• Title/Summary/Keyword: Transformer

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A Study on the Acoustic Detection of Partial Discharges in Insulation Oil (유중 부분방전의 음향검출에 관한 연구)

  • Kil, Gyung-Suk;Kim, Sung-Wook;Park, Dae-Won;Kim, Sun-Jae;Song, Jae-Man
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.1
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    • pp.53-60
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    • 2010
  • This paper dealt with the acoustic detection of partial discharge (PD) in insulation oil for insulation diagnostics of oil immersed transformers. Electrode systems such as needle to plane, plane to plane, and floating were fabricated to simulate some defects in transformers. A wide band acoustic emission(AE) sensor with the frequency ranges of 100 kHz~1 MHz and a narrow band AE sensor with the resonant frequency of 140 kHz were used in the experiment. Also, a decoupler and an amplifier were designed to detect and amplify the acoustic signal only. The decoupler separates acoustic signal from DC source without any distortion, and the amplifier has the gain of 40 dB in frequency ranges of 11 kHz~4 MHz. In the experiment, frequency components and propagation characteristics of acoustic signal were analyzed, and an algorithm of positioning of PD occurrence by the time difference of arrival was proposed. From the results, the frequency components of the acoustic signal exist from 50 kHz to 200 kHz and the positioning error of PD calculated by three AE sensors was within 1%.

A study on the life prolongation of pad mounted transformer through the improvement of heat radiation (지상변압기 방열 개선을 통한 수명연장에 관한 연구)

  • Chun, Sung-Nam;Park, Chul-Bae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.503-503
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    • 2007
  • 본 논문에서는 지중배전(22.9kV) 선로에 사용되는 지상변압기를 대상으로 수행한 방열해석 및 개선과 변압기수명연장에 관한 검토 결과를 수록하였다. 변압기의 열화메커니즘에 대한 문헌 조사를 통해 변압기 온도와 수명간의 관계를 작도하였는바, 수명 평가를 위한 핵심 인자로 열에 의한 절연지의 열화에 초점을 맞추었다. 기존 외함에 설치된 방열구중 상부 위치를 상부판에도 변경하는 경우 약25%의 통풍량 증가 효과를 기대할 수 있을 것으로 평가 되었으며 상부판과 내함 사이에 형성되던 고온 영역에서의 온도를 약$15^{\circ}C$정도 낮출 수 있는 것으로 나타났다. 절연지의 인장강도 변화로 평가한 수명예측 곡선에 따르면 약$10^{\circ}C$의 은도 저감은 약10배의 수명 연장 효과를 가져오는 것으로 나타난바, 본 연구에서 확인한 방열구의 위치 변경에 따른 지상기기 내부의 온도 저하는 변압기 수명을 연장하는데 일조할 것으로 기대된다. 기존 지상변압기에서의 방열구조를 통해 변압기 온도와 수명간의 관계를 작도하였는바, 수명 평가를 위한 핵심인자로 효과적으로 방열할 수 있는 새로운 외함의 구조 및 디자인을 제시하고 시뮬레이션을 통해 개선효과를 예측하였다. 또한, 개선된 모델을 가지고 실제 변압기를 제작한 후 부하를 인가하여 개선전과 후에 대한 방열효과를 실증시험을 통해 확인하였다.

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An Experimental Study on the Propagation Characteristics and Reduction of Impulse Noises from a High Voltage COS Fuse (고전압 COS 퓨즈로부터 방사된 충격성 소음의 전파특성과 저감에 관한 실험적 연구)

  • Song, Hwa-Young;Ju, Kyung-Min;Lee, Dong-Hoon;Kang, Rae-Goog;Jung, Nak-Hun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.71-74
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    • 2005
  • This experimental study describes the propagation characteristics and reduction of impulse noises emitted from a high voltage COS(Cut Out Switch) fuse of a transformer. When a high voltage COS fuse becomes a short circuit by the over current. The peak sound Pressure above 150dB(A) is generated. In this study, an impulse noise generator is designed for generating the impulse noises similar to the noise level of COS fuse, which is utilized to test the noise reduction of a reactive silencer. The reactive silencers have been tested for 10 different types with each different porosity, hole diameter and length. From the experimental results, it is found that the reactive silencer has an excellent performance to greatly suppress the impulse noise and that its performance is closely connected with the porosity and hole diameter.

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A study on an experimental basis a special character of insulating oil the use of a transformers (변압기용 절연유의 특성에 관한 실험적 연구)

  • Kim, Sung-Dae;Park, Il-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.11
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    • pp.5188-5193
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    • 2011
  • This research is for temperature control of insulating oil inside the transformer. After I designed and manufactured various systems using Peltier element, which was thermal element, and Heat pipe, which was a cooling system, without electric power. The optimum system could be made by applying them to the temperature control for the insulating oil. I could verify that the combination type of Heat pipe 100 W+ Peltier 100W has a more outstanding capacity than pure Heat pipe 300 W within 60 degrees Celsius through experiments. Through this, I verify that the method of a proper design is prominent, and make an attempt at contribution to power saving effect and more effective control of Distributing board by using this combination type.

A Study on the Characteristics Analysis of Automotive Ballast System (자동차 조명장치용 고압 방전등 시스템의 특성해석에 관한 연구)

  • Lee, Do-Ho;Kim, Byeong-Woo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.9
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    • pp.3795-3801
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    • 2011
  • The mathematical simulation of voltage and current waveform of the discharge lamp is useful for the analysis and design of ballasting circuits. This paper proposes a mathematical model which has lamp power and negative voltage drop in discharge lamp. Simulation applying the proposed model has been done, and the results are compared with the experimental results. Furthermore, in the paper, the ballast components(core, transformer) was designed such that high intensity discharge could be optimized for the automotive, by applying a method simulation based design.

