Conference on the Properties and Applications of Dielectric Materials

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Polyimide/Tifr-(PI/Ti0 2 ) nanohybrid films containing surface modified nano-Ti0 2 by employing silane coupling agent (KH550) were prepared by using in-situ dispersive polymerization process. The space charge distribution, electrical aging and other dielectric properties in both pure PI films and PI/Ti0 2 nanohybrid films were investigated. Space charge in the nanohybrid films was measured with pulsed electro-acoustic method (PEA). Results showed that the nano-Ti0 2 particles have made a prominent effect on the process of dielectric breakdown, lifetime and space charge behavior. The incorporation of nano-Ti0 2 increased the voltage endurance significantly. We discovered the space charge were greatly decreased and field distribution trended to uniform in the nanohybrid films with the concentrition of Ti0 2 was 10 wt.%. The relation of space charge distribution with the concentration of nano-Ti0 2 and the aging time was explored. The relative mechanism of the electrical field distributions which distorted by space charges in samples was also discussed.

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The voltage endurance of cast epoxy resins

Cited by 31 publications

References 0 publications

Proposal of Physical-Statistical Model of Thermal Aging Respecting Threshold Value

Proposal of Physical-Statistical Model of Thermal Aging Respecting Threshold Value

Insulation characteristics of epoxy insulator with internal crack-shaped micro-defects - study on the equivalence of accelerated degradation by frequency acceleration test

Effect of breakdown strength and space charge distribution in polyimide/TiO<inf>2</inf> nanohybrid films aged by corona treatment

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