• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1968-1970
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• 2005

송전 용량 증대 및 초고압 케이블 컴펙트화를 위해, 최근 고내력 케이블에 관한 연구가 전세계적으로 활발히 진행되고 있으며, 이러한 추세에 대응코자 당사에서는 고내력 케이블 개발에 있어서 첨가제 투입에 따른 절연 능력 향상에 관한 연구를 진행하여왔다. 본 연구에서는 케이블 절연 능력 향상을 위하여 반도전 컴파운드에 첨가제를 투입하여 반도전과 절연의 계면 특성을 향상시킴으로 절연체의 절연파괴능력 향상시키고자 하였으며, 계면 특성의 향상은 절연 파괴능력 향상으로 이어짐을 확인 할 수 있었다. 또한 상기의 연구결과에 따라 제조된 케이블은 기존 케이블과 비교하였을 때 매우 우수한 절연파괴 특성을 나타냄을 확인하였으며, 그 결과 절연 두께를 비약적으로 감소시킬 수 있었다. 본 논문은 상기 절연 성능 향상에 관한 메커니즘 및 IEC 62067에 따라 진행된 초고압 XLPE 케이블의 type test 결과를 중심으로 기술하였다.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.1
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• pp.11-15
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• 2019

Recently, the circuit-breaker rated voltage is getting higher as the transmission voltage increases. To increase the circuit-breaker rated voltage, a multi-break circuit-breaker which has two or more breakers in series is adopted. For multi-break circuit-breaker, a grading capacitor is used to mitigate the Transient Recovery Voltage(TRV) and control the voltage distribution across the individual interrupter units. However, all over the world, there are many failures such as mechanical damage, explosion due to insulation breakdown. Therefore, it is necessary to study the causes of failure and the new performance verification method. In this paper, we investigate the causes of dielectric breakdown of the grading capacitors in the KEPCO power system and propose the performance verification method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.1
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• pp.22-29
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• 2000

This paper deals with the dielectric characteristics of $SF_6$ gas gap stressed by $\pm$1.2/44[$mutextrm{s}$] non-oscillating impulse and $\pm$0.4[$mutextrm{s}$]/1.14[MHz] oscillating impulse voltages in the presence of a needle-shape metallic particle in gas-insulated switchgear(GIS). Breakdown voltage-time (V-t) and breakdown voltage-gas pressure (V-p) characteristics were investigated and discussed. The experiments were carried out under highly inhomogeneous field geometry with a needle protrusion whose length and radius are 10[mm] and 0.5[mm], respectively. The gas pressure ranges from 0.1 to 0.5[㎫]. As a result, it was found that the electrical breakdown for both the positive and negative polarity develops with steplike pulses in leader mechanism, When subjected to the positive oscillating impulse voltage, the minimum breakdown voltages appeared in all the gas pressure ranges and the V-t curves have a pronounced upturning at short times to breakdown and give a little dependence of the gas pressure. On the other hand, in the case of the negative polarity the dependence of the V-t and V-p characteristics on the wave shape of the applied voltages is known to be appreciable.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.2 s.35
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• pp.167-174
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• 2005

Smaller size and higher integration of electronic components make smaller gap between metal conducting layers in electronic package. Under harsh environmental conditions (high temperature/humidity), electronic component respond to applied voltages by electrochemically ionization of metal and metal filament formation, which lead to short failure and this phenomenon is termed electrochemical migration(ECM). In this work, printed circuit board(PCB) is used for determination of ECM characteristics. Copper leads of PCB are soldered by eutectic solder alloys. Insulation breakdown time is measured at $85^{\circ}C,\;85{\%}RH$. CAF is the main mechanism of ECM at PCB. Pb is more susceptible to CAF rather than Sn, which corresponds well to the corrosion resistance of solder materials in aqueous environment. Polarization tests in chloride or chloride-free solutions fur pure metal and eutectic solder alloys are performed to understand ECM characteristics. Lifetime results show well defined log-normal distribution which resulted in biased voltage factor(n=2) by voltage scaling. Details on migration mechanism and lifetime statistics will be presented and discussed.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.6
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• pp.618-629
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• 2001

This paper presents a result of failure analysis and reliability evaluation for high voltage ceramic capacitors. The failure modes and failure mechanisms were studied in two ways in order to estimate component life and failure rate. The causes of failure mechanisms for zero resistance phenomena under withstanding voltage test in high voltage ceramic capacitors molded by epoxy resin were studied by establishing an effective root cause failure analysis. Particular emphasis was placed on breakdown phenomena at the ceramic-epoxy interface. The validity of the results in this study was confirmed by the results of accelerated testing. Thermal cycling test for high voltage ceramic capacitor mounted on a magnetron were implemented. Delamination between ceramic and epoxy, which might cause electrical short in underlying circuitry, can occur during curing or thermal cycle. The results can be conveniently used to quickly identify defective lots, determine $B_{10}$ life estimation each lot at the level of inspection, and detect major changes in the vendors processes. Also, the condition for dielectric breakdown was investigated for the estimation of failure rate with load-strength interference model.

