• 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.

• 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 Ocean Engineering and Technology
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• v.10 no.3
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• pp.14-23
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• 1996

The corrosion fatigue test were carried out to evaluate the fatigue characteristics of accelerated cooled (ACC) TMCP high tensile strength steels and weld joint with high heat input by one side one run submerged are welding. In this paper, the fatigue crack growth behaviors were investigated with the center crack tension specimen of base metal and heat affected zone in substitute sea water and air, respectively Main results obtained are sunnarized as follows: 1. The fatigue crack growth rates in sea water faster than those in air environment for the different heat input values, crack growth rate of base metal is very fast and effect of heat input is not remarkable. 2. In HAZ (82kJ/cm, 116kJ/cm), the crack branching phenomena were observed in both air and sea water environment, 3. In SEM observation, the corrosion effect on base metal was larger than that on HAZ in corrosion environment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.9
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• pp.56-61
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• 2011

The temperature of power transformers is very important factor for power system operation in substation because load capacity and limited lifetime of power transformers are determined by winding temperature. Also, The temperature of power transformers varies with the structure, capacity, operation condition and manufacturers. Thus, it is necessary for temperature distribution to be exactly investigated because of efficient load management and prediction of limited lifetime. Nevertheless, there was no case of analysis as well as measurement of the temperature of power transformers. In this paper, we manufactured the 154kV standard power transformer for the test. And we measured the temperature by the heat run test and analyzed the temperature distribution of transformer.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1997.11a
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• pp.193-200
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• 1997

Flame spread and heat release properties and incident heat flux of interior materials subject to an igniter heat flux in a compartment are investigated and compared by using computer model. A comer fire ignition source is maintained for 10 minutes at 100 kw and subsequently increased to 300kw. In executing the model, base-line material properties are selected and one is changed for each run. Also 4 different igniter heat flux conditions and examined. Results are compared for the 12 different materials tested by the ISO Room Comer Test (9705). The time for total energy release rate to reach 1MW is examined. The parameters considered include flame heat flux and thermal inertia, lateral flame spread parameter, heat of combustion and effective heat of gasfication. The model can show the importance of each property in causing fire growth on interior Hnish materials in a compartment. The effect of ignitor heat flux and material property effects were demonstrated by using dimensionless parameters a, b and Tb. Results show that for b greater than about zero, flashover time in the ISO Room-Corner test is principally proportional to ignition time and nothing more.

• Progress in Superconductivity and Cryogenics
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• v.6 no.1
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• pp.38-42
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• 2004

The cryogenic system for 6.6 kV/200 A inductive superconducting fault current limiter (SFCL) was developed at Yonsei university in 2003. The sub-cooled nitrogen cryogenic system could be applied to not only SFCL but also many other applied high-Tc superconducting (HTS) devices like superconducting motor, superconducting generator and superconducting magnetic energy storage (SMES). Generally, the cooling capacity of GM-cryocooler depends on the load temperature. Therefore it is necessary to perform the cooling capacity test at no load condition to calculate the exact cooling power and heat load of cryogenic system. In this research, the cooling capacity test of GM-cryocooler was executed and the heat load of developed cryogenic system was calculated. The long run operation test results of sub-cooled nitrogen cryogenic system were successful in pressure and temperature condition. Moreover, the design and fabrication method of cryogenic system were introduced and the test results were described.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.1
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• pp.45-53
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• 2017

A high resolution model is proposed for calculating the temperature field of a large city, based upon a Lagrangian particle model. Utilizing the analogy between the heat and mass transport phenomena in turbulent flows, a Lagrangian particle model, originally developed for air pollutant dispersion problems, is adapted for simulating heat transport. In the model conceptual heat particles are released into the atmosphere from the heat sources and move along with the turbulent winds in accordance with the Markov process. The potential temperature assumed to be conserved along with heat particles serves as a tag, so the temperature fields can be deduced from the distribution of particles. The wind fields are constructed from a diagnostic meteorology model incorporating a morphological model designed for building flows. Test run shows the robustness of the modeling system.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.3
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• pp.277-284
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• 2013

