• Title/Summary/Keyword: reference voltage test

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Development of ZnO Varistor for Distribution Surge Arrester (18kV, 5kA) (배전급 피뢰기(18kV, 5kA)용 ZnO 바리스터 소자 개발)

  • 박춘현;윤관준;조이곤;정세영;서형권
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.11a
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    • pp.212-216
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    • 2000
  • ZnO varistors for distribution surge arrester (18kV, 5kA) were developed and tested microstructure and electrical characteristics. Microstructure of ZnO varistor was consisted of ZnO grain, spinel phase and Bi-rich phase. Average grain size of ZnO varistor was $\mu\textrm{m}$ Reference voltage and lightning impulse residual voltage of ZnO varistor exhibited a good haracteristics above 5.5kV and below 11.56kV, respectively. Consequently, discharge capacity which is the most important characteristics of ZnO varistor for surge arrester exhibited excellent properties above 70kA at twice high-current impulse test. Moreover, variation rate of reference voltage and lightning impulse residual voltage showed below 5% and 2% after high-current impulse test, respectively. Leakage current and watt loss of ZnO varistor will not increase during accelerated aging test at stress condition, such as 3.213kV/$115^{\circ}C$/1000h.

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Evaluation of Long Duration Current Impulse Withstand Characteristics of ZnO Blocks for High Voltage Surge Arresters (초고압 피뢰기용 ZnO 소자의 장시간 방전내량 특성 평가)

  • Cho, Han-Goo;Yun, Han-Soo;Kim, Seok-Soo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.4
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    • pp.398-403
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    • 2006
  • This paper describes the evaluation of the long duration current impulse withstand characteristics of ZnO blocks for high voltage surge arresters. Four ZnO varistors were manufactured with the general ceramic production method and the long duration current impulse withstand test, electrical uniformity evaluation test and microstructure observation were performed. All varistors exhibited high density, which was in the range of $5.42{\sim}5.46g/cm^3$. In the electrical properties, the reference voltage of samples was in the range of $5.11{\sim}5.25\;kV$ and the residual voltage was in the range of $8.314{\sim}8.523\;kV$. In the long duration current impulse withstand test, sample No.2 and No.3 failed at the 2nd and 4th shot of series impulse currents, respectively, but the rest survived 18 shots during the test. Before and after this test, the variation ratio of the residual voltage of samples survived was below 0.5 %, which was in the acceptance range of 5 %. According to the results of the test, it is thought that if the soldering method is improved, ZnO varistors would be possible to apply to the high voltage arresters like the station class and transmission line arresters in the near future.

Electrical Characteristics and Performance Evaluation with Manufacturing Process of Zinc Oxide Varistors (산화아연소자의 성형공정에 따른 전기적 특성과 성능평가)

  • Cho, Han-Goo;Yoon, Han-Soo;Kim, Suk-Soo;Choi, In-Hyuk
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.11
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    • pp.1061-1066
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    • 2006
  • This paper presents the electrical characteristics with manufacturing process and performance evaluation of high performance zinc oxide varistors. ZnO varistors were fabricated with typical ceramic production methods with different thickness and the structural and electrical characteristics of ZnO varistors were investigated. All varistors exhibited high density, which was in the range of $5.41{\sim}5.49g/cm^3$. In the electrical properties, the reference voltage increased in the range of $4.410{\sim}5.250kV$ with increasing their thickness and the residual voltage exhibited the same trends as the reference voltage. In the long duration current impulse withstand test, E-2 and F-1 samples failed at the two and four shots of impulse current, respectively, but E-1 and F-2 samples survived 18 shots during the test. Before and after this test, the variation ratio of residual voltage of E-1 and F-2 samples were -0.34 % and 0.05 %, respectively, which were in the acceptance range of 5 %. According to the results of tests, it is thought that if the fabrication process such as insulating coating, sintering condition, and soldering method is improved, these ZnO varistors would be possible to apply to the station class arresters in the near future.

Start-up circuit with wide supply swing voltage range and modified power-up characteristic for bandgap reference voltage generator. (넓은 전압 범위와 개선된 파워-업 특성을 가지는 밴드갭 기준전압 발생기의 스타트-업 회로)

  • Sung, Kwang-Young;Kim, Jong-Hee;Kim, Tae-Ho;Vu, Cao Tuan;Lee, Jae-Hyung;Lim, Gyu-Ho;Park, Mu-Hum;Ha, Pan-Bong;Kim, Young-Hee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.8
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    • pp.1544-1551
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    • 2007
  • A start-up circuit of the bandgap reference voltage generator of cascode current mirror type with wide operating voltage range and enhanced power-up characteristics is proposed in the paper. It is confirmed by simulation that the newly proposed start-up circuit does not affect the operation of the bandgap reference voltage generatory even though the supply voltage(VDDA) is higher and has more stable power-up characteristic than the conventional start-up circuit. Test chips are designed and fabricated with $0.18{\mu}m$ tripple well CMOS process and their test has been completed. The mean value of measured the reference voltage(Vref) is 738mV and The three sigma value($3{\sigma}$) is 29.88mV.

Psophometeric Noise Voltage of Telecommunication Lines and Test methods (통신회선의 잡음전압 기준 및 측정법)

  • Hwang, Jong-Sun;Kim, Yeong-Min;Lee, Kyoung-Wook;Kim, Jae-Joon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11b
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    • pp.617-620
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    • 2001
  • The protection of communication lines against harmful effects from electricity lines is very important with the rapid development of communications network. This paper is introduced the reference of noise voltage and the test methods of foreign countries. Further we will also present study measurement equipment for telecommunications noise voltage and circuit noise phenomenon.

