• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권11호
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• pp.587-596
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• 1999

The use of Switching elements in power systems causes the current or voltage to involve harmonic waves. Harmonics bring about registration errors of the equipment for measuring power. In case the induction watthour meter designed on sinusoidal source is used in the measurement of power with harmonics, the precise measurement of power has many problems because harmonics cause a decrease of power factor and vibration by the unstable driving force on the aluminum disc. In this paper, analysis and test results on the harmonic sensitivity of an induction watthour meter is reported when the input voltage and current with harmonics were supplied to single-phase watthour meter.

• 한국전기전자재료학회논문지
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• 제31권4호
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• pp.261-266
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• 2018

When the clamp meter approaches the electric path where current is flowing, leakage current can be measured at a distance from the electric current because the induced current increases as the magnitude of the current increases and approaches nearer to the electric path. Therefore, measurements were carried out from a distance to avoid this effect. In addition, the measured values differ depending on the location of the power line that penetrates the ZCT of the clamp meter, thus measurements were performed at a location where this effect was minimized. The fraction of compliant branch circuits, whose leakage current was lower than 1.00 mA, was found to be 69.0% out of the total of 439 branch circuits, while the percentage of compliant branch circuits having an insulation resistance higher than $0.20M{\Omega}$ was found to be 93.2%. The reason why the percentage of compliant branch circuits with low leakage current was low might be due to the inclusion of capacitive leakage current in the total measured leakage current.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.155-158
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• 2001

In this paper, the Load Current Observer Design for 3-phase Voltage Type PWM Converter with DC Meter Load. The sinusoidal input current and unity input power factor are realised based on the estimated source voltage performed by the Load Current Observer using actual currents and DC link voltage.

• 전기학회논문지
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• 제63권5호
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• pp.713-718
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• 2014

DC urban railway power system consists of DC power network and AC power network. The DC power network supplies electric power to railway vehicles and the AC power network supplies electric power to station electric equipment. Recently, because of power consumption reduction and peak load shaving, intelligent measurement of regenerative energy and renewable energy adapted on DC urban railway is required. For this reason, DC smart metering system for DC power network shall be developed. Therefore, in this paper, DC voltage sensor, current sensor, and DC smart meter were developed and evaluated by performance test. DC voltage sensor was developed for measuring standard voltage range of DC urban railway, and DC current sensor was developed as hall effect split core type in order to install in existing system. DC smart meter possesses function of general intelligent electric power meter, such as measuring electricity and wireless communication etc. And, DC voltage sensor showed average 0.17% of measuring error for 2,000V/50mA, and current sensor showed average 0.21% of measuring error for ${\pm}2,000V/{\pm}4V$ in performance test. Also DC smart meter showed maximum 0.92% of measuring error for output of voltage sensor and current sensor. In similar environment for real DC power network, measuring error rate was under 0.5%. In conclusion, accuracy of DC smart metering system was confirmed by performance test, and more detailed performance will be verified by further real operation DC urban railway line test.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.25-27
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• 1997

The precise measurement of consumed power for a given time is very important in the energy management aspect. Up to days, most power meter has been used and designed for use on circuits in which the voltage and current are essentially sinusoidal. Recently the increase of switching element in power system causes the current and voltage with harmonics. Therefore, power energy involving harmonics is supplied to the system and the error of power measurement of watthour meter is existed. In this paper, we present a characteristic analysis by input frequency variation and analytical basis of induction watthour meter considering harmonics.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.58-60
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• 1998

The precise measurement of consumed power during the given time is very important in the energy management aspect. Up to days, induction watthour meter has been designed for use in the alternating circuits in which the voltage and current are essentially sinusoidal. The use of switching elements in power system causes the current or voltage involving harmonics. Therefore the registration error is caused by harmonics in the equipment for measuring power. This paper presents the registration error of the induction watthour meter in the presence of harmonic distortion. The accuracy of a watthour meter on loads in which the input source is not sinusoidal is investigated. And the effects of individual harmonic are reported by experiment.

• Journal of Magnetics
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• 제8권4호
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• pp.160-163
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• 2003

In magnetic flux measurement, output voltage drift of electronic integrator is an essential problem. In this work, we have developed a new kind of Miller type integrator using a sample and hold amplifier. Input bias current was measured and this value was hold in the sample and hold amplifier, after that input bias current of Miller integrator was compensated automatically using the value which holds in the sample and hold amplifier. Developed flux-meter shows the drift of flux-meter are smaller than 10$^{-5}$ Wb/min in full scale of 10$^{-2}$, and we could also measure multi-channel magnetic flux simultaneously.

• 한국자기학회지
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• 제15권6호
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• pp.332-335
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• 2005

자속계의 경우 입력전압을 적분하여야 되기 때문에 연산증폭기의 입력 바이어스 전류가 있으면 적분기의 출력이 드리프트하게 된다. 본 연구에서는 이 드리프트를 자동으로 측정하고 보상하기 위하여 전압변동이 없는 디지털 sample and hold증폭기를 자속계에 도입하여 제작하였다. 개발한 자속계의 경우 적분기의 시간상수 $RC=10^{-3}$ s에서 드리프트가 $5{\times}10^{-8}\;Wb/s$ 이하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.860-863
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• 2003

In this paper high power SMU(Source Measurement Unit) having 50V/1.5A source/measure range has been designed and implemented. The SMU has two operation mode, voltage mode and current mode. The SMU can be used as variable voltage source, variable current source, voltage meter, or current meter. Combining two different unit, output power can be doubled as 100V/1.5A. The developed SMU tan be used many semiconductor testing system and electronic device inspecting system.

• Progress in Superconductivity
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• 제3권1호
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• pp.130-133
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• 2001

A multifilamentary Bi-2223 HTS tape for superconducting power applications was studied through the fabrication of 250-meter long tapes by the PIT(powder in tube) process. To fabricate continuous long wire, a drawing machine, a two-drum bull block and a rolled tape winding machine were developed. Especially, 250-meter long tapes were heat treated in the shape of pancake coil to reduce the heat affect zone and to achieve the high critical current. Engineering critical current density was improved through both the enhancements of critical current density by control of thermal process and the increase of filling factor by using thin Ag alloy sheath tubes less than 1.5 mm in thickness. We have made successfully 250-meter long 37 filamentary tapes with high filling factor up to 31 % employing the modified drawing and rolling technique. The critical current of 250-meter long tapes with pancake coil type was measured by transport method at self-field up to 250 gauss of center field. The measured values, based on the transport critical current at self-field, $I_{c}$ -B characteristics and magnetic field analysis, are 34 A of I$_{c}$ and 4.0 $kA/\textrm{cm}^2$ of $J_{e}$ at 250 m, 77 K, and 0 T. We also have achieved the 56 A of I$_{c}$ and 7.0 $0 kA/\textrm{cm}^2$ of$ J_{e}$ in short tapes at 77K, self-field, and 1$mutextrm{V}$/cm.