• Title, Summary, Keyword: Transformer

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A Study on the Safty Diagnosis and Evaluation of Oil-immersed Transformer using fuzzy Algorithm (퍼지 알고리즘을 이용한 유중 변압기의 안전진단 및 평가에 관한 연구)

  • Kim, Young-Il
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.55 no.4
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    • pp.190-195
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    • 2006
  • In this paper, safety algorithm of transformer is introduced for the sake of MV/LV distribution customers by using fuzzy theory. The current-carrying capacity of transformer is usually determined by the maximum temperature at which the transformer is permitted to operate. Overload of transformer has an effect on transformer utilization rate and maximum temperature rises as well as maximum ambient temperature of insulating materials. Therefore, we proposed the safety algorithm considering the overload of transformer and ambient temperature in this paper. We introduced the correlational equations between each parameters using experimental data of IEEE std C57.91-1995, and deduced the result using fuzzy reasoning. We guessed the safety algorithm making a diagnosis for the safety status of oil-immersed transformer.

Detection of the Ultrasonic Signals due to Partial Discharges in a 154kV Transformer

  • Kweon, Dong-Jin;Chin, Sang-Bum;Kwak, Hee-Ro
    • KIEE International Transactions on Electrophysics and Applications
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    • v.2C no.6
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    • pp.297-303
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    • 2002
  • We have developed an on-line ultrasonic detector to monitor partial discharge in an operating transformer. The ultrasonic sensor has 150[KHz] resonance frequency and contains a pre-amplifier with 60[㏈] gain. The on-line ultrasonic detector has 50~300[KHz] frequency band-pass filter to remove electrical and mechanical noises from the transformer. This detector has an ultrasonic signal discrimination algorithm which discriminates ultrasonic signals due to partial discharge in a transformer. A moving average method of ultrasonic signal number was employed to effectively monitor the increasing trend of the partial discharge. This paper describes an experience of partial discharge detection in a 154[㎸] operating transformer using an ultrasonic detector. With regards to gas analysis in oil, C2H2 gas was produced with a warning level in this transformer We detected ultrasonic signals on the transformer steel wall, and estimated the position of partial discharge. With further inspection, we found carbonized marks due to partial discharge on the supporting bolt which fastens the windings.

Analysis of Vibration-Frequency Spectrum of Distribution Transformer for Noise Reduction (배전용변압기의 소응저감을 위한 진동주파수의 스펙트럼분석)

  • Lee, Do-Hoon;Kim, Jae-Chul;Song, Seung-Youp;Lee, Hyun-Gu;Kim, Kwang-Whoa
    • Proceedings of the KIEE Conference
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    • pp.346-348
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    • 2002
  • This paper analyze spectrum of vibration-frequencies to reduce noise level of distribution transformer. Using loading back method on same condition of a real load to grasp the effect of core and winding which are caused by the transformer vibration. we were measured the vibration-frequency by varing applied voltage and load current of a transformer. The major cause of a transformer vibration is occured by the harmonic effects, and was identified that the vibration is less influenced by the coil. As the result of this paper, comparing the transformer with some isolated material with the general transformer the transformer with some isolated material could reduce spectral amplitude of vibration-frequencies.

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Thickness-Vibration-Mode Piezoelectric Transformer for Power Converter

  • Su-Ho lee;Yoo, Ju-Hyun;Yoon, H.S.
    • Transactions on Electrical and Electronic Materials
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    • v.1 no.3
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    • pp.1-5
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    • 2000
  • This paper presents a new sort of multilayer piezoelectric ceramic transformer for switching regulation power supplies. This piezoelectric transformer operate in the second thickness resonant vibration mode. Accordingly its resonant frequency is higher than 1 NHz, Because output power is low if input and output part of transformer are consisted of single layer, this research suggests a new method, which is consisted of both input and output part of transformer have 2-layered piezoelectric ceramics, The size of transformer is 20 mm in width and length, and 1.4 mm in thickness, respectively, To design a high efficient switching circuit of the transformer, internal circuit parameters were measured and then weve calculated a parameter of inductor nd capacitor to design a driving circuit, Weve used a MISFET and its driver circuit modified a calp oscillator circuit as the primary switching circuit.

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Evaluation of Damage from Reclosing Scheme for Power Transfromer (재폐로방식이 전력용 변압기에 미치는 영향 평가)

  • O, Jeong-Hwan;Yun, Sang-Yun;Im, Seong-Jeong;Kim, Jae-Cheol
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.3
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    • pp.177-183
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    • 1999
  • This paper presents how to evaluate the transformer damage caused by reclosing scheme at the distribution substation. We describe a quantitative relationship between the reclosing scheme and the number of fault current flowing through transformer wsing the probability of a reclosing success/failure. The transformer damage from reclosing scheme is presented using a weight function and a damage function. A weight function is associated with the number of reclosing attempts and the reclosing deadtime to consider cumulative stress caused by reclosing scheme. A damage function is associated with a transformer impact ratio and a transformer functional life. In the case study, the transformer damage is simulated for the probability of a reclosing success. And the evaluation of transformer damage using KEPCO's operation data is performed.

