• 한국초전도ㆍ저온공학회논문지
• /
• 제10권2호
• /
• pp.30-33
• /
• 2008

Several kinds of superconducting fault current limiters (SFCLs), which reduces huge fault current, have been developing by many research groups. The SFCL has no impedance during normal operation, so it dose not give any influence to electric power system. The resistive type SFCL reduces the fault current with the impedance generated in the superconducting part of the SFCL when the fault current exceeds the critical current of SFCL. In this paper, a new type resistive SFCL made of bifilar coil wound with two different high-Tc superconducting (HTS) wires in parallel. Although a bifilar coil has theoretically no inductance, the bifilar coil made in this paper could generate inductance at fault. The specifications of the used two wires were considerably different, thus current distribution between the two HTS wire was different at fault. When the fault current exceeded the critical current of one wire in the bifilar coil, the momentary sharp increase of impedance was detected. Base on the results, a new resistive type SFCL can generate not only resistance but also inductance, which can be used to control a fault current in the future.

• 조명전기설비학회논문지
• /
• 제21권9호
• /
• pp.109-113
• /
• 2007

In this paper, an arc current controller was designed for the interruption of arc fault currents occurred in a low voltage network. Arc in an electrical network represents the characteristics of low current, high impedance, and high frequency. Conventional controllers do not have arc current interrupt functions. Thus, an arc current controller was designed for the interruption of arc fault currents.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2007년도 춘계학술대회 논문집
• /
• pp.463-467
• /
• 2007

It is necessary to study the prevention and the management of electrical facilities because the electrical fault took place at the dust occurrence area due to environmental pollution. In particular, the dust accumulates easily on insulation material which is exposed an external long time. The leakage current brings out electrical fault after all. Also, it is need to variation of material and shape to repress a leakage current on electrical material. In this paper, we measured a leakage current on electrical material of facilities by dust, and in experiments the prevention to electrical fault was studied.

• Journal of Power Electronics
• /
• 제13권3호
• /
• pp.349-361
• /
• 2013

As a result of the advantages such as high efficiency, continuous current and high stability margin, push-pull converter with continuous current (PPCWCC) is competitive for battery discharge regulator (BDR) which plays an important role in power conditioning unit (PCU). Leakage inductance yields current spike in low-ripple current of PPCWCCs. The operating modes are added due to leakage inductance. Therefore the steady state performance is affected, which is embodied in the spike of low-ripple current. PPCWCCs which are suitable for BDR can be separated into three types by current spike characteristics. Three representative topologies IIs1, IIcb2 and Is3 are analyzed in order to investigate the factors on the magnitude and duration of spike. Equivalent current sampling method (ECSM) which eliminates the sampling time delay and achieves excellent dynamic performance is adopted to prevent the spike disturbance on current sampling. However, ECSM reduces the sampling accuracy and telemetry accuracy due to neglecting the spike. In this paper, ECSM used in PPCWCCs is summarized. The current sampling error is analyzed in quality and quantity, which provides the foundation for offsetting and enhancing the telemetry accuracy. Finally, current sampling error rate of three topologies is compared by experiment results, which verify the theoretical analysis.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
• /
• pp.1540-1541
• /
• 2006

For limitation and interruption of short circuit currents from low voltage to extra high voltage applications, the electrical equipment including fuses and circuit breakers, are widely used today. But in order to anticipate increasing needs for effective and competitive device for limiting the growing fault current in electrical power systems, fault current limitation technologies and fault current limitation devices are widely introduced and investigated in these days. Fault current limiters are emerging electric equipment which is under development using various methods including superconducting fault current limiter, solid state fault current limiter, arc driving fault current limiters. And these various methods have some advantages and disadvantages to take into considerations In order to commercialize fault current limiters in the electrical networks, a lot of discussions should be given on the point that fault current limiting methods, need for fault current limiters, coordination with existing protective system, and field experience before commercialization. In this paper, recent trends of fault current limiting technologies will be reviewed and the key issues of superconducting fault current limiters will be dealt with. And finally, future applications of superconducting fault current limiters would be discussed.

