• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1079-1081
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• 1998

This paper describes the dissipation factor measuring device for insulating oil in operating pole transformer by DSP(digital signal processor). After applying voltage to the sensor which is installed in a transformer, acquire source voltage and current of sensor using FFT techniques, then we could evaluate the dissipation factor of insulating oil. To improve measuring accuracy and processing speed, we use TMS320C31 DSP, FFT and data analysis techniques. Also we suggest deterioration criterion of insulating oil and compared the developed diagnosis device with schering bridge on deteriorated insulating oil. The result of this paper show that the developed measuring device can be used as diagnosis device for the pole transformers.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.533-534
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• 2007

This paper investigates impulsive noise from a pole transformer in low voltage distribution system for power line communication. EMI noise from the pole transformer is indicated from the experiment. The noise has certain characteristics because it is caused by partial discharge. The noise level is above -35dBm without a filter. Therefore, the filter which is made of ferrite is used in order to eliminate the noise. the noise filters should be applied to both the phase line and the neutral line. Otherwise, It is likely to have little overall impact on elimination of noises. the performance of filter is verified with various experiments. In conclusion, the equivalent circuit of power line communication including noise source is described as a lumped circuit.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.607-612
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• 2002

This paper presents the first domestic model product of hybrid Insulation low-loss type pole transformer, with increased overload ability, increased life, reduced loss, focusing improved short-circuit characteristics. The capacity of this transformer is 100 KVZ, rates first voltage 13200 V and secondary voltage 230/115 type. The volume of model transformer that was produced in high temperature using hybrid insulation can be reduced to 10-20% in comparison with that of present transformer with the same capacity. In this paper, we did short-circuit test and tested general characteristics of model transformer. In addition, we suggested design application new concept and methods thorough this experiment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.125-129
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• 2004

The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss, but it needs some cooling method because heat radiation between each winding is difficult. The life of transformer is significantly dependent on the thermal behavior in windings. Many transformer designers have calculated temperature distribution and hot spot point by FEM(finite element method) to analyze winding temperature rise. In this paper, the temperature distribution and thermal stress analysis of 100kVA pole cast resin transformer for power distribution are investigated by FEM program.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.7
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• pp.84-93
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• 2007

The pole transformer is one of the most important facility to insure the stability of electric power supply. which distributes electricity to customers directly. However there are a lot of defects which are caused by manufacturing fails(in 3 years) or deterioration (in 13 years), so we need a more improved transformer which insures quality. This thesis talks about the development of the new-type transformer using the hybrid insulation that is durable thermally, mechanically, and electrically. It would show how to lay out and produce the transformer using the hybrid insulation. And finally we are sure that we could increase the utilization rate of a transformer by 160% as compared with its own capacity through the overload test. Also, we carried out the examination about the short-circuit and insulation with a 100[kVA] model transformer, so that we expound the analysis of magnetic-mechanical forces intensity and the measure for improving short-circuit efficiency.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.921-922
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• 2007

In recent years, environmental concerns have been raised on the use of poorly biodegradable fluids in electrical apparatus in regions where spills from leaks and equipment failure could contaminate the surroundings. For development of the environmental-friendly pole transformer using vegetable oil, we discussed the insulation construction of the transformer and the dielectric characteristics of the Nomex insulation paper in vegetable oil. Based on the experimental data, the insulation of the transformer is designed.

• JOURNAL OF ELECTRICAL WORLD
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• no.4 s.112
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• pp.19-23
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• 1986

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.270-272
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• 1996

This paper describes the dissipation factor measuring techniques of insulating oil on operating pole transformer by using digital signal processor. After applying voltage to the electrodes which is installed in a transformer, acquiring source voltage and current of electrodes and using cross-correlation techniques, we can check the dissipation factor of insulating oil. To improve measuring accuracy and the speed of process, we use hardware such as TMS320C31 DSP board and software such as cross-correlation techniques and rectangular window techniques. We simulated the measuring accuracy and the degree of the noise effect of this new measuring techniques by using computer simulation, and compared the simplified measuring devices with schering bridge on degraded insulating oil. The result showed that this measuring technique can be used as diagnostic method on the pole transformers.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1811-1813
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• 2001

In order to obtain the useful data for quality control of the pole transformer and supply the stable electric power in distribution line, The evaluation of performance for low-loss pole transformer had been performed for new products and ones under operation for several years in distribution line. As the results, we found that the rate of fail were very high in gaskette, short-circuit strength and temperature-rise test, especially 48 percent in gaskette test.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.5
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• pp.67-72
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• 2011

In this study we investigate the background of UPS output transformer(${\Delta}-Y$) operation on neutral ungrounded system, and perform field experiment of neutral floating-phenomenon for the inter-locked securing of electric facilities and improvement of neutral floating-phenomenon. Experiment results show that a floating-phenomenon occurs when four-pole input-breaker trip and the neutral to earth voltage occurring concurrently is identified as phantom voltage. And the measures for the transient overvoltage that can occur in floating-state also are investigated. As a result, the risk elements of neutral ungrounded method as well as neutral floating-phenomenon are removed by installation of separate solidly-grounded transformer and switching four-pole input-breaker to three-pole input breaker.