• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.391-394
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• 2009

In this paper, achieved rise temperature distribution about degradation phenomenon of 2 MVA distribution mold transformer using finite element method (FEM). Usually, life of transformer is depended on temperature distribution of specification region than thermal special quality of transformer interior. Specially, life of transformer by decline of dielectric strength decreases rapidly in case rise by strangeness transformer interior hot spot temperature value permits. Because calculating high-voltage winding and low-voltage winding of mold transformer and Joule's loss of core for improvement these life, forecasted heat source, and high-voltage winding and low-voltage winding of mold transformer and rise temperature distribution of core for supply of electric power and temperature distribution of highest point on the basis of the result Also, calculated temperature rise limit of mold transformer and permission maximum temperature using analysis by electron miracle heat source alculate and forecasted rise temperature distribution by heat source of thermal analysis with calculated result.

• Journal of Electrical Engineering and Technology
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• v.7 no.3
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• pp.312-319
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• 2012

The life of a power transformer is dependent on the life of the cellulose paper, which influenced by the hot spot temperature. Thus, the determination of the cellulose paper's life requires identifying the hot spot temperature of the transformer. Currently, however, the power transformer uses a heat run test is used in the factory test to measure top liquid temperature rise and average winding temperature rise, which is specified in its specification. The hot spot temperature is calculated by the winding resistance detected during the heat run test. This paper measures the hot spot temperature in the single-phase, 154kV, 15/20MVA power transformer by the optical fiber sensors and compares the value with the hot spot temperature calculated by the conventional heat run test in the factory test. To measure the hot spot temperature, ten optical fiber sensors were installed on both the high and low voltage winding; and the temperature distribution during the heat run test, three thermocouples were installed. The hot spot temperature shown in the heat run test was $92.6^{\circ}C$ on the low voltage winding. However, the hot spot temperature as measured by the optical fiber sensor appeared between turn 2 and turn 3 on the upper side of the low voltage winding, recording $105.9^{\circ}C$. The hot spot temperature of the low voltage winding as measured by the optical fiber sensor was $13.3^{\circ}C$ higher than the hot spot temperature calculated by the heat run test. Therefore, the hot spot factor (H) in IEC 60076-2 appeared to be 2.0.

• Journal of Electrical Engineering and Technology
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• v.8 no.1
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• pp.156-162
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• 2013

This paper measures the hot spot temperatures in a single-phase, 154 kV, 15/20 MVA power transformer filled with natural ester fluid using optical fiber sensors and compares them with those calculated by conventional heat run tests. A total of 14 optical fiber sensors were installed on the high-voltage and low-voltage windings to measure the hot spot temperatures. In addition, three thermocouples were installed in the transformer to measure the temperature distribution during the heat run tests. In the low-voltage winding, the hot spot temperature was $108.4^{\circ}C$, calculated by the conventional heat run test. However, the hot spot temperature measured using the optical fiber sensor was $129.4^{\circ}C$ between turns 2 and 3 on the upper side of the low-voltage winding. Therefore, the hot spot temperature of the low-voltage winding measured using the optical fiber sensor was $21.0^{\circ}C$ higher than that calculated by the conventional heat run test.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.134-136
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• 1995

A superconducting parallel bifilar winding shows the phenomenon which is known as 'fast quench'. We analyzed the temperature characteristics on the winding by computer simulation, and confirmed theses by experiment. The temperature of the quenched point rose gradually as the source voltage was increased. The temperature changed radically as first, but had a gentle slope after a few milliseconds. As the source voltage was large, the initial quenched length also increased. The points in this quenched length showed almost the same temperature. but the points where initial quench had not occurred showed radical temperature gradient. We could observe that the temperature of the whole wire increased simultaneously as the fast quench occurred on the superconducting parallel bifilar winding, because a number of quenched points in that wire appeared at the same time.

• Journal of Electrical Engineering and Technology
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• v.8 no.1
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• pp.144-149
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• 2013

This work deals with the optimal design of a coreless PMLSM (Permanent Magnet Linear Synchronous Motor) with consideration of rising winding temperature. The temperature distribution caused by copper loss in the coreless PMLSM was analyzed using a FEM (Finite Element Method). The thrust and current density where the winding temperature reaches the allowable temperature were calculated. The optimal model provides maximum thrust per unit weight.

