• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.120-120
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• 2010

To detect the PD events, we have studied a fusion sensor, the UHF sensor and the single-walled carbon nanotube(SWNT) gas sensor. We are accustomed to the UHF sensor which have employed to detect the partial discharges in apparatus GIS-like. But the SWNT gas sense is a newly way proposed to detect the partial discharges. In this study, we monitored not only the changes of the electrical conductance of the SWNT sensors in responding to the PD events but also the signal of the UHF sensor at the same time with IEC 60270 standard method for reference on the partial discharge events.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.867-872
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• 2005

This paper describes the measurement and location method of partial discharges in high voltage CV cables. Coupling capacitors were used to detect partial discharge signal. Impedance characteristic of the coupling circuit and an amplifier with a high Common Mode Rejection Ratio(CMRR) were studied to improve sensitivity of the circuit. From the calibration experiment, the sensitivity of the partial discharge detection circuit was about 100pC. Also, we confirmed that the location of partial discharges in cables can be estimated by calculation of time difference between the first pulse and the second one reflected from the other end of the cable.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.4
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• pp.172-177
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• 2006

During normal machine operation, partial discharge(PD) tests were performed with partial discharge analyzer(PDA) in two hydrogenerators. Six cable couplers were installed in circuit ring bus and endwinding of three phases. PDA showed that the normalized quantity number(NQN) and the partial discharge magnitude$(Q_m)$ were very low in hydrogenerator #1 and #2, respectively. The trend analyses of NQN and $Q_m$ value are available for monitoring of the insulation condition in hydrogenerator stator windings. The insulation condition of stator winding can be assessed. Discharge at conductor surface was discovered in B phase(C2 coupler) of hydrogenerator #1. Internal discharges were generated in A and C phases(C2 coupler) of hydrogenerator #1 and in A, Band C phases(C1 and C2 couplers) of hydrogenerator #2. Slot discharges occurred in A, Band C phases(C1 coupler) of hydrogenerator #1. The stator windings of two hydrogenerators were in good condition.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.5
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• pp.80-85
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• 1997

Preventive diagnosis technique of power transforms is very important for highly reliable operation of power systems, and especially that of online transformer is needed in view of economy. Acoustic methods for partial discharge points have been studied abroad since 1960's in earnest. Electric-ultrasonic locating method by which partial discharges are found through detecting the electric and ultrasonic signal generated in partial discharge and ultrasonic-ultrasonic locating method by which partial discharges are found through detecting two ultrasonic signal with two ultrasonic sensor have been researched in our country. By using this ultrasonic-ultrasonic locating method, it was proposed of graphical determination technique of partial discharge points one dimension, two dimension, three dimension. But in locating partial discharges, they have assumed that the number of signal origin is one. So in this study we suggests a method of locating and knowing the number of signal origins when there are several origins by using ultrasonic-ultrasonic method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.2
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• pp.251-256
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• 2012

This study deals with the location of partial discharges(PDs) for power cables and GIS using 2 PD sensors and long coaxial signal cables. Throughout the experiments by use of simulated PD pulses and corona discharges in the power cable system, it is found out that the impedance matching between the coaxial signal cable and the measuring equipment should be done for good S/N ratio and the on-site measurement using more than 100m-long coaxial signal cable is possible. In addition, new PD location algorithm with the polarities of PD pulses and the arrival time difference between two pulses was proposed and was proved through the partial discharge experiments for the cable joint defect and artificial void defect.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.4
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• pp.183-188
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• 2006

Abstract - In order to investigate the possibility of separating PD(partial discharge) and noises through the pulse analysis by use of a HFCT, pulse shapes measured by a resistive sensor and a HFCT were analyzed and adequate PA(pulse analysis) algorithms were studied. For the purpose, the HFPD detection and PA system has been developed. Also void discharges and air corona were adopted as the artificial defect and noises, respectively. As a result, it is possible to separate partial discharges and noises through the PA method using the $100kHz{\sim}20MHz$ frequency range HFCT. It is expected to apply the developed system to on-site PD measurements for the electric equipments.

• 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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• 1988.11a
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• pp.252-257
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• 1988

This paper discribes an improved technique for locating partial discharge sites within operating transformers by ultrasonic method which utilizes the different travel times of the electrical and ultrasonic signals produced by partial discharges to determine the location of the sources. The technique was to develope the measurement system based on the enhancement of the acoustic emission signals using signal square, circuit to improve the detectable sensitivity and reliability. Also an ultrasonic pulse generator was designed and made to transmit periodically pulses equivalent to pratial discharges and to check the good performance of the system, echo effects and self-diagnosis. Through the laboratory work, it was confirmed that the system and the generator can be used satisfactorily for diagnosing power transformers and for studying echo effects and self-diagnosis of the system.

• Transactions on Electrical and Electronic Materials
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• v.10 no.5
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• pp.173-176
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• 2009

In the stator windings of a 6.6 kV rotating machine, internal discharges, slot discharges, and surface discharges are mainly caused by internal voids and insulation degradation. If a partial discharge(PD) occurs in an inner-part of the stator windings, it will cause electromagnetic pulses with wide frequency ranges. Discharge sparks and electromagnetic pulses generated from a discharge source, can be detected using various RF resonators like an EM sensor. In order to detect these types of electromagnetic sources, a planar patch sensor was designed and fabricated using a CST-MWS simulation, and PD signals from an artificially defected stator winding were also measured by the sensor proposed in this study. Furthermore, an HFCT was used as a reference sensor and compared with the proposed new planar patch sensor. In the results of the experiment, the planar patch sensor showed a similar performance to the HFCT sensor.

• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.559-565
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• 2008

This study designed a new type of loop antenna that is able to detect partial discharges based on microstrip line technology. In the diagnosis of power cables, partial discharge signals are generally produced at a frequency range less than 100MHz because high frequency PD signals are lost along a propagation path in such cables. The new type of loop antenna sensor has been studied using simulation software known as CST microwave studio version 5.0. In partial discharge measurement experiments, a commercial HFCT sensor was used as a reference sensor. Several experiments were made over HFCT and loop antenna sensors for detecting partial discharges on 22.9kV MV XLPE cable. In this study, we showed the loop antenna designed in this study that can be applied as a commercial HFCT sensor.