• 전기학회논문지
• /
• 제57권1호
• /
• pp.46-51
• /
• 2008

Extra-high voltage(EHV) disconnecting switch(DS) consists of the electrical contacts and mechanical parts which actuate the contacts. When the short-circuit condition occurs, a large amount of current flows through the electrical contact in disconnecting switches and this causes considerable temperature rise due to Joule heating. If the temperature rise is higher than the melting point of contact material, the DS contact becomes melting and cannot be usable anymore. For this reason, the analysis for capability of carrying short-circuit current in DS contacts must be performed at a design stage. Here, we proposed a numerical technique for evaluating the capability of carrying short-circuit current at electrical contacts in EHV DS. In this numerical approach, the mechanical and thermal analyses were simulated to check the capability of carrying short-circuit current. First, the applied pressure at contact parts was analyzed considering the mechanical properties, and then contact resistance was calculated by an empirical equation. Finally, thermal analysis was performed with resistance variation at electrical contacts. To verify these numerical results, the distributions of temperature in DS were experimentally measured and compared with each other. The results from experiments were agreed well with those from the proposed numerical simulations.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
• /
• pp.907-909
• /
• 1998

This paper describes the effect of impulse current on degradation of ZnO blocks. In this study, an impulse current generator which can produce 8/20 [${\mu}s$], 3 [kA] and 4/10 [${\mu}s$], 5 [kA] waveform is designed and fabricated to simulate the lightning impulse current. The residual voltage, reference voltage, and leakage current flowing to the ZnO blocks are observed. The experimental results show that the leakage current increases continuously with the number of applied impulse current, but no significant changes in residual voltage and in operating voltage are observed until the ZnO block is destroyed. Also, it is confirmed that the main factor on degradation of ZnO blocks is rather the total energy applied to ZnO blocks than the peak value of the impulse current.

• International Journal of Control, Automation, and Systems
• /
• 제6권4호
• /
• pp.613-619
• /
• 2008

A method to produce a desired current pattern in a multiple-source EIT system using voltage sources is presented. Application of current patterns to a body is known to be superior to the application of voltage patterns in terms of high spatial frequency noise suppression, resulting in high accuracy in conductivity and permittivity images. Since current sources are difficult and expensive to build, the use of voltage sources to apply the current pattern is desirable. An iterative algorithm presented in this paper generates the necessary voltage pattern that will produce the desired current pattern. The convergence of the algorithm is shown under the condition that the estimation error of the linear mapping matrix from voltage to current is small. Simulation results are presented to illustrate the convergence of the output current.

• 전기학회논문지
• /
• 제60권4호
• /
• pp.885-891
• /
• 2011

In this paper, we studied dc leakage current properties analysis of LED lamps of road and landscape lighting when leakage current appeared in dc power line. Generally, converter of LED lighting is divides to insulated type and non-insulated type according to components. When electric leakage happened in AC power line, earth leakage breaker(ELB) senses leakage current and interrupts electric circuit. In dc power source, We need experimental verification about dc electric leakage for electricity safety. In normal wiring conditions and in the water, in case of using insulated type of converter, dc leakage current did not occur. However, in case of using non-insulated type of converter, dc leakage current occurred and passed through into the ground. We found that there is a hazard of electric shock by dc leakage current. We expect that the results of these studies would be helpful for electrical safety of LED lamps for road and landscape lighting.

• 조명전기설비학회논문지
• /
• 제25권7호
• /
• pp.92-96
• /
• 2011

In this paper, in order to reduce the electrical disaster such as electrical fire at traditional markets, we need to develop the ESMS(electrical safety monitoring system) which is able to monitor the power status of electrical equipments. Therefore, for solving the those problems, we developed the detection censor(ZCT, CT) and equipment of data analysis and transmission. The detection censor and equipment are able to monitor the electrical equipments condition(over current, leakage current, arc, etc.). We constructed Test-Bed for testing reliability of the ESMS and obtained certification. And we tested the over current, leakage current and arc under the normal condition.