• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권6호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1285-1287
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• 2003

The aging of the insulation reduces the electrical and mechanical strength of the insulation. At same point, a voltage surge or mechanical shock from a traction motor start will fracture or break down the insulation. To achieve the expected life usually requires extensive laboratory evaluation of the insulation systems and the use of accelerated aging tests. There are several nondestructive test available for checking. the condition of motor insulation, the probable extent of aging, and the rate of which aging is taking place. So the insulation characteristics of stator coil were each analyzed by measurement of dielectric loss($tan{\delta}$), capacitance and partial discharge. The method of diagnosis is able to analyze the aging condition and predict the life of the traction motor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.231-235
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• 2001

Insulation aging diagnosis system provides early warning regarding electrical equipment defect. Early warning is very important in that it can avoid great losses resulting from unexpected shutdown of the production line. Since relations of insulation aging and partial discharge dynamics are non-linear, it is very difficult to provide early warning in an electrical equipment. In this paper, we propose the design method of insulation aging diagnosis system that use a magnetic wave and acoustic signal to diagnoses an electrical equipment. Proposed system measures the partial discharge on-line from DAS(Data Acquisition System) and acquires 2D Patterns from analyzing it. For fettering the noise contained in sensor signals we used ICA algorithms. Using this data design of the neuro-fuzzy model that diagnoses an electrical equipment is investigated. Validity of the new method is asserted by numerical simulation.

• 한국화재소방학회논문지
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• 제14권1호
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• pp.1-7
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• 2000

절연재료의 내부에서 부분방전이 발생하면 국부파괴와 완전절연파괴의 원인이 된다. 부분방전으로 생기는 트리잉은 절연재료를 열화시키고 절연 수명을 단축시키는 중요한 원인이 된다. 따라서 절연파괴의 예측과 절연재료의 수명을 진단할 수 있는 방법에 대한 연구는 매우 중요하다. 고전압 하에서 일어나는 트리잉 현상에 대해서 저밀도 폴리에틸렌의 트리잉 개시 전압과 그 진전 과정을 진성파괴의 견해에서 고찰하였다. 이러한 관점에서 본 연구는 고전압하에서 일어나는 트리잉현상에 대해서 저밀도폴리에틸렌에서 트리형상의 전계의존성에 관하여 고찰하였다. 결과로서 트리의 성장을 그 내부가 각각 유전체 혹은 도체라고 가정했을 때의 중간적인 특성을 갖는다는 추리하에 이론적으로 검토한 결과, 실험결과와도 잘 일치됨을 알 수 있었다.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권1호
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• pp.10-14
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• 2003

The occurrence of partial discharge (PD) in solid dielectrics is very harmful because it leads to the deterioration of insulation by electrical, chemical, and thermal reactions as a combined action of the discharged ions bombarding the surface and by the action of chemical compounds that are formed by the discharge. Consequently, if any defects are present in the solid insulation system, performance decreases until the system breaks down. Therefore, removing or suppressing the defect is very important. Voids are a typical defect in the solid insulation system and are very harmful because they deteriorate insulation. As a basic step, studying the properties of PD in voids is important because an accurate knowledge of these properties is required to estimate the deterioration of voids. In this paper, the correlation between the size of voids and internal PD is discussed as a function of the time of the applied voltage and its magnitude. Magnitude, repetition rate, average discharge power, and average discharge current of PD in specimens with large voids were found to be larger than the others in this experiment. The smaller specimens had voids when the magnitude and number of PDs were reduced.

• Transactions on Electrical and Electronic Materials
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• 제3권3호
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• pp.34-38
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• 2002

In this paper, efficiency estimation of toxicity fee fire resistance cable experiments was measured smoke density of toxicity free fire resistance polyolefin insulation material and electric field dependence of tree shape in low density polyethylene (LDPE). One of the most serious causes of failure in high-voltage cables, can be an electrical discharge across an internal gab or void in the insulating material. Treeing due to partial discharge is one of the main causes of breakdown in the insulating materials and reduction of the insulation life. Therefore the necessity for establishing a method to diagnose the aging of insulation materials and to predict the breakdown of insulation and research of the fire resistance character has become important. First, we have studied on electric field dependence of tree shape in LDPE about treeing phenomena occurring on the high electrical field. Second, the measurement method is the attenuation quantity of irradiation by smoke accumulating with in a closed chamber due to non-flaming heat decomposition and flaming combustion. A main cause of fire-growth and generating toxic gas when, it bums, should be dealt with great care in life. safety design. The fire gases were occurred carbon monoxide and decomposition than in polyolefin due to incomplete combustion of PVC, which has high content of carbon in chemical compound.

• 조명전기설비학회논문지
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• 제22권5호
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• pp.7-12
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• 2008

부싱의 형상에 따라 전계 분포를 비교하여 가장 효율적인 형상을 설계하고자 하였다. 본 연구에서 형상 변화는 12 조건이며 전극 길이의 변화로 벡터 분포도는 0.7[%], 전계 분포도는 약 $21{\sim}26[%]$의 절연 성능을 향상시킬 수 있었다. 그리고 고압부 절연물 두께의 변화는 벡터 분포도는 2[%], 전계 분포도는 약 $23{\sim}43[%]$의 절연 성능을 향상시킬 수 있었다. 따라서 조건변화에 따라 절연성능이 향상되는 것을 알 수 있으므로 부분방전 개시전압 소멸전압을 향상시킬 수 있을 것으로 사료된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1299-1303
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• 1995

The detection and measurement of partial discharge activity prevalent in the solid insulating systems of high-voltage generator stator windings has, for many years, been a recognized method of assessing the insulation condition of such systems. Partial discharge activity occurs at sites of degradation within, or at the surface of, stator's insulation systems under high voltage stressing. However, partial discharge pulses suffer from attenuation and distortion when transmitted along windings, because of the complex L-C network between windings. The mode of transmission varies with the signal frequency and is dependant on the geometrical configurations of windings. This paper reports the investigated results of the signal propagation characteristics along the windings when both sinusoidal signals and simulated partial discharge pulses are injected at the various positions of stator windings within the 25 MVA, 11 kV hydro generator. The on-line identification technique of partial discharge location in generator windings is also proposed in this study.

• 한국전기전자재료학회논문지
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• 제31권4호
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• pp.255-260
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• 2018

In recent years, increasing electricity use has led to considerable interest in green energy. In order to effectively supply, cut off, and operate an electric power system, many electric power facilities such as gas insulation switch (GIS), cable, and large substation facilities with higher densities are being developed to meet demand. However, because of the increased use of aging electric power facilities, safety problems are emerging. Electromagnetic wave and leakage current detection are mainly used as sensing methods to detect live-line partial discharges. Although electromagnetic sensors are excellent at providing an initial diagnosis and very reliable, it is difficult to precisely determine the fault point, while leakage current sensors require a connection to the ground line and are very vulnerable to line noise. The partial discharge characteristic in particular is accompanied by statistical irregularity, and it has been reported that proper statistical processing of data is very important. Therefore, in this paper, we present the results of analyzing ${\Phi}-q-n$ cluster distributions of partial discharge characteristics by using K-means clustering to develop an expert partial discharge diagnosis system generated in a GIS facility.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2001년도 학술대회논문집
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• pp.145-149
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• 2001

The most of faults in gas insulation of power facilities are caused by partial discharge. Therefore we simulated partial discharge and measured the radiated electromagnetic wave emitted from partial discharge in SF$_{6}$ gas by biconical antenna. This paper describes time delay and electric fields pulse characteristics of radiated electromagnetic waves with distance(1[m], 3[m], 5[m]) between antenna and discharge source.e.