• 조명전기설비학회논문지
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• 제27권6호
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• pp.75-81
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• 2013

In this paper, protection coordination between residual current devices and surge protective devices in low-voltage consumer's distribution systems are presented. In the case that a surge protrctive device(SPD) is located on the load side of an residual current device(RCD), when the surge is injected from the source side of the RCD, most of injected surge currents are split into the RCD and the protection coordination between the SPD and RCD is improper, three of 6 specimens experience unintended operation due to test impulse currents. Also when the surges is injected from the load side, a lot of the surge currents is split into the SPD, but a half of test specimens causes nuisance trip. Coordination between SPD and RCD is not valid. When installing SPD, it is important to select SPD after due consideration of the protection voltage level of metal oxide varistor embedded in RCD. It is expected that the results obtained from this work could be useful to improve the protection effects of SPD in low-voltage distribution systems.

• 전기학회논문지
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• 제62권2호
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• pp.190-195
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• 2013

Vacuum circuit breaker(VCB) has been widely used for interruption of load current and fault current for high voltage motor in the industrial field. Its arc extinguishing capability is excellent compared to other breakers. But it has the potential to cause multi reignition surge by high extinguishing capability. Surge voltage is generated by the opening and closing of VCB. Multi reignition surge of VCB is steep-fronted waveform. It may have a detrimental effect on the motor winding insulation. So, most of users install a protection device to limit steep-front waveform at the motor terminal or breaker side. So, most of users install a protection device at the motor terminal or breaker side. This protective device is surge absorber(SA) such as ZnO and RC type. In this study, we analyzed whether there is any effect when two type SA is applied to the VCB multi reignition surge. We confirmed that ZnO SA is slightly more effective than RC SA for reduction of multi reignition surge.

• 한국정보통신학회논문지
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• 제9권2호
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• pp.289-294
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• 2005

본 논문은 변전소내 정보기기에 나타나는 서지전압 전류의 측정 결과에 대해 기술하였다. 서지전압 전류 관측을 위한 전력분석기는 전력용 변압기와 개폐기 주변의 신호선에 설치하였으며, 전력분석기의 시간분해능은 4 MS/s이다. 측정된 서지전압.전류의 크기는 각각 500~1,300v와 500~3,100k 이었으며, 측정기간 동안 평균 5~10회/일 이상의 서지가 기록되었다. 따라서 고전압 전력설비 주변에 설치되는 정보기기는 설치환경에 나타나는 서지의 크기를 고려하여 설계되어야 할 것이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1712-1714
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• 1997

This paper deals with the surge counter drived by lightning and switching currents. In order to install the effective surge protective devices, it is important to find the parameters of incident surges. In this paper, for the purpose of protecting the electronic circuits and counting the occuring frequency, the current driving type surge counter is designed and fabricated. The surge counter consists of surge protective divices, current detector, metal oxide varistor(MOV), rectifier, capacitor, and electromagnetic counter. This surge counter is able to count the occuring frequency of surges and to clamp lightning surge current. To evaluate the performance of the surge counter, impulse voltage and current were applied at the surge counter by the surge generator. As a result, applied surges were exactly counted and clamped.

• 조명전기설비학회논문지
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• 제27권3호
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• pp.79-86
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• 2013

In order to analyze the electrical performance of ZnO surge arresters stressed by the combined DC and AC voltages that are generated in DC/AC converter systems, the leakage current properties of ZnO surge arrester blocks deteriorated by impulse currents were investigated. The test specimens were deteriorated by the 8/$20{\mu}s$ impulse current of 2.5kA and the leakage currents flowing into the deteriorated zinc oxide(ZnO) arrester blocks subjected to the combined DC and power frequency AC voltages are measured. As a result, the leakage currents flowing through deteriorated ZnO surge arrester blocks were higher than those flowing through the fine ZnO surge arrester blocks and the larger the injection number of 8/$20{\mu}s$ impulse current of 2.5kA is, the greater the leakage current is. The leakage current-voltage curves(I-V curves) of the fine and deteriorated ZnO surge arrester blocks stressed by the combined DC and AC voltages show significant difference in the low conduction region. Also the cross-over phenomenon is observed at the voltage close to the knee of conduction on plots of I-V curves.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.190-193
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• 2001