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Psophometeric Noise Voltage of Telecommunication Lines and Test methods (통신회선의 잡음전압 기준 및 측정법)

  • 황종선;김영민;이경욱;김재준
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11a
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    • pp.617-620
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    • 2001
  • The protection of communication lines against harmful effects from electricity lines is very important with the rapid development of communications network. This paper is introduced the reference of noise voltage and the test methods of foreign coutnreis. Further we will also present study measurement equipment for telecommunications noise voltage and circuit noise phenomenon.

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A Study on the Improvement of ZnO Varistor for Distribution Class Surge Arrester(18kV, 5kA) (배전급 피뢰기(18kV, 5kA)용 산화아연바리스타의 성능향상에 관한 연구)

  • Yoo, Deok-Son;Yoon, Han-Soo;Kim, Suk-Soo;Choi, Yeon-Gyu;Jang, Sung-Do
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07b
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    • pp.744-746
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    • 2003
  • A ZnO varistor with reference voltage 250V/mm was fabricated through the control of particle size in slurry and the variation of sintering conditions. It was found that to measure the flatness of the V-I characteristic curve in the small-current region and the flatness of the V-I characteristic curve in a large-current region was improved nonlinearity of the fabricated ZnO varistor. According to the IEC 60099-4 was measured the accelerated aging test and high current test of the distribution class surge varistor which is excellent in respect to the property of ZnO varistor.

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Multistage Inverters Control Using Surface Hysteresis Comparators

  • Menshawi, Menshawi K.;Mekhilef, Saad
    • Journal of Power Electronics
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    • v.13 no.1
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    • pp.59-69
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    • 2013
  • An alternative technique to control multilevel inverters with vector approximations has been presented. The innovative control method utilizes specially designed two-dimensional hysteresis comparators to simplify the implementation and improve the resultant waveform. The multistage inverter designed with maximum number of levels is operated in such a way to approximate the reference voltage vector by exploiting the large number of multilevel inverter vectors. A three-stage inverter with the main high voltage stage made of three phase, six-switch and singly-fed inverter is considered for application to the proposed design. The proposed control concept is to maintain a higher voltage stage state as long as it can lead to a target vector. High and medium voltage stages controllers are based on surface hysteresis comparators to hold the switching state or to perform the necessary change to achieve its reference voltage with minimal switching losses. The low voltage stage controller is designed to approximate the target reference voltage to the nearest inverter vector using the nearest integer rounding and adjustment comparators. Model simulation and prototype test results show that the proposed control technique clearly outperforms the previous control methods.

Fabrication and Performance Evaluation of Zinc Oxide Varistors for the Arresters used for Station System (발변전소 피뢰기용 산화아연소자의 제작 및 성능평가)

  • Cho, Han-Goo;Han, Se-Won;Kim, Suk-Soo;Yoon, Han-Soo;Lee, Un-Yong;O, Cheol-Gyu;Yu, Kun-Yang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.636-639
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    • 2004
  • This paper presents the fabrication and performance evaluation of zinc oxide varistors for the arresters used for station system. ZnO varistors were fabricated with typical ceramic production methods and the structural and electrical characteristics were investigated. All varistors exhibited high density, which were in the range of $5.41{\sim}5.49g/cm^3$. In the electrical properties the reference voltage increased in the range of $4.410{\sim}5.250kV$ with increasing their thickness and the residual voltage exhibited the same trends as the reference voltage. In the long duration current impulse withstand test, E-2 and F-1 samples failed in the two and four shots, respectively, but E-1 and F-2 samples survived 18 shots during the test. Before and after this test, the variation ratio of residual voltage of E-1 and F-2 samples were -0.34% and 0.05%, respectively, which were in the acceptance range of 5%. According to the results of tests, it is thought that if the fabrication process such as insulating coating, sintering condition, and soldering method is improved, these ZnO varistors would be possible to apply to the station class arresters in the new future.

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The Determination of Reference Impedance on 1P2W Low Voltage System in Korea (국내 단상2선식 저압 배전계통 기준임피던스 선정에 관한 연구)

  • Kang, Moon-Ho;Song, Yang-Hyao;Lee, Heung-Ho
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.10
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    • pp.35-39
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    • 2007
  • Home appliances, like air-conditionals, washers, refrigerators, etc., can cause voltage fluctuations and light flicker. A standardized flicker test has been established in Europe(IEC 61000-3-3, IEC 61000-3-11). The supply impedance of power supply system varies from plate to place, and for the flicker test in KOREA, the appliance manufacturers do need standardized impedance like the one indicated in IEC 61000-3-3 for 230[V]/50[Hz]. Without it, the same appliance will have different flicker level at different places. For appliance manufacturers, the flicker limit should be related to the reference impedance. However, the European flicker test is designed for 230[V]/50[Hz] power and needs to be modified for a 1P2W(220[V]/60[Hz]) supply system in KOREA. In this paper, the reference impedance for KOREA(220[V]/60[Hz]) systems is proposed. The measured result provided in this paper was served as a proposal for establishing KOREA reference impedance for 220[V]/60[Hz] and has been published in IEC 60725.