Partial discharge-induced degradation characteristics of insulating materials of gas-filled power transformers

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

doi:10.1109/tdei.2010.5658221

Cited by 10 publications

(6 citation statements)

References 6 publications

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“…In particular, this kind of measurement provides useful information on the operating state assessment of cables, joints, terminations, and other components installed in high voltage systems [ 1 ]. Considering the degrading effect of the PDs phenomena [ 2 ], if they are detected on time, the breakdown of service of the entire medium/high voltage system can be avoided. For this reason, PD monitoring of electrical apparatuses during normal operating conditions is a great solution to avoid disservices and to increase the reliability of power systems.…”

Section: Introductionmentioning

confidence: 99%

Partial Discharge Detection Using a Spherical Electromagnetic Sensor

Romano

Imburgia

Ala

2019

Sensors

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The presence of a partial discharge phenomenon in an electrical apparatus is a warning signal that could determine the failure of the insulation system, terminating the service of the apparatus and/or the network. In this paper, an innovative partial discharge (PD) measurement instrument based on an antenna sensor is presented and analyzed. Being non-intrusive is one of the most relevant features of the sensor. The frequency response of the antenna sensor and the features to recognize different PD sources and automatically synchronize them with the supply voltage are described and discussed in details. The results show the performance of the instrument can make a fast and correct diagnosis of the health state of insulation systems.

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Section: Introductionmentioning

confidence: 99%

Partial Discharge Detection Using a Spherical Electromagnetic Sensor

Romano

Imburgia

Ala

2019

Sensors

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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%

“…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%

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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“…To address these issues, the authors have used insulating materials themselves and element models simulating insulating structures of gas-filled transformers to evaluate a harmful PD and establish the harmful limit at a material level [7,8]. In the test using an actual transformer, this PD is measured from outside at the bushing test terminal or the neutral point terminal, or by connecting a coupling capacitor if no bushing test terminal is available [3][4][5].…”

Section: Gas-filled Power Transformers Became Commerciallymentioning

confidence: 99%

“…There is a case that the transmission rate is lower than 1% depending on the pulse injection position. However, when reflecting the operating conditions of an actual transformer that the only voltage equivalent to that for one turn is applied to the adjacent turn, no PD is actually considered to occur between turns [7,8].…”

Section: Simulating Pulse Injected Between Turnsmentioning

confidence: 99%

Partial discharge signal propagation characteristics inside the winding of gas-filled power transformer - experimental study using winding models in the air

Okabe

Ueta

Wada

2011

IEEE Trans. Dielect. Electr. Insul.

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To establish clear control criteria for a partial discharge (PD) test of long duration ac withstand voltage test of a gas-filled power transformer, the authors have conducted a study on the harmful PD level of materials themselves using the insulating material-and structuralmodels of an actual gas-filled power transformer. In the PD test on an actual transformer, since the PD having occurred inside the transformer is measured from the outside, the measured signal is damped due to various influential factors, such as the position of occurrence, measurement position, and internal structure of the equipment. In particular, in the event of the PD between sections or turns, which might actually occur, significant damping of the signal is anticipated in certain cases due to the influence of the position of occurrence and the internal structure of the equipment, which is a propagation path. Therefore, this damping must be taken into consideration to establish control criteria for the PD. In this paper, to understand the characteristics of this damping, such as its magnitude, two types of winding, interleaved disk and continuous disk, were produced as transformer models to investigate the propagation characteristics of PD signals with the position of occurrence, measurement position, and wavefront duration of the PD as parameters. Consequently, it emerged that, where the PD occurs between sections or turns, the transmission rate at the measurement position was generally low because the PD signal circulates within the PD occurrence parts and does not come outside. Assuming measurement at the bushing test terminal, the lowest transmission rate was 2.8% and 2.0% between sections and turns, respectively. A study was also conducted on the occurrence of the PD against ground, despite the low anticipated potential of actual occurrence, and the lowest transmission rate was 4.0%. Accordingly, the PD having occurred inside the winding of the transformer can be detected with a magnitude of 2% or more; however, from a reverse perspective, the signal is detected as one significantly damped to a level of about 1/50. Index Terms -Gas-filled power transformer, partial discharge (PD), pulse propagation characteristics, transmission rate, interleaved disk winding, continuous disk winding, ERA.

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Partial discharge-induced degradation characteristics of insulating materials of gas-filled power transformers

Cited by 10 publications

References 6 publications

Partial Discharge Detection Using a Spherical Electromagnetic Sensor

Partial Discharge Detection Using a Spherical Electromagnetic Sensor

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

Partial discharge signal propagation characteristics inside the winding of gas-filled power transformer - experimental study using winding models in the air

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