ZnO varistors have been widely used to protect power system and electronic system against overvoltages based on their excellent nonlinearity. In order to increase their protection capability, the fracture and protection technologies of arresters have to study according to their applications, namely ImA DC voltage, leakage currents, impulse residual voltages, withstanding capability to impulse surge, and energy absorption capability. ZnO varistors which have nonlinear current-voltage characteristic name a number of failure mechanism when ZnO elements absorb surge energies. Failure mode by thermal stress and Pin hole are among the most common failure mechanism at the high current surge current. In this study, the fracture mechaism of power arresters are introduced and protection technologies are researched. In particular the effect of thermal stress by surge currents to ZnO elements and methods against arc surge energy through withstand structure design of arrester are discussed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1892-1896
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• 2008

Inverter-fed induction motors (IFM) are prevalent in traction vehicles. However, the winding insulation of IFM is substantially more stressed than of line-powered motors by surge voltages. Consequently, the winding insulation of IFM should be estimated by surge voltages. Also, the weakness of coil insulation can be detected by the surge voltage test. This paper described the insulation evaluation of induction motors by application of surge voltages. A surge voltage generator with the maximum voltage of 5 kV and the selectable rise-time in ranges of $50\;ns\;{\sim}\;500\;ns$ was fabricated. In the experiment, we applied surge voltages into induction motors with the magnitude and the risetime according to IEEE 522. By the analysis of applied surge voltage and current waveforms, we could find difference between normal and defection windings.

• 조명전기설비학회논문지
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• 제29권3호
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• pp.81-87
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• 2015

In order to effectively protect electrical and electronic circuits which are extremely susceptible to lightning surges, multi-stage surge protection circuits are required. This paper presents the operational characteristics of the two-stage hybrid surge protection circuit in extra-low voltage DC power lines. The hybrid surge protective device consists of the gas discharge tube, transient voltage suppressor, and series inductor. The response characteristics of the proposed hybrid surge protective device to combination waves were investigated. As a result, the proposed two-stage surge protective device to combination wave provides the tight clamping level of less than 50V. The firing of the gas discharge tube to lightning surges depends on the de-coupling inductance and the rate-of-change of the current flowing through the transient voltage suppressor. The coordination between the upstream and downstream components of the hybrid surge protective device was satisfactorily achieved. The inductance of a de-coupler in surge protective circuits for low-voltage DC power lines, relative to a resistance, is sufficiently effective. The voltage drop and power loss due to the proposed surge protective device are ignored during normal operation of the systems.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.128-131
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• 2000

The main objective of this paper is to design and test a new type of polymer ZnO surge arrester for DC power system of railroad vehicles. The rated voltage is 1500V direct current. The main research works are focused on structure design by finite element method, rating voltage, temporary over voltage and studies of characteristics of polymeric surge arrester.

• 한국정보통신학회논문지
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• 제9권3호
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• pp.570-575
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• 2005

저전압 전력계통에 사용되는 누전차단기의 서지에 대한 오동작은 심각한 문제이다. 본 논문에서는 누전차단기의 서지에 대한 영향을 분석하기 위하여 IEC 61009-1와 KS C 4613 규격에 따라 누전차단기를 시험하였다. 서지전압 시험은 국내외 규격에 모두 적용되고 있으며, 서지전류 시험에 대해서는 국제규격 IEC 61009-1에만 규정되어 있다. 실험결과로부터 누전차단기는 서지전압에 대해서는 강인하지만 서지전류에 대해서는 오동작을 발생시켰다. 실제로 누전차단기가 설치되어 있는 환경에서는 서지전류의 침입이 빈번하므로, 누전차단기는 서지전류에 의한 오동작 시험이 수행되어야 하며, 국내규격에도 누전차단기 시험에 서지전류에 의한 평가를 포함하여야 할 것이다.