• Journal of Power Electronics
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• 제12권1호
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• pp.208-214
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• 2012

This paper presents a novel approach based on the loci of instantaneous symmetrical components called "Wing Shape" which requires the measurement of three input stator currents and voltages to diagnose interturn insulation faults in three phase induction motors operating under different loading conditions. In this methodology, the effect of unbalanced supply conditions, constructional imbalances and measurement errors are also investigated. The sizes of the wings determine the loading on the motor and the travel of the wings while their areas determine the degree of severity of the faults. This approach is also applied to detect open circuit faults or single phasing conditions in induction motors. In order to validate this method, experimental results are presented for a 5 hp squirrel cage induction motor. The proposed technique helps improve the reliability, efficiency, and safety of the motor system and industrial plant. It also allows maintenance to be performed in a more efficient manner, since the course of action can be determined based on the type and severity of the fault.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.694-696
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• 2002

Transformers together with all equipment and accessories shall be designed and constructed to withstand the mechanical and thermal stresses produced by external short circuit which include three phase, single line-to-ground, double line-to-ground and line-to-line faults etc. Generally the Short Circuit Test of transformers is tested according to the ANSI/IEEE, IEC/JEC, KS etc, in domestic. In this study, it will be showed and compared the difference of symmetrical current for short circuit test of a Pad -mounted transformer according to with ANSI /IEEE and IEC.

• 전자공학회논문지A
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• 제31A권10호
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• pp.173-184
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• 1994

BiCMOS circuits mixed with CMOS and bipolar technologies show peculiar fault characteristics that are different from those of other technoloties. It has been reported that because most of short faults in BiCMOS circuits cause logically intermediate level at outputs, current monitoring method is required to detect these faluts. However current monitoring requires additional hardware capabilities in the testing equipment and evaluation of test responses can be more difficult. In this paper, we analyze the characteristics of faults in BiCMOS circuit together with their test methods and propose a new design technique for testability to detect the faults by logic monitoring. An effective method to detect the transition delay faults induced by performance degradation by the open or short fault of bipolar transistors in BiCMOS circuits is presented. The proposed design-for-testability methods for BiCMOS circuits are confirmed by the SPICE simulation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.36-37
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• 2016

The main cause of electrical fires are caused due to short circuit and open circuit. This is generates an instantaneous electric arc or spark accompanied with such electric faults. These arcs generate a pressed wire, contact badness, and a weakness in the wire coating etc.. This research proposes a protection circuit to prevent open-phase accident due to contact failure of electromagnetic contactor, tracking arc fault, open-phase within the three-phase electrical control panel which is the most commonly applied in the industry. The proposed circuit also alarms and cuts off of power system when electrical faults occurs. In addition, the proposed circuit is validated by various electric accident simulator.

• 전기학회논문지
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• 제58권5호
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• pp.929-935
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• 2009

As modem industrialized society progresses, the demand for electric power is increasing rapidly. The electric power system is getting amazingly bigger and complicated, which can easily induce serious troubles from the potential of large fault problems and/or system failure. The monitoring and diagnosis of the electric machine for the fault detection and protection has been important part in the electric power system. Most faults in the generator appear in the winding. This paper presents the air-gap magnetic flux characteristic of a small-scale 2-pole synchronous generator according to the faults in the field winding to protect the generator from the fault. The magnetic flux patterns in air-gap of a generator under various fault conditions as well as a normal state are simulated by using finite element method. These results are successfully applied to the detection and diagnosis of the short-circuit condition in rotor windings of a high capacitor generator.

• Journal of Power Electronics
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• 제15권4호
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• pp.1074-1084
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• 2015

These days, the widespread use of sensitive loads and distributed generators makes the solid-state circuit breaker (SSCB) an essential component in power circuits to achieve a high power quality for AC Grids. In traditional AC SSCB using SCRs, some auxiliary mechanical devices are required to make the reclosing operation possible before fault recovery. However, the proposed AC SSCB can break quickly and then be reclosed without auxiliary mechanical devices even during the short-circuit fault. Moreover, its fault current breaking time is short and its SSCB reclosing operation is fast. This results in a reduction of the economic losses due to fault currents and power outages. Through simulations and experiments on short-circuit faults, the performance characteristics of the proposed AC SSCB are verified. A design guideline is also suggested to apply the proposed AC SSCB to various AC grids.

