Partial discharge-induced degradation characteristics of oil-impregnated insulating material used in oil-immersed power transformers

Okabe, Shigemitsu; Ueta, Genyo; Wada, H.; Ōkubo, H.

doi:10.1109/tdei.2010.5539694

Cited by 22 publications

(15 citation statements)

References 5 publications

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“…In order to investigate the degradation characteristics of the main insulation of a transformer caused by PD, the element model was degraded in the PD exposure test and a residual LI withstand voltage test [6][7][8] was conducted following exposure to PD. Figure 4 and the experimental conditions are shown in Table 1.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Subsequently, the applied voltage was adjusted so that the PD magnitude could be a specified value and then that voltage was maintained for a specified duration. The duration of time for which the voltage was applied was set as 1 hour as the standard, based on the results of tests previously conducted using the PB materials themselves [6]. In the test using the PB materials themselves, since the insulation degradation was observed when the PD magnitude was 20,000 pC or more, the test was also conducted for 2 hours in the case of 20,000 pC.…”

Section: Exposure To Partial Discharge the Pd Test Setup Is Shown Inmentioning

confidence: 99%

“…For the PB, the breakdown voltage (BDV) is estimated according to equation (1). In the test previously conducted using the PB material itself [6], the breakdown voltage of new PB 0.8 mm thick was 100 kV. Therefore, the value of V 0 can be set to V 0 =100/0.8 0.8 =120 kV.…”

Section: Evaluation Of Harmful Partial Discharge Level In Residual LImentioning

confidence: 99%

“…As the first step of the study for this purpose, the previous paper [6] investigated the PD magnitude and the insulation damage level of the oil-impregnated PB used between windings, at which PD is more likely to occur when ac voltage is applied than any other oil-impregnated insulating paper material used in transformers, and studied the harmful PD level. To investigate the harmful PD level for the actual transformer, the present study uses an element model that simulates the insulating structure of the oil-immersed transformer and quantitatively evaluates the relationship of the magnitude and duration of PDs [6][7][8] with the degradation of insulators using the decrease rate of the lightning impulse (LI) breakdown voltage.…”

Section: Introductionmentioning

confidence: 99%

“…To investigate the harmful PD level for the actual transformer, the present study uses an element model that simulates the insulating structure of the oil-immersed transformer and quantitatively evaluates the relationship of the magnitude and duration of PDs [6][7][8] with the degradation of insulators using the decrease rate of the lightning impulse (LI) breakdown voltage. The insulating structure between windings was simulated by the element model and the mixingin of metallic particles was assumed in order to investigate the PD magnitude and the insulation damage level and study on the harmful PD level.…”

Section: Introductionmentioning

confidence: 99%

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Partial discharge-induced degradation characteristics of insulating structure constituting oil-immersed power transformers

Okabe

Ueta

Wada

et al. 2010

IEEE Trans. Dielect. Electr. Insul.

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The soundness of an oil-immersed power transformer under an operating voltage is evaluated in partial discharge (PD) test of long-duration ac withstand voltage test. The acceptance criterion for this PD test is 500 pC according to IEC standard; however, only insufficient basic data backing this criterion are available. In addition, the harmful level of the insulation performance has not necessarily been perceived in such a manner as the present one, for example, only the insulation breakdown, instead of the insulation performance degradation, has been assumed to be harmful. In light of the consideration presently paid, it is necessary to determine the PD level that causes the insulation performance to be degraded in order to confirm the soundness by the test using an actual transformer. As the initial step of the study for this purpose, the previous paper investigated the PD and the insulation damage level using oil-impregnated press-boards (PBs) used in the transformer, at which PD is more likely to occur when ac voltage is applied than at any other parts, and evaluated the harmful PD level for insulating materials themselves. To investigate the harmful PD level for the actual transformer, this paper studied the harmful PD level that decreases the residual lightning impulse (LI) withstand voltage using the main insulation model, which is the insulating structure constituting the oil-immersed power transformer. As a result, black discoloration occurred on the surface of the PB and the residual LI withstand voltage also tended to decline when exposed to ac PD of 20,000 pC or more. On the other hand, when it had been exposed to ac PD of 10,000 pC, no visible damage was observed and there was no drop in the residual LI withstand voltage either. Consequently, the harmful ac PD level for the oil-immersed transformer can be determined at between 10,000 pC and 20,000 pC. This result coincided with that for insulating materials themselves, hence it was revealed that the harmful PD level be set to 10,000 pC on a conservative side.Index Terms -Oil-immersed power transformer, partial discharge (PD), press-board (PB), insulating element model, residual lightning impulse withstand voltage, harmful partial discharge level, and insulation degradation.

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Exposure To Partial Discharge the Pd Test Setup Is Shown Inmentioning

confidence: 99%

Section: Evaluation Of Harmful Partial Discharge Level In Residual LImentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Partial discharge-induced degradation characteristics of insulating structure constituting oil-immersed power transformers

Okabe

Ueta

Wada

et al. 2010

IEEE Trans. Dielect. Electr. Insul.

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Application of a combined decision model based on optimal weights in incipient faults diagnosis for power transformer

Tingfang

Zhang

et al. 2016

IEEJ Transactions Elec Engng

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A new method for the diagnosis of incipient transformer faults based on a combined decision model using IEC 60599 three-ratio method, grey system theory (GS) algorithm, Dempster-Shafer evidence (DS) theory, and backpropagation (BP) neural network diagnosis method is proposed in this paper. The new method will eliminate the influence of any one individual diagnosis method due to insufficient information or diagnostic prejudices. In order to minimize the sum-of-squared errors of the proposed method, the optimal weights of every individual method which comprises the combined decision model are calculated based on their own diagnosis error ratios. Thus a combined decision model based on optimal weights (CDMOW) is formed. Then the optimal diagnosis result is obtained based on CDMOW. Results of diagnosis instances show that the use of CDMOW not only gives a much higher diagnostic accuracy rate but also more stability in fault diagnosis than any single method composing it.

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Statistical analysis of induced magnetic fields on oil-impregnated insulation pressboards

et al. 2020

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Partial discharge-induced degradation characteristics of oil-impregnated insulating material used in oil-immersed power transformers

Cited by 22 publications

References 5 publications

Partial discharge-induced degradation characteristics of insulating structure constituting oil-immersed power transformers

Partial discharge-induced degradation characteristics of insulating structure constituting oil-immersed power transformers

Application of a combined decision model based on optimal weights in incipient faults diagnosis for power transformer

Statistical analysis of induced magnetic fields on oil-impregnated insulation pressboards

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