• Journal of Electrical Engineering and Technology
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• v.8 no.2
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• pp.339-344
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• 2013

This research deals with design of the maximum thrust density with considering winding temperature rise of single-sided PMLSM. The temperature rise of winding which caused to machine characteristics such as copper loss, iron loss and efficiency was analyzed by FEM. The maximum allowable current density was calculated within the allowable temperature. The effects of loss and efficiency according to temperature characteristic were confirmed.

• Progress in Superconductivity and Cryogenics
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• v.12 no.4
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• pp.31-35
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• 2010

In superconducting magnet applications, winding methods of the superconducting magnet can be classified into a layer winding and a pancake winding. The superconducting magnet using high temperature superconductor (HTS) with rectangular shape is generally fabricated using the pancake winding method. On the other hand, low temperature superconducting (LTS) magnet may be wound by either a pancake winding or a layer winding. Compared with the layer winding, the pancake winding method has a merit of easy replacement of a damaged pancake module, but it also has a demerit of requirement of splicing between each double pancake modules. In this paper, we investigated characteristics of the layer and pancake winding methods using HTS. Six samples were wound out of BSCCO and Coated Conductors (CCs) by two winding methods and their characteristics were experimentally observed.

• Transactions on Electrical and Electronic Materials
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• v.17 no.5
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• pp.297-301
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• 2016

The effects of ambient temperature and diameter on the insulation lifetime of winding coils prepared with polyamideimide (PAI), flexural PAI (nanosilica 5 wt%) and anti-corona PAI (nanosilica 15 wt%) wires were investigated. The winding coils were made of enameled wire with enamel thickness of 30~50 μm. The thickness and width of the rectangular copper wires were 0.77~0.83 mm and 1.17~1.23 mm, respectively. The insulation breakdown lifetime decreased with increasing ambient temperature regardless of wire type and winding coil diameter under an inverter surge of 1.5 kV/20 kHz. The insulation breakdown lifetimes of φ5 mm winding coils at 150, 200, and 250℃ were 11.38, 5.19, and 4.22 min respectively, and those of φ10 mm winding coils at 150, 200, and 250℃ were 11.32, 5.79, and 4.57min respectively. The winding coil diameter had little effect on the insulation lifetime.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.4
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• pp.256-260
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• 2015

In this paper, achieved rise temperature distribution about degradation phenomenon of 24 MVA distribution cast resin transformer using CFD(Computational Fluid Dynamics). Usually, life of transformer is depended on temperature distribution of specification region than thermal special quality of transformer interior. Specially, life of transformer by decline of dielectric strength decreases rapidly in case rise by strangeness transformer interior hot spot temperature value permits. Because calculating high-voltage(HV) winding and low-voltage(LV) winding of cast resin transformer and Joule's loss of core for improvement these life, forecasted heat source, and HV winding and LV winding of cast transformer rise temperature distribution of core for supply of electric power and temperature distribution of highest point on the basis of the results. Also, calculated temperature rise limit of cast resin transformer and permission maximum temperature using analysis by electromagnetic heat source. Calculated and forecasted rise temperature distribution by heat source of thermal analysis with calculated result.

• Progress in Superconductivity and Cryogenics
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• v.14 no.1
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• pp.30-33
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• 2012

A double pancake winding method is widely used to make the superconducting magnet, using high temperature superconductor (HTS) tape. In the double pancake winding method, the joints with contact resistances between double pancake coils are inevitably needed. The electrical joule heating on the contacts causes refrigerant loss during operation. And a space outside the winding, for splices and mechanical support, is more than that for its layer-wound equivalent. In this paper, a double pancake winding method in order to reduce the number of the joints was proposed. Both of the double pancake coils using the conventional winding method and the proposed winding method have been fabricated and tested to make the solution technically feasible in the double pancake winding method. Especially, critical-current tests of the fabricated double pancake coils were conducted in order to show the same performance and confirm contact resistances between double pancake coils.