• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2084-2090
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• 2007

The DGA (Dissolved Gases Analysis) technique has been widely using for fault diagnosis of the power transformers. Some electric power utility company establishes the criteria of DGA to improve reliability, because of difference of operation environment and design of power transformer. In this paper, we introduce intelligent diagnosis system for DGA result of KEPCO (Korea Electric Power Cooperation). This system can classify patterns type of gases ratio that frequently occurs in recent result of gases analysis using Fuzzy Inference. The classification of Patterns let us know that major causes of gases generation based on type of patterns. Finally, Neural Network based on patterns diagnose transformer. NN was trained using result data of DGA of actually faulted transformers recently. Result of intelligent diagnosis system is right well in comparison with actual inner inspection of transformers.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.138-139
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• 2008

An iron-cored voltage transformer(VT) is usually used to obtain the standard low voltage signal for protection and measurement. Generally, the iron-cored transformers have errors due to the hysteresis characteristics of the iron-core. An error compensating algorithm for iron-cored instrument transformer can improve the accuracy of conventional voltage transformers. This paper describes the iron-cored electronic voltage transformer having the error compensating algorithm. The innovative product composes an iron-cored VT and an intelligent electronic device(IED) having the error compensating algorithm. The test results of the iron-cored electronic voltage transformers in Korea Electro-technology Research Institute(KERI) are presented.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.6 no.4
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• pp.53-59
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• 1992

This paper describes an instrument for the detection and geometric location of partial discharge (PD) source in transformers. This instrument measures electric current pulses and ultrasonic pulses simultaneously, counts the number of electrical pulses and determines the geometric location of PD in transformers. It was found that there is a relationship between partial discharge magnitude and pulse repetition rate when the applied test voltage and oil temperature were varied. Through the laboratory test using model transformer, it was clarified that this detector could be used for detecting and locating PD in the transformer.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.1
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• pp.82-86
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• 2012

High-capacity high-voltage pulse generator that can be used for environmental clean-up was developed using transformers. High-voltage pulse is consists of the primary wave and the harmonic wave which are increased as a series circuit using transformers to make pulses. Each transformer has a band-pass characteristics. The output voltage of the pulse width 50[%] was decided. The output voltage of high-voltage pulse generator device was measured as 1.4[kV] (Peak-to-Peak).

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.701-706
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• 2002

Typically, dimensions of the power circuit depend on magnetic components, heat sink, and smoothing capacitor, etc. For the miniaturization of the power circuit, one of the solutions is that bulky magnetic transformer in previously used is replaced by a piezoelectric transformer. Therefore, since many systems are attempted to apply the piezoelectric transformers, a new piezoelectric material is tending to be developed continuously. In this paper, an analysis of neon tube inverters with piezoelectric transformers are presented by Pspice modeling. Simulation results show that it is possible to apply a piezoelectric transformer to neon tube inverters with high conversion efficiency

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.370-373
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• 2002

A new phase shift full bridge converter(PSFB) with serially connected two transformers is proposed. It is well suited for applications in the communication equipment of a few hundred watts. The main features of the proposed converter are a wide input voltage range, an easiness to meet the requirement for zero voltage switching (ZVS) condition at a light load, and a small output voltage ripple. Furthermore, it features high power density since serially connected two transformers can replace both a main transformer and an output inductor. A mode analysis and experimental results are presented to verify the validity of the proposed converter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.203-207
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• 2002

In order to evaluate the aging of mineral oil immersed distribution transformers, it gathered some insulation oil in over loaded and long time(exceed their service life, 13yrs.) aged transformers in the field, we measured moisture content, acid number, dielectric strength of the oil as defined in KS C 2101 standard. And also, it had been measured dielectric constant, specific resistant, $tan{\delta}$ on aged transformer oil at from $10^{\circ}C$ to $130^{\circ}C$. These results are compared with a new mineral oil. From this study, it can be considered that the analysis of mineral oil may be suitable for evaluation of life expectancy in distribution transformers

• Journal of Power Electronics
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• v.18 no.3
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• pp.902-909
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• 2018

This study investigates the influences of different core parameters on the dynamic performances, such as rise time and overshoot, in pulse transformers for the triggering circuit of SCRs. First, a simplified transformer equivalent circuit, which emerges from a standard transformer equivalent circuit, is developed to analyze the step response. Second, the relations between the dynamic performances and the parasitic parameters are calculated by the simplified equivalent circuit. Third, the variations of rise time and overshoot, which are vital to the stability of triggering SCRs, with different core parameters, such as mechanic dimensions and topologies, are comprehensively investigated by analyzing the parasitic parameters. Finally, prototype transformers are fabricated to experimentally validate the analysis. The presented method can practically instruct the design of a pulse transformer for triggering SCRs.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.279-282
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• 1990

This paper describes an nstrument for the detection and geometric location of partial discharge(PD) sources in transformers. This instrument measures electric current pulses and ultrasonic pulses simultaneously, counts the number of electrical pulse and determines the geometric location of PD in transformers. It was found that there is a relationship between partial discharge magnitude and pulse repetition rate when the applied test voltage and oil temperature were varied. Through the laboratory test using model transformer, it was clarified that this detector could be used, satisfactory for detecting and locating of PD in the transformer.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1737-1739
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• 1997

We describe the characteristic of LVI test system and methods to detect the deformation of windings in the power transformers. As the front rise time of recurrent-surge generator pulse less than 1000ns and the peak value of pulse is about 500V, we have the good results of detecting winding deformation in the LVI test of transformer. And we discuss the application of LVI test method and the condition of RSG pulse through results of in one and three pole transformers under Lab. tests.