• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.5
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• pp.60-67
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• 2003

The goal of this paper is to improve EMC performance of circuit breaker. Circuit breaker and control cubicle are interconnected by multi control cable. Also many control cables are laid on each apparatus. These control cables are directly connected by electronic components. So control cables are very important to improve EMC performance of circuit breaker. This paper suggests installing a ground conductor in parallel(PGC) to control cables. Also this paper suggests using shielding cables as secondary cables of voltage transformer in circuit breakers, and grounding both ends of shielding. After applying suggested methods, we verified EMC performance of circuit breaker is improved.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.3
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• pp.120-125
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• 2002

The switching-mode power converter has been widely used because of its features of high efficiency and small weight and size. These features are brought by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI(Electromagnetic Interference) which deteriorate the reliability of the converter themselves and entire electronic systems. This problem on the surge and noise is one of the most serious difficulties in AC-to-DC converter. In the switching-mode power converter, the output voltage is generally controlled by varying the duty ratio of main switch. When a converter operates in steady state, duty ratio of the converter is kept constant. So the power of switching noise is concentrated in specific frequencies. Generally, to reduce the EMI and improve the immunity of converter system, the switching frequency of converter needs to be properly modulated during a rectified line period instead of being kept constant. Random Pulse Width Modulation (RPWM) is performed by adding a random perturbation to switching instant while output-voltage regulation of converter is performed. RPWM method for reducing conducted EMI in single switch three phase discontinuous conduction mode boost converter is presented. The more white noise is injected, the more conducted EMI is reduced. But output-voltage is not sufficiently regulated. This is the reason why carrier frequency selection topology is proposed. In the case of carrier frequency selection, output-voltage of steady state and transient state is fully regulated. A RPWM control method was proposed in order to smooth the switching noise spectrum and reduce it's level. Experimental results are verified by converter operating at 300V/1kW with 5%~30% white noise input. Spectrum analysis is performed on the Phase current and the CM noise voltage. The former is measured with Current Probe and the latter is achieved with LISN, which are connected to the spectrum analyzer respectively.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.3
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• pp.130-137
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• 2015

This study is about the controller development of the Electric Operating Cell(EOC) which will replace the Mechanical Operated Cell(MOC) of the vacuum circuit breaker which has been used in the power plant and the performance test for the developed controller. The controller developed through this study was manufactured considering the harsh installation environment and electrical condition of the power plant, and the controller performance certification test for confirming the product reliability was taken to know whether or not to withstand fully in various electrical and mechanical problems. Items for performance certification test were AC power frequency voltage withstand test, combined surge immunity test, 1 [MHz] oscillatory SWC test, fast transient SWC test, radiated electromagnetic interference test, vibration test. As a result, all tests has passed an examination without malfunction.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.12
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• pp.1726-1731
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• 2014

This paper shows the developed new lightning arrester LCM (Leakage Current Measuring device) which is important element of GIS (Gas Insulated Switchgear) Preventive & Diagnostic system and verify its performance though strengthened test standards. The existing lightning arrester LCM was modified to solve measuring errors which happened frequently. At first, we explained the principle of measuring leakage current. Through analyzing some problems which the existing LCM have. we got some improvable items. For the performance verification of the improved LCM, we manufactured prototype LCM which is applied some improvable items such as improving LCM circuit, adding protection circuit, optimizing inner structure of LCM and changing ground design. After then we carried out the performance test. Accredited testing laboratory carried out the performance verification test according to performance test criteria and procedure of reliability test standards, IEC-60225, 61000 and 60068 etc. We confirmed the test results which correspond with the performance test criteria. Also, we confirmed the performance of the improved LCM installed & being operated at G Substation through the immunity test against the normal noise and open/close surge etc.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.61-62
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• 2017

In this study, we introduce some main functions and specifications of a recently commercialized potable compact high voltage generator. USB killer has been designed to test surge protection circuitry of electronic equipments using USB ports. USB killer transforms 5V DC power supplied by USB port into a sufficiently high voltage over 200V DC through oscillator, transformer, voltage multiplier, and rectifier. The power charged in a high-capacity condenser can be applied back into the electronic equipments as an electric shock to destroy them or test protection circuits. USB killer is a readily available item, and one can test a variety of electronic equipments. We introduce some test results known over the internet and those obtained from our tests.