• Electrical & Electronic Materials
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• v.7 no.1
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• pp.42-48
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• 1994

The preventive diagnosis technique for power system is being highlighted as a research area for deterioration of insulation in machinery because of high-voltage power system. We make efforts to develop not only diagnosis of aging state but also detection of defects in the initial stage from preventive diagnosis technique. Especially, partial discharge is actively studied as a non-destructive diagnosis technique and very useful because partial discharge measurement reduces damage than conventional diagnosis technique. The loaded stress during this test is smaller than that of other diagnosis techniques. But the continuous research for various complicated analysis method is required because partial discharge has very small signals and its signals have complex forms. In this paper, the measurement of partial discharge was investigated and studied on many specimens with void. We made samples having artificial voids and measured partial discharge. In order to use as a practical diagnosis technique, we studied ways of measurement, measured illustrations and types of partial discharge which could be used in order to diagnose defects of power machinery.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.1
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• pp.75-81
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• 2018

In this study, the simulation of partial discharge pulse waveform have been performed for the typical joints such as EBA and PMJ in the HV underground transmission XLPE cable system in order to improve the understanding of partial discharge pulse waveform and the on-site measurement accuracy of partial discharges. FDTD simulation technique was adopted for the simulation and has been shown to be suitable for partial discharge simulation of power cables in terms of pulse propagation characteristics and waveform formation. The simulation results for the EBA showed that the second not-so-large opposite polarity peak appeared after the first negative polarity peak and the measurement sensitivity was the highest near the bottom of the EBA copper box. In the analysis results for PMJ, the magnitude of the second opposite polarity peak was large enough to compare with the first peak, and the measurement sensitivity at the end of the PMJ copper box was the highest. These simulation results show considerable similarity with the on-site measurement, and it would be very useful for the partial discharge measurement of HV XLPE cable systems.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1936-1938
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• 2004

In this paper, we discussed measurement method of PD (Partial Discharge) of 22.9[kV] cable. Cable rail track laying portable detector that can detect partial discharge of cable connection ashes by on-line done spot way to detect Lemke equipment and high broadcasting CT sensor that use antenna sensor using ICM mounting was explained. Because measurement corona signal is very big, analysis of partial discharge is difficult state, we used connector. It could be attenuated by 2 times. We found out that corona signal which generated on B phase is flowed on A phase and C phase. It could measure that partial discharge of A phase happens actually. We could confirm that partial discharge of about 250 ${\sim}$ 300 [pC] on A phase is dangerous.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.134-138
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• 1994

According to request of insulating materials for high-voltage, recently we make effort not only to develop diagnostic skills of aging state but also to discover defects in insulating material in the early. Especially, partial discharge has been actively studied as a non-destructive diagnosis technique and very useful method. Because the method of partial discharge measurement has damages less than other conventional diagnosis technique. In this paper, the characteristics of partial discharge was investigated and studied on many samples with voids. In order to adapt as a practical diagnosis technique, it is studied on the characteristics of partial discharge and insulation breakdown in the high voltage. We suggest that partial discharge measurement can be used in order to diagnose defects in high-voltage insulation materials.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.4
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• pp.247-252
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• 1999

In this paper, in order to investigate availability of the OW-PD measurement method which has been proposed as an alternative of AC-PD measurement method to an after laying test and/or diagnosis for the power cable system, partial discharges owing to the needle-type defect integrated into the cable have been measured using AC and OW(Oscillating Wave) voltages. In the AC-PD measurement, the magnitude, phase and pulse number of partial discharges have been changed with the duration of voltage application, which can be analyzed through the relation with the process of the electrical tree initiation and propagation. In addition, the characteristics of partial discharges using OW voltage are appeared to be similar to those in case of AC-PD measurement and to be different with the shapes of electrical tree. From these results, it is concluded that the OW-PD measurement method is available to the tests for the cable system.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.2
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• pp.294-300
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• 1996

In hydro-generator, a groundwall insulation of stator windings gradually deteriorates due to mechanical, thermal, electrical and environmental stresses. These stresses combine to result in loose windings, delamination of the stator insulation and/or electrical tracking of the endwinding, all of which can lead to stator insulation failures. Conventionally, off-line tests such as partial discharge measurement, DC/AC current and .DELTA.tan.delta. tests has been used for estimation of winding condition. However, off-line test requires large power supply and generator outage. In addition, major cause of insulation problems such as loose wedges and slot dischages may not be found with off-line diagnoses. This paper introduces the on-line partial discharge measurement techniques using frequency spectrum analyzer(FSA) for the generator stator windings. The experimental results from the UIAM #1 hydro-generator confirms a optimistic application of on-line generator diagnosis method as a reliable tool for evaluation of winding condition.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.10
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• pp.960-964
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• 2005

In this paper, we dealt with a partial discharge(PD) measurement method that has been accepted as an effective and non-destructive technique to estimate insulation performance of low-voltage electric and electronic devices. The PD measurement system Is composed of a coupling network, a low noise amplifier, and associated electronics. h shielded box Is adopted to make a better measurement environment against around noise. A low cut-off frequency of the coupling network estimated by a sinusoidal wave input was 125 kHz (-3 dB). Calibration tests on laboratory set-up have shown that the PD measurement system has a stable sensitivity of 10 mV/pC. In an application test oil a low-voltage three phase Induction motor (5 HP), we could detect 0.53 pC level of partial discharge at the applied voltage of AC 650 $V_{peak}$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1784-1789
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• 2009

This paper describes the measurement technology of the dissolved hydrogen gas due to partial discharge in oil using gas sensor. For higher resolution and less error in measurement of the dissolved hydrogen gas in oil, the sensor outputs with ambient temperature which affect the sensor output characteristics should be considered. The sensor output trends with ambient temperature and the properties of the dissolved hydrogen gas in oil with partial discharge characteristic were analyzed through the test results. It was indicated that the sensor peak and the base voltage with measuring time were affected by ambient temperature and the measurement errors of the sensor output by temperature were reduced by using the difference between the peak and the base voltage rather than just the peak voltage. In addition, the hydrogen gas sensor outputs were increased with the increase of partial discharge energy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.451-455
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• 1997

The partial discharge has been blown as the chief breakdown of power equipments. The analysis and the recognition is much difficult because the partial discharge signal is very small and has complex aging pattern. Recently, insulation aging diagnosis based on pattern of phase(Ф), partial discharge magnitude(q), number(n) has been very important. Owing to depreciate the reappearance of aging progress at the electrical tree pattern and to be difficult to analyze visually, the study on partial discharge pattern is suggested to normalizing analysis method of partial discharge signals. This parer is purposed on prediction of life-time measurement of cv-cable, on decision of risk degree with normalization and real-time measurement of partial discharge signals for aging diagnosis of cv-cable. As normalizing the aging signals of electrical tree in cv-cable, it is able to confirm risk degree of insulation material with the distribution of Ф-q-n and recognize the process of aging pattern using neural network.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.208-211
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• 2005

This paper presents an ultra-low partial discharge(PD) measurement system that has been accepted as a non-destructive method to estimate electrical insulation of low-voltage electric devices. The PD measurement system is composed of a coupling network, a low noise amplifier, and associated electronics. A shielding box is used to make a better condition against electromagnetic interference. A low cut-off frequency of the coupling network was 1MHz(-3 dB). Calibration tests on laboratory set-up have shown that the PD measurement system has a stable sensitivity of 11.4mV/pC. In an application experiment on a low-voltage induction motor(5HP), we could detect 0.77pC level of partial discharge pulse at the applied voltage of AC 664 V$_{peak}$.