• Title/Summary/Keyword: E-J power

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The Improvement of NGR for Power Transformer Open Circuit Protection (전력용변압기 단선 보호용 NGR 성능 개선)

  • Kang, Y.W.;Shim, E.B.;Kwak, J.S.
    • Proceedings of the KIEE Conference
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    • 2004.11d
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    • pp.83-88
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    • 2004

  • As the electric system is getting larger to meet the increasing demand for electric power, the rating of power apparatus is becoming inevitably higher in its working voltage and larger in its capacity. According to KEPCO reports, power transformers in the KEPCO system have undergone troubles such as winding short insulation breakdowns every year since 1981. the cause of this troubles were high one line grounding fault currents in KEPCO systems that had direct grounding systems. KEPCO has installed the NGR(neutral grounding reactor) to lower this fault current and reduced winding short insulation breakdowns in power transformers. But when a circuit breaker opened a no load bus, some trips of circuit breakers for protecting transformer have occurred by mal-operation of 59GT(overvoltage ground relay) that detect disconnection of NGR. Therefore, in this paper, we analyzed the cause and examined the effect of time delav circuit to prevent wrong operation of 59GT.

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Development of Variable Torque Inverter from $37{\sim}280[kW]$ to 280[kW] ($37{\sim}280[kW]$ VT 인버터 개발)

  • Kwon, B.H.;Kim, J.H.;Na, S.H.;Hong, C.O.;Lee, J.P.;Park, C.H.;Park, E.S.;Kim, K.M.;Yoon, H.M.;Lee, K.J.
    • Proceedings of the KIPE Conference
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    • 2005.07a
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    • pp.51-53
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    • 2005

  • This paper focuses on the power circuit section of newly developed LSIS inverter for the variable torque application and presents the detailed explanation on the power circuits as well as its application-specific functional performance.

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