The Implementation of Current Compensation Controller in Driving Voltage type Converter considering the Unbalance of Reactor at the Source Side (전원측 리액터 불평형을 고려한 전압형 컨버터의 전류 보상 제어기 구현)

  • Chun Ji-Yong;Cho Yu-Hwan;Lee Geun-Hong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.5 no.5
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    • pp.413-420
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    • 2004
  • In this paper, the control algorithm of DC source device for inverter starting is proposed and the control method for compensating unbalance system source on operating time in the voltage type PWM converter with driving and regenerative faculty is suggested. The maintaining method of balancing condition for converter of AC source is used the compensating unbalanced status by current control loop. In order to solve the problem which the unbalanced system control is used to leakage transformer not equaled reactance by each phase in rectifier system. The proposed H/W and control algorithm of rectifier system is contributed to minimize of device and rising efficiency.

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A New Dual-Active Soft-Switching Converter for an MTEM Electromagnetic Transmitter

  • Wang, Xuhong;Zhang, Yiming;Liu, Wei
    • Journal of Power Electronics
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    • v.17 no.6
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    • pp.1454-1468
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    • 2017
  • In this study, a new dual-active soft-switching converter is proposed to improve conversion efficiency and extend the load range for an MTEM electromagnetic transmitter in geological exploration. Unlike a conventional DC/DC converter, the proposed converter can operate in passive soft-switching, single-active soft-switching, or dual-active soft-switching modes depending on the change in load power. The main switches and lagging auxiliary switches of the converter can attain soft-switching over the entire load range. The conduction and switching losses are greatly reduced compared with those of ordinary converters under the action of the cut-off diodes and auxiliary windings coupled to the main transformer in the auxiliary circuits. The conversion efficiency of the proposed converter is significantly improved, especially under light-load conditions. First, the working principle of the proposed converter is analyzed in detail. Second, the relationship between the different operating modes and the load power is given and the design principle of the auxiliary circuit is presented. Finally, the Saber simulation and experimental results verify the feasibility and validity of the converter and a 50 kW prototype is implemented.

Common-Mode Voltage Elimination with an Auxiliary Half-Bridge Circuit for Five-Level Active NPC Inverters

  • Le, Quoc Anh;Park, Do-Hyeon;Lee, Dong-Choon
    • Journal of Power Electronics
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    • v.17 no.4
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    • pp.923-932
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    • 2017
  • This paper proposes a novel scheme which can compensate the common-mode voltage (CMV) for five-level active neutralpoint clamped (5L-ANPC) inverters, which is based on modifying the space vector pulse width modulation (SVPWM) and adding an auxiliary leg to the inverter. For the modified SVPWM, only the 55 voltage vectors producing low CMV values among the 125 possible voltage vectors are utilized, which varies over the three voltage levels of $-V_{dc}/12$, 0 V, and $V_{dc}/12$. In addition, the compensating voltage, which is injected into the 5L-ANPC inverter system to cancel the remaining CVM through a common-mode transformer (CMT) is generated by the additional NPC leg. By the proposed method, the CMV of the inverter is fully eliminated, while the utilization of the DC-link voltage is not decreased at all. Furthermore, all of the DC-link and flying capacitor voltages of the inverter are well controlled. Simulation and experimental results have verified the validity of the proposed scheme.

Design of a Novel Integrated L-C-T for PSFB ZVS Converters

  • Tian, Jiashen;Gao, Junxia;Zhang, Yiming
    • Journal of Power Electronics
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    • v.17 no.4
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    • pp.905-913
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    • 2017
  • To enhance the zero-voltage switching (ZVS) range and power density of the phase-shift full-bridge (PSFB) ZVS converters used in geophysical exploration, an additional resonant inductor is used as a leakage inductance and a blocking capacitor which is equivalent to interlayer capacitance is integrated into a novel integrated inductor-capacitor-transformer (L-C-T). The leakage inductance and equivalent interlayer capacitance of the novel integrated L-C-T are difficult to determine by conventional methods. To address this issue, this paper presents accurate and efficient methods to compute the leakage inductance and equivalent interlayer capacitance. Moreover, the accuracy of this methodology, which is based on electromagnetic energy and Lebedev's method, is verified by an experimental analysis and a finite element analysis (FEA). Taking the problems of the novel integrated L-C-T into consideration, the losses of the integrated L-C-T are analyzed and the temperature rise of the integrated L-C-T is determined by FEA. Finally, a PSFB ZVS converter prototype with the novel integrated L-C-T is designed and tested.

Parameter and Brightness Characteristic Analysis of Antena for Efficiency Improvement on Electrodeless Fluorescent Lamp (무전극 램프의 효율향상을 위한 안테나의 파라미타 특성 및 휘도특성)

  • Yang, Jong-Kyung;Choi, Gi-Seung;Pack, Gwang-Hyeon;Choi, Yong-Sung;Lee, Jong-Chan;Park, Dae-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.531-534
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    • 2004
  • In Recent, it became necessary to develope the technology about electrodeless fluorescent lamp according to demand of the electodeless fluorescent lamp system that used higher efficiency and advantage of long-lifetime. Especially, in the electordeless fluorescent lamp which used H-mode, efficiency of lamp is decided from matching parameter of antena and inverter. So it is of the utmost importance to design antena and inverter Therefore, this paper used a transformer principle for efficiency rising of electrodeless fluorescent lamp and interpreted an equivalent circuit, used an impedance analyzer in order to confirm a performance enhancement of lamp along design of antenna, and confirmed parameter characteristic of R, L, C, Z, Q-factor along a change of magnetic flux density. Also, this paper confirmed a luminance characteristic of electordeless lamp along parameter change with measuring optical characteristic along a change of magnetic flux density

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