• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1805-1811
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• 2017

Recently, DC systems are considered as efficient electric power systems for renewable energy based clean power generators. This discloses several critical issues that are required to be considered before the installation of the DC systems. First of all, voltage/current switching stress, which is aggravated by large fault current, might damage DC circuit breakers. This problem can be simply solved by applying a superconducting fault current limiter (SFCL) as proposed in this study. It allows a simple use of insulated-gate bipolar transistors (IGBTs) as a DC circuit breaker. To evaluate the proposed resistive type SFCL application to the DC circuit breaker, a DC distribution system is composed of the practical line impedances from the real distribution system in Do-gok area, Korea. Also, to reflect the distributed generation (DG) effects, several DC-to-DC converters are applied. The locations and sizes of the DGs are optimally selected according to the results of previous studies on DG optimization. The performance of the resistive type SFCL applied DC circuit breaker is verified by a time-domain simulation based case study using the power systems computer aided design/electromagnetic transients including DC (PSCAD/ EMTDC(R)).

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.881-885
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• 2018

In order to develop a gas circuit breaker (GCB), the breaking performance of the short line fault (SLF) should be prioritized over that of the breaker terminal fault (BTF). In brief, it is necessary to evaluate the thermal characteristics of the insulating gas that is filled in a GCB. In the process of developing a GCB, many companies use the simplified synthetic testing facility (SSTF).In order to evaluate the SLF breaking performance of a GCB with a long minimum arcing time, a modifications to the conventional SSTF was proposed. In this study, we developed the SSTF with a modified transient recovery voltage circuit. The performance of the newly developed SSTF was verified by an $L_{90}$ breaking performance test on a rating combination of 170 kV, 50 kA, and 60 Hz.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.340-343
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• 2001

In an electrical network, electrical power are transmitted by a various of protection, isolation and control electric circuit devices. This thesis deals with the protection function between circuit-breakers. The protective coordination concerns the behaviour of two devices placed in series in an electrical network, with a short-circuit downstream circuit-breaker. It has two basic principles: First, discrimination which is an increasing requirement of low voltage electrical distribution systems. Second, which is less well known: cascading, which consists of installing a device, whose breaking capacity is less than the three-phase short-circuit current at its terminals and helped by main circuit-breaker. The important advantage of cascading is to be able to install at a branch circuit-breaker of a lesser performance without endangering the safety of the installation for more economical usage. To determine and guarantee co-ordination between two circuit breakers, it is necessary to carry out a theoretical approach, first, and then confirm the results by means of standard tests. This is illustrated in appendix A of IEC 947-2.

• Journal of the Korean Society of Safety
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• v.17 no.1
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• pp.45-53
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• 2002

The purpose of this study was to investigate effect of electrical noise on malfunction of the earth leakage circuit breaker. A three-way experiment for studying its malfunction was conducted, in which electrical products such as radio, alternating current are welder and cellular phone, distance from the earth leakage breaker to electrical products, and whether or not the earth leakage breaker is contained is contained in the steel box were employed as experimental variables. Eleven earth leakage breakers frequently used in real situations were tested in each experimental treatment. The electrical products were used for generating electrical noise that is known to be able to cause malfunction of the earth leakage breaker. The results showed that except a case for one of the 11 earth leakage breakers when the radio made by M company was located 30 cm ahead of the breaker, malfunction did not occur in any other experimental treatment. Consequently, it is suggested that the breaker should be normally used for preventing electricity-related accidents without fear of its malfunction in industrial sites.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.7 s.262
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• pp.777-783
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• 2007

Since the performance of the circuit breaker mainly depends on the spring operating mechanism, the analysis of the spring operating mechanism is required. The spring, especially closing spring, stores the deformation energy due to the compression and then accelerates the big loads rapidly in the circuit breaker. To accurately carry out the kinematic and dynamic analysis of the circuit breaker, the precise modeling of the spring behavior is necessary. In this paper, the static stiffness of the spring is captured by using the tester. A simple mechanism similar to the spring operating mechanism was designed to generate the release motion of the spring. A high speed camera was used to capture the behavior of the spring. Three types of spring models such as a linear spring model, modal spring model, and nodal spring model are suggested and compared with the experimental results.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.523-528
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• 2001

There are many difficult problems in analyzing the flow characteristics in a high voltage circuit breaker such as shock wave and complex geometries, which may be either static or in relative motion. Although a variety of mesh generation techniques are now available, the generation of meshes around complicated, multicomponent geometries like a gas circuit breaker is still a tedious and difficult task for the computational fluid dynamics. This paper presents the computational method for analyzing the compressible flow fields in a high voltage gas circuit breaker using the Cartesian cut-cell method based on the CFD-CAD integration, which can achieve the accurate representation of the geometry designed by a CAD tools. The technique is frequently satisfied, and it will be almost universally so in the future, as the CFD-CAD traffic increases.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.9
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• pp.1566-1570
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• 2007

[ $SF_6$ ] gas circuit breakers are widely used for short circuit current interruption in EHV(Extra High Voltage) or UHV(Ultra High Voltage) power systems. To develop $SF_6$ gas circuit breakers, the arc resistance value is necessary to compare experimental results to numerical ones. The arc resistance value can be obtained from a breaking test with a $SF_6$ gas circuit breaker. The direct testing or synthetic testing facility is widely used to verify the breaking ability for $SF_6$ gas circuit breakers. We employed the simplified synthetic testing facility to test a $SF_6$ gas circuit breaker prototype. The arc resistance characteristic was measured and calculated under the various experimental conditions. This arc resistance value can be used for verifying the numerical results from arc simulation in a circuit breakers.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.222-225
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• 2003

In this paper the performance of the high speed circuit breaker with fault current detector is described. The operating mechanism of circuit breaker in use is a magnetic actuator and a fault current detector is based on the DSP and A/D converter. The results show that 3-cycle is enough to interrupt the fault current and the more speed up performance is expected with on-going project.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.290-291
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• 2010

도통손실이 작고 경제적인 SCR을 이용하여 마이크로그리드에 적용이 가능한 25 [kVA]급 SSCB(Solid-State Circuit Breaker)를 설계하였다. 시뮬레이션을 통하여 3상 단락 사고시의 SSCB 동작특성을 살펴보았고 계통의 용량에 따른 커패시터의 설계값을 제시하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.1
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• pp.25-30
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• 2014

The dynamic characteristics of a gas circuit breaker depend on the underlying high-speed operating mechanism with a spring-actuated latch system. Many studies have been carried out to reduce the breaking time of circuit breakers. In this study, the optimum latch contour design is determined for reducing the breaking time of a circuit breaker. A multi-body dynamic model of the latch is established for analyzing the dynamic behaviors of the circuit breaker by using the MSC/ADAMS program. Simulation results are matched against experimental data. VisualDoc is employed for determining the optimal latch contour. From the optimum design, the breaking time of a gas circuit breaker is improved by about 8.6%.