In this paper, the ventilating and heating system of T-103 trainer aircraft were investigated and redesigned to improve its poor performance. The ventilation system of the trainer was designed to increase the mass flow rate of fresh air by using air intake valves. The flow-in air through the air intake valve is supplied to the cabin by the ram effect of aircraft and the propeller. And the additional heating system was installed to improve the temperature of the cabin inside. The wasted heat from the exhaust gas of the engines was used as heat source of the additional heating system by installing an heat exchanger around the exhaust nozzle. The additional fresh air and the heated air enter the cabin via two ducts mounted under the instrument panel and behind the pedal in the cabin. The additional ventilating and heating system can be controlled by the first pilot and the secondary pilot individually using the control knob equipped separately. After mounting the additional ventilating and heating system, evaluations such as inspection of parts and component, ground run-up test, in-flight test, user test, etc. were conducted. The result of the tests was sufficient to meet the requirements of the manuals, and the pilots were satisfied with the additionally mounted systems.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.6
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• pp.817-823
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• 2011

This paper proposes a cooling stop temperature control(CST) and a phase transformation control(PTR) which aim at obtaining the uniform temperature and quality along the longitudinal direction of the high strength steel on the run-out table(ROT) process. The problems of the temperature control are analyzed for the conventional steel and the new control concepts are derived from a time-temperature transformation(TTT) diagram. The proposed control technologies are verified from the simulation results under the temperature prediction model by the heat transfer governing equation, and the temperature estimation simulator. It is shown through the field test of the hot strip mills that the phase transformation ratio of the high strength steel is considerably improved by the proposed temperature controls.

• Nuclear Engineering and Technology
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• v.50 no.3
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• pp.356-367
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• 2018

A series of tests dedicated to station blackout (SBO) accident scenarios have been recently performed at the $Prim{\ddot{a}}rkreislauf-Versuchsanlage$ (primary coolant loop test facility; PKL) facility in the framework of the OECD/NEA PKL-3 project. These investigations address current safety issues related to beyond design basis accident transients with significant core heat up. This work presents a detailed analysis using the best estimate thermal-hydraulic code TRACE (v5.0 Patch4) of different SBO scenarios conducted at the PKL facility; failures of high- and low-pressure safety injection systems together with steam generator (SG) feedwater supply are considered, thus calling for adequate accident management actions and timely implementation of alternative emergency cooling procedures to prevent core meltdown. The presented analysis evaluates the capability of the applied TRACE model of the PKL facility to correctly capture the sequences of events in the different SBO scenarios, namely the SBO tests H2.1, H2.2 run 1 and H2.2 run 2, including symmetric or asymmetric secondary side depressurization, primary side depressurization, accumulator (ACC) injection in the cold legs and secondary side feeding with mobile pump and/or primary side emergency core coolant injection from the fuel pool cooling pump. This study is focused specifically on the prediction of the core exit temperature, which drives the execution of the most relevant accident management actions. This work presents, in particular, the key improvements made to the TRACE model that helped to improve the code predictions, including the modeling of dynamical heat losses, the nodalization of SGs' heat exchanger tubes and the ACCs. Another relevant aspect of this work is to evaluate how well the model simulations of the three different scenarios qualitatively and quantitatively capture the trends and results exhibited by the actual experiments. For instance, how the number of SGs considered for secondary side depressurization affects the heat transfer from primary side; how the discharge capacity of the pressurizer relief valve affects the dynamics of the transient; how ACC initial pressure and nitrogen release affect the grace time between ACC injection and subsequent core heat up; and how well the alternative feeding modes of the secondary and/or primary side with mobile injection pumps affect core quenching and ensure stable long-term core cooling under controlled boiling conditions.