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A Study on Characteristics of Step-down Piezoelectric Transformer Using Contour Extended Vibration Mode (경방향 확장 진동모드를 이용한 강압용 압전변압기의 특성에 관한 연구)

  • Lee, Won-Jae;Min, Bok-Ki;Song, Jae-Sung;Chong, Hyon-Ho;Park, Tae-Gon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.638-641
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    • 2002
  • This paper presents design and construct of flat type step-down piezoelectric transformer for the application to AC-adapters. This piezoelectric transformer operated in resonance vibration mode. In this paper, Finite element method(FEM) was used for analysis piezoelectric transformers. Vibration mode and electric field of piezoelectric transformer at resonance frequency were simulated. Using this simulation, we manufactured flat type piezoelecric transformer and measured its output characteristics. As results, output power was linearly increased by increasing input power at resonance frequency. And it was found that the transformer exhibited an output power of 11.4[W] at 60[V] input voltage. From these results, we expect that this piezoelecric transformer can be applied to AC adapters.

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A Study on Standards of Transformer Noise Level for Outdoor Substation (옥외 변전소 변압기의 소음레벨 기준에 대한 연구)

  • Koo, Kyo-Sun;Kweon, Dong-Jin;Kwak, Ju-Sik
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.12
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    • pp.2213-2219
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    • 2008
  • Customer complaints on noise from the power transformer have been increased because of their concerns on environment. In order to solve fundamental noise problem of the transformer, KEPCO and domestic transformer manufacturers are developing 55 dBA class low noise transformers. To check accordance of the noise abatement law, we study relation between transformer noise level and substation border noise level. We present 'noise level of the substation border' under operating conditions and transformer noise level change. We also present an appropriate noise level of the transformer that satisfy the noise abatement law for outdoor substations.

3kW multi-string photovoltaic inverter design and simulation (3kW 멀티스트링 태양광 인버터 설계 및 시뮬레이션)

  • Lee, Jong-In;Yu, Beyng-Gyu;Yu, Gwen-Jong;Kim, Heung-Geun
    • 한국태양에너지학회:학술대회논문집
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    • pp.371-376
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    • 2009
  • The Power Conditioning System is Power Transfer System which make array DC current to the Grid sinusoidal current. These are Low Frequency Transformer Inverter Type, High Frequency Transformer Inverter Type and Transformer-less Type. Low Frequency Transformer Type has a Excellent Isolation property, but doesn't have competitiveness in Size and Cost. Also High Frequency Transformer Type has a good Isolation property but there are many steps in Power transfer Switching. Nowadays, Transformer-less Type inverter change a transformer to DC/DC Converter which is small and cost effective. In this paper shown the DC/DC Converter Transformer-less Type multi-string inverter design and simulation. The Control Algorithm will be introduced and Simulation was accomplished.

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Ageing Diagnostics in Oil Transformer for Large Capacity due to Test methods (시험방법에 의한 대용량 유입변압기의 열화진단)

  • Sim, Yoon-Tae;Kim, Wang-Gon;Hong, Jin-Woong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.96-99
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    • 2003
  • In this paper, ageing diagnostics in the large capacity oil transformer are investigated. Following items are investigated for the ageing diagnostic in transformer oils (leakage current of sensor, power consumption and temperature of transformer oil). All temperature data are gathered from daily report in the substation. The power consumption of transformer are gathered output report of APIS(Airport Power Information System). Especially, data of sensor leakage current are accumulated from the online diagnostic system for transformer oil. The temperature of transformer oils major change factor was ambient temperature and capacity of power load. The leakage current are change by oil temperature. The leakage current ware not more than 2 [nA] in summer,

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Analysis of Transient Characteristics of SFCL using the Three-Phase Transformer and Power Switch (삼상 변압기와 전력용 스위치를 이용한 초전도 한류기의 과도특성 해석)

  • Jung, Byung-Ik;Choi, Hyo-Sang;Park, Jung-Il;Cho, Geum-Bae
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.11
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    • pp.1743-1747
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    • 2012
  • The research of superconducting fault current limiter (SFCL) for reduction of the fault current is actively underway in the worldwide. In this paper, we analyzed the characteristics of a SFCL using the transformer and superconducting elements combined mutually in accordance with the fault types. The structure of this SFCL was composed of the secondary and third windings of a transformer connected to the load and the superconducting element, respectively. The provided electric power flew into the load connected to the secondary winding of the transformer in normal state. On the other hand, when the fault occurred in power system, the fault current was limited by closing the line of third winding of the transformer. At this time, the effect of the fault was minimized by opening the fault line in secondary winding of a transformer in power system. The sensing of the fault state was performed by the current transformer(CT) and then turn-on and turn-off switching behavior of the secondary line in the transformer was performed by the silicon-controlled rectifier(SCR). As a result, the proposed SFCL limited the fault current within one-cycle efficiently. Also, the degradation of the superconducting element in the normal state was avoided.