• Electrical & Electronic Materials
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• v.4 no.3
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• pp.229-238
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• 1991

본 논문에서는 영상센서를 이용하여 유기절연물질내의 트리 열화현상을 측정할 수 있는 시스템에 관하여 논하였다. 기존의 육안관찰법으로서는 관측하는 것이 매우 어려웠던 트리형상의 변화를 화상처리 기술을 이용하므로서 트리발생 직후부터 관측할 수 있게 되었다. 실험결과, 화상처리장치는 최초로 발생된 트리에서 부터 그 진전상황을 즉각적으로 기록할 수가 있었으며 트리의 신장도, 열화면적 및 연속 화상처리 측면에서 트리의 진전특성을 고찰하였다.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.1
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• pp.57-62
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• 1994

In this paper, a system for measuring of treeing degradation in organic dielectric material by using image processing technics, is discussed. Traditionally, treeing is measured by visual method. It made difficulty to understanding for features and changes in the configlEation of the tree growth. Using image processing system, it is made to describe the characters of the tree growth, specially length of tree and area of treeing degradation. From this image processing and visual measurement, the similar results were made, an automatic measurement system was made for configuration of the tree growth.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.11a
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• pp.201-204
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• 2000

전기트리근 절연체의 제작상태 및 운용중의 열화진단 방법으로 널리 연구되고 있다. 이러한, 전기트리 영상을 측정할 때는 일반적으로 트리패턴을 추출하는 과정을 사용한다. 하지만, 트리열화 과정의 재현성이 떨어지고 트리의 패턴이 복잡함으로 기존의 시각적 관측으로는 트리성장의 정확한 정량화가 어렵기 때문에 영상처리에 의한 실시간 처리가 제안되고 있다. 따라서, 본 연구에서는 측정된 전기트리 영상을 고주파 강화필터링과 이진화 과정 등을 거쳐 최적의 분석영상으로 변환한 후, 개선된 에지검출 기법을 이용해 전기트리 영상을 분석함으로써, 트리의 실시간 계측 및 정량화, 부분방전의 패턴인식, 측정결과를 통한 절연재료의 파괴 정도를 예측할 수 있었다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.2
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• pp.75-80
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• 2006

In this paper, to detect and observation the void discharges pulse signal, AE signals and tree growth characteristics in case the high voltage is applied to a XLPE sample for a power cable. We also examined the partial discharge current pulse and AE signals with the increase of the applied voltage in XLPE insulation. The experimental results show that a branch-type tree grows in the presence of the voids, and a bush-type tree grows in the absence of the voids in both samples. A rate of tree growth increases abruptly in proportional to the deterioration time in the presence of the of the voids, but in the absence of the voids, a rate of tree growth decreases as time goes by and finally a breakdown occurs. The frequency band of AE signals that are generated from the partial discharges in a XLPE sample, one of solid dielectric materials, is about 1.0[MHz].

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2000.11a
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• pp.301-306
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• 2000

케이블 절연파괴 사고에 관한 여러 통계에서 사고원인을 검토하여 보면, 전기트리, 열화, 침수의 순서로 발생하였으며, 전기트리에 의한 사고가 60%이상을 차지하고 있다［1］. 전기트리에 관한 억제책으로는 제조공정상의 개선, 블렌드 또는 공중합체를 이용하는 방법 또는 첨가제를 혼합하여 특성을 개선시키는 방법 등이 있다. 공정상의 개선은 어느 정도 한계에 이르렀으며, 공중합체를 만드는 것은 반응기를 수정해야 하는 어려움이 따라 활발하게 이용되지 못하고 있다.(중략)

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.6
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• pp.50-56
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• 1997

As the purpose of the breakdown prediction of three degradation of insulating materials caused by partial discharge occurring at various defects in the polymer insulator itself and at the interfaces between electrodes and the insulating materials. Treeing due to partial discharge os one of the main causes of breakdown of the insulating materials. Recently, the necessity of establishing the way to diagnoses the aging of insulation materials and to predict of insulation breakdown become improtant. The purpose of our work are to use acoustic emission System and fractal dimension and to investigated the treeing phenomena in polymeric insulation under appliec AC voltage 11[kV] with an artificial needleshaped void(1.5[mm]) using the above system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.3
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• pp.73-81
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• 1999

Measurements of ultrasonic signals caused by partial discharges were perlonnrl by using an ultrasonic measurement technique to diagnose the electrical treeing deterioration in an epoxy mold-type power transformer. We also examined the characteristics of tree growth, partial discharge magnitude and ultrasonic pulse number with the increase of the deterioration time. From these results, it was found that the shape of the tree was a branch-type, and the rates of the tree growth were examined when ac voltages of 16[kV] and 20[kV] were applied Ultrasonic pulse number and discharge magnitude were rapidly increased as the length of the tree grows after the middle stage of the deterioration time, and it appeared that ultrasonic pulse number was proportional to discharge magnitude. Attenuation, time-delaying and directivity characteristics of ultrasonic signals propagated into epoxy resin by using ultrasonic oscillation and receiving systems are also re[prted as a basic data of ultrasonic mesasurements in mold-type power transformer.former.

• Korean Journal of Materials Research
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• v.9 no.4
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• pp.398-403
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• 1999

Studies on the electrical treeing deterioration and dielectric breakdown phenomena in the polymeric insulator of polyethylene and epoxy resin were carried out. Block type samples with needle-plane electrode geometry were electrically stressed and the tree pattern from the needle tip was observed. In LDPE the density of electrical tree was very high and its pattern was bush type. For the case of XLPE, branched tree was observed. As temperature and SN content increased, the dielectric breakdown voltage decreased and the treeing phenomena became more complicated. Fan type cracks were observed around the conducting tree path in the brittle DGEBA/MDA system.

• Journal of the Korean Society of Safety
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• v.14 no.1
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• pp.216-221
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• 1999

The correlation between propagation of electrical tree and internal partial discharges is discussed. We use specimens with needle-plane electrode system made of LDPE(Low Density Polyethylene), observed inception and propagation of electrical tree by optical microscope and investigated the characteristics of the partial discharge (PD) pulses accompanying with propagation of electrical tree. In the specimens with needle-shaped void, the tree propagates branch type. The length of the tree has good linear relation with average discharge power of PD pulses. In the specimens without needle-shaped void, the tree grows bush type tree. The correlation between the area of the tree and the average discharge power of PD pulses has linear relation.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1587-1589
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• 1999

초고압 XLPE(가교 폴리에틸렌) 절연 케이블의 절연사고를 방지하기 위해서는 여러열화 조건하에서 절연체의 수명을 예측하는 것과 아울러 절연체(XLPE)의 성능향상을 모색하는 것이 바람직하다. 이러한 노력의 일환으로 절연재료의 열화현상을 화학반응의 법칙으로 가정한 Arhenius 모델과 같은 열화이론이 확립되어지고 있다 하지만, 실제 케이블을 만드는 과정에서 절연체의 성형 조건에 따른 절연 성능 평가와 관련된 연구는 그렇게 많지 않다. 본 연구에서는 XLPE의 성형 조건(가교, 건조, 냉각)에 따른 화학적 물성의 변화와 절연성능 사이의 상관관계를 알아보기 위해 LDPE에 가교제(DCP)를 첨가한 컴파운드를 이용해 만든 몰드 시편의 물성을 DSC, 가교도 분석 및 전기 트리 개시 전압을 측정해 살펴보았다. 그 결과 가교나 건조 조건에 비해 냉각 조건에 따른 가교 폴리에틸렌의 결정화도가 트리 개시전압에 보다 큰 영향을 미침을 알 수 있었다.