• 한국마린엔지니어링학회:학술대회논문집
• /
• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
• /
• pp.304-309
• /
• 2005

This paper presents an electronic ballast using a step down converter, a low frequency inverter for high intensity short-arc discharge lamp. The proposed ballast is composed of a full-wave rectifier, a step down converter operated as a current source with power regulation and a low frequency inverter with external ignition circuit. The ignition circuit generates high voltage pulse of $3{\sim}5[kV]$ peak, 130[Hz] periodically. Moreover, it is able to reignite at regular intervals by protective circuit. As experimental results on the test, acoustic resonance phenomenon is eliminated by operating the low frequency square wave voltage and current. Lamp voltage, current and consumption power are measured 123.8[V], 8.1[A] and 1,002[W], respectively. It was confirmed that the designed ballast operate the lamp with a constant power.

• 전력전자학회논문지
• /
• 제3권4호
• /
• pp.426-436
• /
• 1998

Identification of fault current during the operation of a power semiconductor switch and activation of suitable remedial actions are important for reliable operation of power converters. A short circuit is a basic and severe fault situation in a circuit structure such as voltage source converters. This paper presents a new active protection circuit for fast and precise clamping and safe shutdown of fault currents of the IGBTs. This circuit allows operation of the IGBTs with a higher on-state gate voltage, which can thereby reduce the conduction loss in the device without compromising the short circuit protection characteristics. The operation of the circuit is studied under various conditions, considering variation of temperature, rising rate of fault current, gate voltage value, and protection circuit parameters. An evaluation of the operation of the circuit is made using IGBTs from different to confirm the effectiveness of the protection circuit.

• 대한전기학회논문지
• /
• 제39권5호
• /
• pp.453-461
• /
• 1990

In this paper, a short primary-short secondary single-sided linear induction motor which is used as the driving source for an automatic conveyor system, is selected as an analysis model. The finite element method in which the current vector potential is introduced is adopted to analyze the eddy current distribution and thrust force which are produced according to the relative position of the primary and the secondary. Also, the analysis results are compared with experimental ones, to show the propriety of this model.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
• /
• pp.501-502
• /
• 2006

In this paper, new and aging sample of MCCB and ELCB are investigated the main performance test such as short circuit test, mechanical and electrical endurance test, dielectric test and surge current test. The surface conditions of new and aging sample are analyzed by SEM, TGA and DSC. The ELCB occurred badness mainly in short circuit test and surge current test. The badness cause of short circuit test was confirmed due to imperfect contact of contact part.

• 한국정보전자통신기술학회논문지
• /
• 제5권4호
• /
• pp.211-215
• /
• 2012

대형의료기기는 환자 진단과 치료 행위에 있어서 매우 중요한 기기이다. 이런 대형의료기기를 사용하여 환자를 진단 또는 치료할 때 의료기기의 회로 내에서 갑작스런 전류의 변화는 회로의 단락 등 매우 심각한 문제를 일으킨다. 특히 회로 내에서 전류변환기에 큰 부하가 걸리게 한다. 이것으로 인해 변환기는 포화에 이르게 되는데 이것은 철심코일 인턱터의 magnetic curve에 기인한다. 이와 같이 변환기가 saturate에 이르게 되면 1차 측과 2차 측의 변환 비율이 깨지게 되고 회로가 단락되는 문제가 발생하게 된다. 이 논문 에서는 대형의료기기에 사용되는 current 변환기의 입력 측에 갑작스런 큰 전류 변화가 발생 했을 때 일어나는 그에 따른 포화 상태와 그의 2차 측 전류의 변화를 simulation 해본다.

• 한국안전학회지
• /
• 제28권4호
• /
• pp.38-42
• /
• 2013

This study performed the quantitative distribution analysis of created voids to an insulator when applying general flame and DC short-circuit current to 2.5 $mm^2$ HIV (600 V Grade Heat-Resistant Polyvinyl Chloride Insulated Wires). The diameter of cross-section of HIV normal product and the radius of conductor were measured to be 3.3 mm and 1.8 mm. The exterior of HIV exposed to general flame showed severe carbonization and its interior exhibited voids created by dechlorination reaction. This study observed the characteristics that, when the shortcircuit current applied for 2 seconds from a DC 12 V lead battery, the conductor and neighboring insulator were melted, causing the insulator adhering to the conductor. On average, 87 voids were created on 10 mm of the HIV. The average diameter of voids was 0.25 mm. In addition, it was found that, when the short-circuit current applied for 4 seconds, the interior of insulator in contact with conductor severely carbonized and showed exfoliation phenomenon. On average, 47 voids were created, with more voids at the bottom. The average diameter of voids was 0.20 mm. When the short-circuit current for 6 seconds, most parts of upper part of conductor was carbonized, 20 voids were created. The average diameter of voids was measured to be 0.24 mm. It could be seen that the created voids received little influence by the type of energy source and the number of created voids was reduced as the energy supply time increased.

• Journal of Pharmaceutical Investigation
• /
• 제35권2호
• /
• pp.81-87
• /
• 2005

We have prepared karaya gum patches containing ketoprofen and investigated the effect of short-time current pretreatment of skin on the permeability. Hairless mouse skin was treated with current before the patch was mounted on the skin. The effect of current density and current duration on the flux of ketoprofen was studied. The possibility of additive effect with penetration enhancer (PGML) was also investigated. Iontophoretic pretreatment of skin increased the passive flux up to 3 folds at 0.4 $mA/cm^2$ current density, when the matrix contained no PGML. As the duration of current-pretreatment and current density increased, flux increased. PGML increased the average passive flux markedly, about 6 to 12 folds, depending on the concentration in the patch. Current pretreatment further increased the flux from this PGML containing patch, exhibiting additive effect. These results indicate that short-duration current pretreatment of skin can be an useful method for the enhancement of ketoprofen permeability through skin.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 A
• /
• pp.455-457
• /
• 2003

In the present IEC 60427(2000), reduced applied voltage can be used for synthetic short-circuit making current tests if the maximum pre-arcing time of the test circuit breaker is less than $1/{\omega}$. But in the near future IEC, only the making tests with full test voltage shall be allowed. To meet this trend, KERI is preparing synthetic making test facilities using step-up transformer, ITMC and plasma making switch. This paper presents analytical characteristics of KERI's synthetic short-circuit making test circuits. The results of this paper can be useful for effective and adequate tests.

• Journal of Electrical Engineering and Technology
• /
• 제7권5호
• /
• pp.778-783
• /
• 2012

The synthetic short-circuit making test to adequately stress the circuit breaker has been specified as the mandatory test duty in the IEC 62271-100. The purpose of this test is to give the maximum pre-arcing energy during making operation. And this requires the making operation with symmetrical short-circuit current that is established when the breakdown between contact gap occurs near the crest of the applied voltage. Also, if the interrupting chamber of circuit breakers is designed as the type of common enclosure or the operation is made by the gang operated mechanism that three-phase contacts are operated by one common mechanism, three-phase synthetic making test is basically required. Therefore, several testing laboratories have developed and proposed their own test circuits to properly evaluate the breaker performance. With these technical backgrounds, we have developed the new alternative three-phase making circuit.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제54권1호
• /
• pp.27-32
• /
• 2005

This study presents an analysis technique that can consider all variables which are needed in the design of short circuit current capability of electrical contacts. Required variables in the design are material of contact, contacting area, applied force, asperity of surface, current and so on. Short circuit current capability test was carried out for the interrelation of design variables and the verification of analysis technique. Temperature rise equation of the contacts was obtained from the test results, and also, a standard that is criterion of the occurrence availability of melting or spot of contact surface from test results was established.