• Electrical & Electronic Materials
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• v.8 no.5
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• pp.551-557
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• 1995

For the observation of treeing, a visual measurement with an optical microscope has been used to explain breakdown mechanism in high-voltage systems. The conventional directed visual method of tree aging observation is difficult to measure in short time processing, and it is impossible to analyze on tree degradation area, progressed direction, tree pattern, etc. By using an image processing technique, the tree features which appear immediately after the tree initiation as well as changes in the configuration of the tree can be easily measured and observed than using the conventional visual methods. In this paper, we have developed a tree observating system by using image processing for tree growth, degradation area and other treeing progress. As an experimental result, it can be concluded that the image processing method is a more effective alternative than directed visual observation method. As a matter of fact, it is possible to record the image of tree propagation immediately after its first appearance and explain the characteristics of tree growth froth the computer processing image.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.1
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• pp.35-43
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• 2002

In the last decade, considerable efforts have been made to make a new class of solid state high power, high speed electronic device, namely, the Photo-Conductive Power Switch(PCPS), and to characterize the high-field performance of PCPS under high power, high voltage conditions. But the problem of surface flashover phenomena persist, preventing the realization of reliable and efficient high-speed, high voltage switching devices. It is essential to have a clear understanding on the physical processes behind the surface flashover problem to develop new technologies and device architectures so as to fabricate PCPS that are capable of high-field high-voltage. Also, it is imperative to identify new materials that could satisfy the requirements for high-field, high-power devices. Since surface flashover, surface breakdown phenomena is observed for all the devices that foiled at the applied field much lower than semiconductor bulk breakdown field, surface passivation is considered one of the important practical methods to improve the high field performance of the devices. Therefore, this paper was studied the main properties and mechanism of the semiconductor surface flashover before and after passivation under high electric-field.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.4
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• pp.87-95
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• 1999

A primary limitation of the awlication of New class of solid state high power, high speed electronic device, narrely, the Photo-Conductive Power Switch(PCPS) is that the switches flashover at the surlace under average awlied fields much less than the bulk breakdown field of the semiconductor in most cases. The only way overcome those problffi1 and has a workable compact solid state switch is to passivate the surlace by a solid state dielectric material. In this experirrentation, The voltage withstands of Silicon is to be severely degraded when operated in vacuum(10[kV/cm]) and the perlormance is improved when operated in air(30[kV/cm[), in SF6(80~100[kV/cm]). After the passivation, the device had a breakdown field in vacuum and air at a field as high as the unpassivated device in SF6. A experirrent results show passivated devices have excellent breakdown field. In this paper, We improved the main properties and mechanism of the silicon breakdown before and after passivation under high field. field.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.1
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• pp.43-49
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• 2015

By the trends of electronic package to be smaller, thinner and more integrative, organic printed circuit board is required to be finer Cu trace pitch. This paper reports on a study of failure mechanism for PCB with fine Cu trace pitch using biased HAST. In weibull analysis of the biased HAST lifetime, it is found that the acceleration factor (AF) of between $135^{\circ}C/90%RH/3.3V$ and $130^{\circ}C/85%RH/3.3V$ is 2.079. A focused ion beam (FIB) was used to polish the cross sections to reveal details of the microstructure of the failure mode. It is found that $Cu_xO/Cu(OH)_2$ colloids and Cu dendrites were formed at anode (+) and at cathode (-), respectively. Thus, this gives the evidence that Cu dendrites formed at cathode by $Cu^{2+}$ ion migration lead to a short failure between a pair of Cu nets.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.2
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• pp.28-33
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• 2007

In this paper, we are studied on the direction and formation of carbonized conductive path according to surface leakage current between electrodes. The characteristics of the tracking as surface is broken down between exposed live parts. Using the HSIS(high speed imaging system. 100,000[fps], redlake ltd., USA), it took photographs by arc growth mechanism occurred in on/off surge, ground fault and discharge between electrodes. Then the results was analyzed. Hereafter, it expected effects that application of energy utility technology through the arc control.