• Title/Summary/Keyword: MOV

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Analysis on the Effects of TRV and MOV in Real System with TCSC (TCSC가 적용된 실계통 시스템에서의 TRV와 MOV의 영향에 대한 분석)

  • Lee, Seok-Ju
    • Journal of Korea Society of Industrial Information Systems
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    • v.24 no.2
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    • pp.41-46
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    • 2019
  • The application of series compensator in a power system affects other devices such as circuit breakers transient recovery voltage (TRV) problem. In this paper, we analyze the TRV effect on a line circuit breaker in the cases with and without thyristor-controlled series capacitor (TCSC) via simulation, and suggest an effective method to overcome the increase of TRV due to the TCSC installation. It also discusses the impact of proposed protection on metal oxide varistor (MOV). A 345 kV transmission line in Korea was selected as a study case. Grid system was modelled using PSCAD (Power Systems Computer Aided Design) / EMTDC(Electro Magnetic Transient Direct Current). The TRV was analyzed by implementing a short circuit fault along the transmission line and at the breaker terminal. The proposed protection scheme, the TRV satisfies the standard. However, the MOV energy capacity increased as the delay time increased. This result can solve the TRV problem caused by the expected transmission line fault in a practical power system.

Impulse Characteristics of MOV Elements for Railroad Vehicle Arrester (전철 탑재 피뢰기용 MOV 소자 임펄스 특성)

  • Han, S.W.;Cho, H.G.;Lee, H.G.
    • Proceedings of the KIEE Conference
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    • 1999.07d
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    • pp.1529-1531
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    • 1999
  • The main functions of AC railroad vehicles arresters is to protect the main transformer from lightening impulse or switching impulse surge, then the MOV(metal oxide varistor) elements rated of 10kA is applied. The residual voltage and surge energy absorption are important parameters in designing arrester, these must be carefully decided with considering protecting level of impulse environment of system. The purpose of this study is to discuss the residual voltages and the energy absorption capability by impulse currents on MOV elements for railroad vehicles, and to introduce design factors which act as optimal protecting condition against impulse currents.

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The Development of Surge Protection Circuit Applying SCR for Improving Reliability (신뢰도 향상을 위해 SCR을 응용한 서지 보호회로 개발)

  • NamKoong, Up;Chu, Kwang-Uk
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.26 no.8
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    • pp.96-101
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    • 2012
  • A surge protection device of the metal oxide varistor(MOV) has been commonly used for preventing electrical damage in many electronic equipments. The MOV has a property that leakage current is increased and might be permanently damaged when it is exposed continuously to the electrical stresses such as lightening surges. In this paper, we propose a novel surge protection circuit adopting a silicon controlled rectifier(SCR) in the traditional protection circuits using the MOV device simultaneously. When lightning surges are injected to the proposed circuit, the MOV lets the surge pulses bypassing through the ground at first up to the level that SCR begins to operate. Above the threshold level of turning on the SCR, the SCR operates bypasses large surge currents to the ground. Proposed circuit was verified with a leakage current experiment and PSpice circuit simulations under the repeated surge injection environment.

A Study on the Utilization of Metal Oxide Varistor for Low-Voltage AC Circuits (저압 AC회로의 MOV 적용방안 연구)

  • Choi, Hyo-Yul;Lee, Won-Bin;Kang, Young-Suk;Lee, Jae-Bok
    • Proceedings of the KIEE Conference
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    • 1996.07c
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    • pp.1822-1824
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    • 1996
  • Damage and upset of control and communication equipment due to transient overvoltages which occur due primarily to internal switching surge and external lightning surge are an important problems in electromagnetic compatibility(EMC). In this paper, we analyzed operation characteristic of metal oxide varistor widely used low voltage AC line using the electromagnetic transients program(EMTP) and compare it with experimental results and also, we modeled combination generator producing $1.2/50{\mu}s$ open circuit voltage and $8/20{\mu}s$ short circuit current as a source which is critical in calculating operation characteristic. Simulation results showed that most of Transient energy consumes at MOV located in service entrance side than load side, and it showed similar to experimental results. Therefore, entrance side MOV should be selected more energy capacity than that of load side MOV.

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Failure Prediction of Metal Oxide Varistor Using Nonlinear Surge Look-up Table Based on Experimental Data

  • Kim, Young Sun
    • Transactions on Electrical and Electronic Materials
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    • v.16 no.6
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    • pp.317-322
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    • 2015
  • The metal oxide varistor (MOV) is a major component of the surge protection devices (SPDs) currently in use. The device is judged to be faulty when fatigue caused by the continuous inflow of lightning accumulates and reaches the damage limit. In many cases, induced lightning resulting from lightning strikes flows in to the device several times per second in succession. Therefore, the frequency or the rate at which the SPD is actually exposed to stress, called a surge, is outside the range of human perception. For this reason, the protective device should be replaced if it actually approaches the end of its life even though it is not faulty at present, currently no basis exists for making the judgment of remaining lifetime. Up to now, the life of an MOV has been predicted solely based on the number of inflow surges, irrespective of the magnitude of the surge current or the amount of energy that has flowed through the device. In this study, nonlinear data that shows the damage to an MOV depending on the count of surge and the amount of input current were collected through a high-voltage test. Then, a failure prediction algorithm was proposed by preparing a look-up table using the results of the test. The proposed method was experimentally verified using an impulse surge generator

Analysis of Thrust/Torque Signature of MOV (원자력 발전소 모터구동밸브의 쓰러스트/토크 신호 분석)

  • Ryu, Ho-Geun;Park, Seong-Keun;Kim, Dae-Woong
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.613-618
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    • 2001
  • For the evaluation of operability of MOV(Motor Operated Valve), the precision prediction of thrust/torque acting on the valve is important. In this paper, the analytical prediction method of thrust/torque was proposed. The design basis stem thrust calculation typically considers the followings: Packing thrust, Stem rejection load, design basis differential pressure load. In general, test results show that temperature, pressure, fluid type, and differential pressure, independently and combination, all have an effect on the friction factor. The prediction results of thrust/torque are well agrement with dynamic test results.

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Development of a Diagnostic System for Motor-Operated Valves (모터구동밸브 진단장비 개발)

  • Kang, Seong-Ki;Choi, Hyun-Woo;Park, Sung-Keun;Kang, Shin-Chul;Chai, Jang-Bom
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.420-424
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    • 2008
  • The new MOV(motor-operated valve) diagnostic system MOVIDS(MOV intelligent diagnostic system) was developed. Its remote diagnostic methods with high accuracy have improved the applicability. This enables the diagnostic tests and the evaluations of many MOVs not only at the valves but also in remote places like MCCs(motor control centers). The remote diagnostic ability of the new system reduces the cost and the man power for diagnosing MOVs and eliminates the danger of the toxic or radioactive environments to which workers might be exposed.

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Non-Invasive Diagnostic Singature Extraction for Motor-Operated Valves (모터 구동 밸브의 비침투 진단 신호 추출에 관한 연구)

  • ;Richard H. Lyon
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1994.10a
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    • pp.360-364
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    • 1994
  • This paper is concerned with extracting the diagnostic signature for motor-operated valves (MOV's) noninvasively. A torque estimator is developed and tested to obtain electical torque of the induction motors which are attached to the MOV's. Inverse filter is used to recover the gear meshing forces from the measured actuator housing vibration, which contain the gear rotation information. Frequency demodulation techniques are performed and an adaptive linear bandpass filter is implemented to improve signal-to-noise ratio. Finally, stand-alone valve experiments are carried out to validate the signature extraction scheme.

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