• 한국화재소방학회논문지
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• 제23권3호
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• pp.40-47
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• 2009

오늘날 전기제품의 다양화, 대용량화와 더불어 전기화재의 발생이 점차 증가하고 있다. 반면 저압 배전계통에서 사용되고 있는 기존의 과부하겸용 누전차단기 즉, RCD의 저조한 응답특성으로 인한 전기화재 원인의 대부분을 차지하는 단락사고 및 과부하사고에 대한 대응이 매우 미흡한 실정이다. 이에 본 논문에서는 기존 RCD에 대한 모의 사고실험을 통하여 그 비신뢰성을 확인하고, 이러한 RCD의 단점을 개선하고자 고정밀 전류센서를 이용한 전기화재 방재장치를 제안하여 저압 배전계통에서의 단락 및 과부하사고로 인한 전기재해를 방지하고자 한다. 제안한 장치의 고정밀 전류센서로 사용된 리드스위치는 각종 전기사고에서 수반되는 단락전류 및 과전류에 의한 배전선로의 상승된 자속을 정밀 감지한 후, 자체 차단장치를 동작시키거나 또는 기 설치된 RCD를 신속히 차단시키는 이중 보호용 제어 동작원리를 가진다. 다양한 동작특성 분석을 통해 기존의 차단기와 비교하여 차단동작 응답속도와 신뢰성이 입증된다. 이로써 제안한 전기화재 방재장치는 기존 RCD들의 빈번한 오동작과 비신뢰성, 저조한 응답특성으로 인한 각종 전기사고 및 전기화재의 발생을 방지하고자 한다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권6호
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• pp.321-329
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• 2002

A protection scheme for series active compensator is presented and analyzed in this paper. The proposed series active compensator operated as a high impedance K($\Omega$) to the fundamentals when short-circuit faults occur in the power distribution system, and two control strategies are proposed in this paper The first is the method by detecting the fundamental source current through the p-q theory, the second is the method by detecting the fundamental component of load current in Synchronous Reference Frame(SRF). When the short-circuit faults occur in the power distribution system, the proposed scheme can protect the series active compensator without additional protection circuits. The validity of the Proposed Protection scheme was investigated through experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1350-1352
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• 1995

This paper discribed the characteristic of I-t cross-over-point between current limited-fuse and explusion fuse(Bay-O-Net Fuse) and fuse protection in pad-mounted transformer that was generated internal faults and the short circuit of secondary side(load side). In the I-t cross-over-point, current limited fuse was melted when transient recovery voltage was raised rapidly.

• Journal of Power Electronics
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• 제11권5호
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• pp.759-766
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• 2011

This paper focuses on monitoring and predicting the short circuit faults of the rotor windings of large turbo-generator systems. For the purpose of increasing efficiency and decreasing maintenance cost, a method that combines the HHT (Hilbert Huang Transform) with a wavelet has been studied. This method is based on analyzing a classical Albright detecting coil. Due to the Empirical Mode Decomposition (EMD) and the Intrinsic Mode Functions (IMF) of the HHT the exact location of a short circuit of rotor windings may be given. However, a part of the useful information is eliminated by the unreasonable decomposing scale of the wavelet. Based on the thermodynamics modeling method, this study was illustrated with a 50MW turbo-generator system that is installed in Northern China. The analysis results, which have very good agreement with those of a previous study, show that the method of combining the HHT with a wavelet is an effective way to analyze and predict the short circuit faults of the rotor windings of large generators, such as supercritical turbo-generator systems and wind turbo-generator systems. This work can offer a useful reference for analyzing smart grids by improving the power quality of a distribution network that is supplied by a turbo-generator system.