• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 A
• /
• pp.118-120
• /
• 1996

We've been reported recently that increase of installing big power converting equipment which makes harmonics result in damage on transformer for incoming and load. Specially, harmonics that cause overheat and aging is severer in cast-resin transformer a kind of dr type than in oil one. The goal of this paper is to prove the process for aging of transformer that result from harmonics in according to both of theory and actual measurement on site. And we introduce diagnostic methods to estimate aging condition of cast-resin transformer in accordance with simulation.

• 조명전기설비학회논문지
• /
• 제28권7호
• /
• pp.55-61
• /
• 2014

This paper presents a method to reduce the stray loss of core Tie-Plate of distribution power transformer. The method combines a 3-dimensional FEM with PSO(Particle Swarm Optimization) algorithm to determine the shape of the Tie-Plate that minimizes eddy current and flux-leakage losses. To verify the method a 24MVA distribution(cast-resin) transformer was simulated using one objective function and two design variables with some constraints. The final optimized Tie-Plate has nine($3{\times}3$) slots of 10mm width, 15mm thickness and 25mm distance. After four iterations, the Tie-Plate loss was reduced to about 21 % of the original.

• 전기학회논문지
• /
• 제65권11호
• /
• pp.1937-1942
• /
• 2016

Unlike oil immersed transformers, cast-resin transformers have the solid insulator 'epoxy resin' in sealed structure. Therefore, they reveal a lot of limitations in checking aging conditions and predicting an accident. This study analyzed the characteristics of Cast-resin transformers by the measurement distance and measurement sensitivity with a corona defect sample, using antenna sensor. Therefore, the experiment has proven that the antenna sensor-based measurement method proposed in this study is able to detect the insulation defect location of the cast-resin transformer, unlike conventional measurement methods. It is expected that the result of this study will be used to develop a new type of measuring method in order to measure insulation defects and to use in safety inspection of domestic cast-resin transformers.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 하계학술대회 논문집
• /
• pp.402-405
• /
• 2002

This paper presented the characteristic of Heat-transfer on the winding composed with Epoxy-resin in a 50 kVA cast-resin dry type transformer The resin cast transformer is used widely in supplying electricity systems. However, to know the thermal characteristics of that is very useful in designing, manufacturing, and maintaining, there is no pertinent method to calculate this. In this paper, Based on the results of the physical characteristics and the simulation by commercial software using FEM method, we established the Prototype Model for this. According to that Model, an analysis on a variation of the hottest spot temperature was discussed as a function of thermal conductivity for the individual windings composed with Epoxy-resin. The thermal conductivity of the individual windings with reference to upper way was discussed.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 C
• /
• pp.1936-1938
• /
• 2000

In this paper, a frequency spectra of AE (acoustic emission) signals detected from the partial discharges of an epoxy resin void and a cast resin transformer in operating were analyzed to offer the proper frequency range of AE signals from the corona discharge for the purpose of AE sensor selection, From these results, a frequency spectra of AE signals emitted from the corona discharges in the void of an epoxy resin sample were about 190[kHz] to 220[kHz] by the FFT(fast fourier transform), A frequency spectra of AE signals emitted from a cast. resin transformer with non-load were appeared to be downward of about 140[kHz] by the FFT, and then a frequency spectra of AE signals emitted from the above of cast resin transformer with load were appeared to increase from about 190[kHz] to 220[kHz] by the FFT.

• 조명전기설비학회논문지
• /
• 제16권3호
• /
• pp.47-54
• /
• 2002

본 논문은 단상 50[kVA] 몰드변압기 권선부의 열전달 특성에 대한 연구 결과이다. 1차 권선의 열전도도는 권선을 이루고 있는 물질 비 즉, 1차 권선의 절연을 담당하는 다량의 에폭시 수지와 그에 비해 소량의 구리 도선을 고려하여 결정하였다. 반면에 2차 권선의 경우 구성 성분은 다량의 구리도선과 절연을 담당하는 소량의 에폭시 수지로 되어 있다. 2차 권선 열전도도는 질량 비로서 결정될 수 없기 때문에 2차 권선의 열전도도값은 시작품의 측정 최고온도와 FEM을 이용한 분석결과를 비교하여 결정하였다. 각 권선부의 물리적 특징을 고려하여 상용 프로그램을 통해 시뮬레이션 모델을 만들었다. 본 연구결과를 바탕으로 몰드변압기 권선부에 Hole이 존재할 때와 안할 때 각각에 대해 주위온도·풍속변화에 따른 최고온도 변화를 고찰하였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 C
• /
• pp.1891-1893
• /
• 2000

In this paper, we studied the diagnostic technique to analyze the deterioration of cast resin transformer using partial discharge detection for on-site application.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
• /
• pp.444-447
• /
• 2003

All objects with some temperature above absolute zero radiate in the infrared. The intensity of the infrared radiated from a object defends on the condition and temperature on the surface of the one. The present, these techniques are frequently adopted into diagnosis for electricity equipments. Simply, however, the applied techniques are passive thermal testing for the detection of loosened terminals and overcurrent. In this paper, a infrared thermal imager was applied to high voltage windings of cast resin transformers, and the accumulated value of the result temperatures was used for evaluating remained lifetime of them. At each aging level, dielectric loss tangent test was carried out. The results offered capabilities for deciding the condition of the transformers suffering difficulties to diagnose.

• KIEE International Transactions on Electrophysics and Applications
• /
• 제5C권5호
• /
• pp.191-195
• /
• 2005

This paper presents an assessment method in integrity of the windings in cast resin molded transformers by using vertical analysis of thermal distribution. The proposed method is to compare the temperature distribution in a sound specimen with that in the faulted specimen with a layer to layer short circuit. Temperature distribution was acquired by an infrared thermography system, and the Arrhenius equation was adopted to the accelerated test. The proposed method can be used to detect the failures in the transformers.

• 한국전기전자재료학회논문지
• /
• 제22권9호
• /
• pp.786-791
• /
• 2009

Transformer failures are mostly due to partial discharges (PDs) caused by the deteriorated insulation. It is, therefore, important to monitor PD occurrence in insulation system and prevent their deterioration. The presented paper deals with a PD detection method by a capacitive probe, which easily apply to cast - resin dry - type transformers. The PD detection system consists of a capacitive probe and a low noise amplifier having the frequency bandwidth of 500 $Hz{\sim}30$ MHz. In the experimental set-up, sensitivity of the system is 7.16 mV/pC.