• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.6
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• pp.619-625
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• 1991

Phenomena of streaming electrification of insulting oil(T.O) is studied where the oil is contacted with solid insulating materials when it is pumped through a circulating system in a large power transformer. The leakage current, the electrical potential at the neutral terminal point of the transformer and the surface electrical potential of the oil are investigated. And the leakage current from the neutral terminal point is measured as a function of a bias polarity applied to a transformer case to investigate the polarty of ion which is absorbed in the case at the interface between the case and oil. As a result, it is found that insulating materials, and it is suggested that the leakage current is the sum of the relaxation current by positive charge from insulating oil to the neutral terminal point and by electrification current from negative charge electrified by the contact with solid insulating materials.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.37-39
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• 2003

This paper Presents an effective modeling scheme of high temperature superconducting transformer. So far there were numerical modeling and designs for conventional transformers for various applications. Recently, the interest and the R&D in superconducting technology and devices such as superconducting generator, motor, cable, fault current limiter and transformer have been increased gradually. With those interests, this paper proposes a simulation model of high temperature superconducting transformer using PSCAD/EMTDC, which can be applied to the utility network simulation readily under various system conditions.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.95-97
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• 2007

Transformer inrush current can cause the voltage drop by source impedance. The accurate modeling and analysis for inrush current is first step to limit the inrush current and improve the power qualify. This paper presents the modeling of transformer inrush current by EMTP-RV using Jeju power system, Korea. The method to model the hysteresis curve of transformer in EMTP-RV is discussed. Simulations demonstrate the verification of modeling of inrush current by comparing the data recorded in field with simulation values and analyzing the harmonics of inrush current.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.2
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• pp.180-191
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• 2003

In this paper, the modelings of PSPICE of the piezoelectric transformer and CCFL drive circuit using an electrical equivalent circuit is proposed. In the CCFL drive circuit modeling the model parameters of the CCFL were derived using the method of least squares because push-pull inverter and loads such as CCFL were also modeled using PSPICE. It is considered that the simulation techniques can be used in the piezoelectric devices such as piezoelectric transformer.

• Proceedings of the KIEE Conference
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• 2000.11a
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• pp.136-138
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• 2000

This paper describes an efficient location detection algorithm for a partial discharge(PD) source in the transformer. The algorithm is previously proposed is not suitable for PD source detection because ultrasonic signal is diminished through the inner structure. In this paper, the proposal algorithm find PD source using geometry method and 3th sensor on the one side of transformer without diminution of ultrasonic signal. The proposed algorithm demonstrates the effectiveness and validity on model transformer.

• Journal of Environmental Science International
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• v.21 no.5
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• pp.573-578
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• 2012

In this study, adsorption of polychlorinated biphenyls(PCBs) in transformer oil on powder activated carbon (PAC) and synthetic zeolite was evaluated. Adsorption characteristics of PCBs on the PAC and zeolite has been investigated in a batch system with respect to adsorbents amount and contact time. BET results showed 908 m2/g for PAC and 483 m2/g for zeolite. The adsorption capacity of PCBs increased with an increasing input amount of absorbent. The adsorption experimental results showed that PAC removed 90% of input PCBs in transformer oil while zeolite removed only 64%. Adsorption of PCBs to PAC and zeolite fit the Freundlich model well. The Freundlich parameter, Kf, for PAC and zeolite was 193.1 and 43.0 respectively, indicating that PAC is effect adsorbent for PCBs adsorption in transformer oil.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.216-216
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• 2011

There have been various direct or indirect methods to measure the characteristics of plasma. Comparing to direct method like Langmuir probe method, indirect measurements which give information as some external parameters like current, voltage, or phase are easier to obtain. In this research, an indirect method to measure averaged plasma density in a transformer coupled plasma(TCP) has been proposed and evaluated. With a simple analytic model connecting electrical characteristics to plasma impedance, direct measurement via double Langmuir probe has been performed. This result may play a meaningful role to diagnose TCP or similar plasma sources

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.1
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• pp.7-12
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• 1999

In this paper, the analytical results on the maximum temperature rise estimation, taking account of the magnetizing current, are presented. Magnetizing current effects are considered for the maximum temperature rise estimation during quenches. By introducing the first order model of the infinite solenoids, we calculate the magnetizing and leakage inductances of the coaxial-wound-superconducting transformers. As the permeability of the transformer core increases, so does the magnetizing inductance, while the leakage inductances and the magnetizing current of the transformer go down. These varying permeability effects on maximum temperature rise estimation is applied to the superconducting transformers, of which specifications have already been published. The calculated results showed sufficient margins to the thermal damage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.270-273
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• 1996

This paper describes a type of piezoelectric transformer with improved design principles. It consists of a thin rectangular piezoelectric ceramic plate having two input electrodes and one output electrode. The length of each input and output electrode is nearly one third of that of piezoelectric transformer itself. In the driving section, the ceramic plate is poled in the thickness direction reversely with each other, and has electrodes on both main faces. The electric input near its fundamental resonance frequency is applied to the driving section in parallel and the output voltage from the generating section is connected to the resistor load. Its equivalent circuit is derived from the Mason\`s model. The frequency characteristics near the resonance frequency under no load have been investigated. Moreover, using this piezoelectric transformer we measured the LCD backlight characteristics.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.216-218
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• 1994

This paper established on vibration model of transformer winding caused, mainly, by load current. We considered the rotations between loads and vibration amplitudes by changing load current in constant temperature and voltage, to get the modeling of transformer winding vibration. Equation between loads and vibration signal's amplitudes using LS approximation mode it possible to predict a vibration signal's amplitude at any load. With this equation, we arc willing to establish the basis data for power transformer diagnosis.