• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.467-469
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• 2001

This paper presents an efficient location estimation methodology for a partial discharge(PD) source in the power transformer. The methodology previously proposed is not suitable for locating a PD source because the ultrasonic signal with medium attenuated through the inner structure. In general, the propagation characteristic of ultrasonic signal with medium is different. Therefore, using this propagation characteristic, we can detect the location of PD source. In this paper, the proposal algorithm finds the PD source using three sensors attached to one side of the transformer without attenuation of the ultrasonic signal and applying the neural network based geometrical method. The proposed methodology demonstrates the effectiveness and validity on an experimental transformer.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.301-306
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• 2008

Various sensors such as capacitive probe, high frequency current transformer (HFCT), and acoustic emission (AE) probe were applied to a cast resin dry type transformer for partial discharge detection. We designed and fabricated a wideband low-noise amplifier having a gain of 40[dB]. From the experiment which was carried out in the same transformer, the sensitivities were 7.16[mV/pC] for capacitive probe, 3.8[mV/pC] for HFCT, and 17.9[mV/pC] for AE probe.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1909-1911
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• 2000

Recently many research activities on the diagnosis of stator winding insulation of large rotating machines have been reported. Capacitive couplers are widely used as sensors for on-line partial discharge (PD) measurement of high voltage rotating machines. This paper presents laboratory test to compare Stator Slot Coupler (SSC), Resistance Temperature Detector (RTD), 80 [pF] coupler and 500 [pF] coupler for on-line PD measurement of rotating machines.

• Proceedings of the KIEE Conference
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• 2007.04b
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• pp.169-171
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• 2007

We studied the partial discharge detecting by sensing electromagnetic wave emitted from the partial discharge source in the HV Rotating Machine with the new prototype patch antenna sensor. In this study, we design new type of patch antenna based on microstrip technology and make many experiments of elaine testing compare with the existing HFCT and EM probe on stator winding of HV generator in the laboratory. This paper will mention comparison of experimental results based on the three kinds of sensors.

• Journal of Electrical Engineering and information Science
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• v.1 no.2
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• pp.45-51
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• 1996

This paper presents a neural network approach for on-line estimation of partial discharge(PD) location using advanced correlation technique in power transformer. Ultrasonic sensors detect ultrasonic signals generated by a PD and the proposed method calculates time difference between the ultrasonic signals at each sensor pair using the cross-correlation technique applied by moving average and the Hamming window. The neural network takes distance difference as inputs converted from time difference, and estimates the PD location. Case studies showed that the proposed method using advanced correlation technique and a neural network estimated the PD location better than conventional methods.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1604-1605
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• 2011

This paper deals with the partial discharge detection in order to recognize with three different nature of artificial defects using non-conventional HF-VHF PD sensor of which two measuring position are chosen along the 22.9kV XLPE power cable specimen. The response of the sensor under investigation has been observed be significantly affected by the cable length from the PD sources. As a result, it seems that the detecting sensor position is very important for the analysis of the nature of PD source. Moreover, it could be suggested that any standardized calibration method should be established replacing IEC 60270 as far as any type of non-conventional sensors are concerned.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.1
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• pp.53-60
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• 2010

This paper dealt with the acoustic detection of partial discharge (PD) in insulation oil for insulation diagnostics of oil immersed transformers. Electrode systems such as needle to plane, plane to plane, and floating were fabricated to simulate some defects in transformers. A wide band acoustic emission(AE) sensor with the frequency ranges of 100 kHz~1 MHz and a narrow band AE sensor with the resonant frequency of 140 kHz were used in the experiment. Also, a decoupler and an amplifier were designed to detect and amplify the acoustic signal only. The decoupler separates acoustic signal from DC source without any distortion, and the amplifier has the gain of 40 dB in frequency ranges of 11 kHz~4 MHz. In the experiment, frequency components and propagation characteristics of acoustic signal were analyzed, and an algorithm of positioning of PD occurrence by the time difference of arrival was proposed. From the results, the frequency components of the acoustic signal exist from 50 kHz to 200 kHz and the positioning error of PD calculated by three AE sensors was within 1%.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.6
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• pp.324-329
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• 2004

Six stator slot couplers(SSC) and a flux probe sensor installed on the stator winding slots of large turbine generator. Assessment of insulation condition has been based upon the measurements of partial discharge(PD) of stator windings and shorted-turn of rotor windings in operating large turbine generator. The maximum PD magnitude(Qm), normalized quantify number(NQN), PD pattern and shorted-turn were measured using on-line insulation condition monitoring system. The NQN and Qm of slot PD side in the phase A are indicated the highest value in six SSC sensors. Monitoring system results showed that discharge at conductor surface and internal discharge were detected at the surface of stator winding and in voids of the groundwall insulation. Insulation of stator and rotor windings in large turbine generator was judged to be in good condition.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2265-2267
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• 2005

We present detailed studies of externally applicable UHF PD sensors for a metal covered epoxy barrier with a small opening of epoxy injection-hole. The sensors were attached at the surface of injection hole of a metal covered epoxy barrier. 3-Dimensional electro magnetic simulations were performed to analyze electric-field distribution of the GIS and epoxy barrier with injection hole. Sensor structures were designed and analyzed using the 3-D EM simulator then fabricated for experimental verification. Sensor performance was measured in terms of spectral response and detected peak power. Real scale GIS and epoxy barriers were used to test and measure various aspect of performance of the sensors.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2000.11a
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• pp.89-93
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• 2000

Recently many research activities on the diagnosis of stator winding insulation of large rotating machines have been reported. Capacitive couplers are widely used as sensors for on-line partial discharge (PD) measurement of high voltage rotating machines. This paper presents laboratory test to compare Stator Slot Coupler (SSC), Resistance Temperature Detector (RTD), 80 [pF] coupler and 500 [pF] coupler for on-line PD measurement of rotating machines. And a novel on-line monitoring system for an insulation diagnosis is proposed.