• 전기학회논문지P
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• 제59권3호
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• pp.311-316
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• 2010

According to increase of combined cycle power generation, the manufacturing market of gas turbine generator has become more competitive, so there is high pressure on the manufacturer to reduce generator price. Global VPI(vacuum pressure impregnation) method is effective to save the production cost and time for manufacturing stator windings, but it has an abrasion problem by vibration between stator windings and slots. This paper presents the insulation breakdown case, which is for VPI type generator during high voltage insulation tests, and also shows the cause analysis, repair works as well as reliability test. the purpose of this paper is to understand the insulation properties of VPI type generator and to know prevention of insulation weakness.

• Journal of Power Electronics
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• 제3권3호
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• pp.159-166
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• 2003

The winding insulation of low-voltage induction motors in adjustable-speed drive system with voltage-fed Inverters is substantially stressed due to the uneven voltage distribution and excessive voltage stress (dv/dt), which result in the premature insulation breakdown In this paper, the detailed insulation test results of 26 low-voltage induction motors are presented. Six different types of insulation techniques are applied to 26 motors. The insulation characteristics are analyzed with partial discharge, discharge inception voltage, AC current, and dissipation factor tests Also, insulation breakdown tests by high voltage pulses are performed, and the corresponding breakdown voltages obtained.

• KIEAE Journal
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• 제3권3호
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• pp.3-11
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• 2003

The purpose of this study is to develope an available outdoor insulation construction for the green roof system in Korea. On its own economical and structural problems of constructional risk, the typical outdoor insulation construction on the korean spot does not function efficiently with the green roof. Therefore, this study consists of four main contents as follows: 1. The objectives of the study are established by analysing the problems of the typical in- and outdoor roof insulation system in korea. 2. The foreign outdoor insulation systems for the green roof are clarified to find out an acceptable prototype for Korea. 3. According to loadtest, the prototype, which has a waterproof on the thermal insulation, is tested to demonstrate the structural safety. 4. The U-value test of the prototype on KS F 2277 brings the thermal performance of the green roof system, which can influence the thickness of the insulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.584-587
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• 1993

Mica, which have a good thermal and electrical characteristics, while will cleave easily at these layers. In order to bond mica materials soldily, mica/epoxy composite insulation materials were developed for generator stator winding. There are lots of problems such as delamination and partial discharge of these insulation materials caused by mechanical, electrical and thermal aging. Several experiments have been conducted in order to find the useful diagnostic parameters from the partial discharge phenomena by applying a new measurement techniques. this paper deals with the partial discharge pulse characteristics, which may be a useful diagnostic concept in predicting insulation condition of generator stator insulation materials. Long term insulation aging test shows that partial discharge phase angle an magnitude are identified as one of the main key techniques for insulation diagnosis on generator stator winding.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1603-1603
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• 2011

As time goes by these cables make a insulation problems, and ask for a preventive diagnosis method. Cable has very high electrostatic capacity and insulation defects mainly caused by water-tree(WT). Dissipation factor test is very useful for detecting WT but it needs huge power supply. In this paper we presented a cable insulation diagnosis by dissipation factor using low frequency power supply.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.195-198
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• 2000

In this paper the insulation characteristics test results of 25 low-voltage induction motors($3\phi$, 5HP, 380V) are presented. Five different types of insulation techniques are applied to 25 motors. The maximum partial discharge (PD) magnitude ($\textrm{Q}_{m}$) discharge inception voltage (DIV) dissipation factor tip-up ($\Delta$tan$\delta$) and rate of change in AC current($\Delta$I) are measured by PD and AC current tests. Also the insulation breakdown tests by high voltage pulse are performed and the corresponding breakdown voltage are obtained.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1706-1708
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• 2001

Nondestructive tests are used to evaluate the insulation condition of stator windings in rotating machine. These tests included ac current, tan delta and maximum partial discharge. The insulation condition of stator windings was assessed by three test items. The stator windings were generally in good condition, wash, reimpregnation and rewind. It was confirmed that nondestructive tests were most useful method to indicate the insulation condition of stator windings.

• Journal of Advanced Marine Engineering and Technology
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• 제38권1호
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• pp.99-104
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• 2014

본 논문에서는 탄화수소화재 조건에 따른 방화 댐퍼의 내화성능 평가에 대한 선행논문 실험체 -1(126 mm, $136^{\circ}C$)에 대하여 H-120 등급 방열성 확보가 가능한 최적의 코밍 방열 조건을 도출 하고자 노출면 코밍 방열 두께와 비 노출면 코밍 방열 길이 변화를 변수로 하여 내화실험을 수행 하였다. 내화실험 결과 실험체-2(88 mm, $171^{\circ}C$)는 H-120 방열성 허용기준을 만족하였으나, 실험체-3(50 mm, $185^{\circ}C$)은 110분에 방열성능 허용기준을 초과하는 것으로 나타나 실험체-2의 방열 조건이 실험체-1로부터 경량화가 가능한 최적의 방열 조건으로 확인 되었으며, 온도상승에 대한 비교결과 노출면 코밍 방열두께가 감소될 경우 방열재 표면온도는 격벽을 통한 전도열에 의한 영향 크며, 코밍 표면온도는 블레이드와 노출면 코밍으로부터 방사되는 복사열에 의한 영향이 큰 것으로 판단된다.

• 전기학회논문지
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• 제58권7호
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• pp.1375-1379
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• 2009

Insulation tests have been performed on two generator stator bars under accelerated aging under a laboratory environment. Electrical stress was applied to stator bar No.1, and electrical and thermal stresses were applied to stator bar No.2. Nondestructive stator insulation tests including the ac current, dissipation factor($tan{\delta}$), and partial discharge tests have been performed on both bars as the bars were aged for 11460 hours. Experimental test results show that ${\Delta}I$, ${\Delta}tan{\delta}$, and partial discharge of No. 1 and No.2 stator bars increased with increased in aging time. It has been concluded from the test that the stator insulation of the two generators are in good condition.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.100-100
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• 2010

Because of power consumption increase, global wanning, and limitation of installation, not only high reliability and interruption capability but also compact and light power apparatuses are needed. To improve the insulation performance, the high E field concentration phenomena was considered. Breakdown mechanism in vacuum is different from that in other insulation materials. therefore, It is necessary to understand the electric field distribution and insulation characteristics. This paper discusses the simulation and LI(light impulse) test of the shield of outside vacuum interrupter As a result, FEM simulation and LI test show that improve distribution of electrical field and equi-potential line. due to external shield. in this case, outside shield induced electric field of triple junction point.