• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.193-196
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• 2001

XLPE is occasionally happened to deteriorate cable insulation characteristics. It is happened to do a breakdown state by the degradation of electrical characteristic and electrical breakdown strength. I prepared TR-XLPE (Tree-Retardant XLPE) as adding various additives to prevent its states. Various additives are treeing retardants, anti-oxidants. Treeing retardants three kinds of aromatic compounds as adding each additive. Anti-oxidants use quinone compound and cresol compound as adding each additive. In order to observe each electrical characteristics, I measured breakdown strength, relative dielectric constant$({\varepsilon}_r)$, dielectric loss tangent$(tan{\delta})$. TR-XLPE specimens as adding treeing retardants and anti-oxidants enhance breakdown strength, ${\varepsilon}_r$, $tan{\delta}$ than pure XLPE.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1688-1691
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• 1997

In this work, we have developed the off-line diagnostic system for power cable insulation using DC voltage decay method to diagnose the insulation degradation of underground power cables. Measurement errors of diagnostic system are less than 1% for $1T{\Omega}$ internal resistor. We have also developed measurement and diagnostic programs for win95 which is suitable for the database construction and the management of data. We could conclude that it is possible to apply this system to the multi-grounded underground cable systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.256-257
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• 2008

Recently, with the increase of demand of electricity, electric cable or electric transfer machine are rapidly developed and meet the demand with the extra high voltage and massive capacity, the dangers of electrical accident of insulator are increasing by the electric stress, insulation degradation and insulation breakdown in insulator. In this paper, it is investigated that the temperature dependance of dielectric strength in nano-composites. We obtained that breakdown voltage of 0.4 [wt%] specimens is higher than the other $SiO_2$ content.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.169-172
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• 1999

Recently, the wavelet transform has been a new and powerful tool for signal processing. It is more suitable specially for the feature extraction and detection of non-stationary signals than traditional methods such as, the Fourier Transform(FT), the Fast Fourier Transform(FFT) and the Least Square Method etc. because of the characteristic of the multi-scale analysis and time-frequency domain localization. The wavelet transform has been developed for the analysis of PD pulse signal to raise in the progress of insulation degradation. In this paper, the wavelet transform was applied to one foundational method for feature extraction. For the obtain experimental data, a computer-aided partial discharge measurement system with a single acoustic sensor was used. If we are applying to the neural network method the accumulated data through the extracted feature, it is expected that we can detect the PD pulse signal in the insulation materials on the on-line.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.8
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• pp.82-87
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• 2011

Induction motor is most widely used as the driving power in the industrial site. Induction motor current is composed of two parts, magnetizing current and load current. Load current uses energy what is doing the work. Load current varies with load variance but magnetizing current is constant, regardless of load variation. Magnetizing current needs for establishing the rotating magnetic field of induction motor and lags behind the voltage. Generally capacitor is used for power-factor compensation of inductive load. Self-excitation occurs when the capacitive reactive current from the capacitor is greater than the magnetizing current of the induction motor. When this occurs, excessive voltages can result on the terminals of the motor. This excessive voltage can cause insulation degradation and ultimately result in motor insulation failure. In this paper, we analyzed that how the magnetizing current and condenser current is operating at the allowable limit by the load variation. Condenser current is below allowable limit of magnetizing current but magnetizing current is above allowable limit at the lower load operation condition.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1476-1477
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• 2006

Solid insulation exposed to voltage is degraded and by electrical tree process. And the degradation of the insulation is accelerated by voltage application. For this experimental, specimen of electrical tree model is made by XLPE(cross-linked polyethylene). And the size of the specimen is 7*5*7 $mm^3$. Distance of needle and plane is 2mm. Voltage applied for acceleration test are 12kV. And distribution characteristic of degraded stage is studied too. As a PD detecting and data process, discharge data acquire from PD detecting system(Biddle instrument). Their results of PD distribution show good present and are good discriminating skill.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.965-966
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• 2007

For practical electrical insulation design of high temperature superconducting (HTS) power apparatuses, knowledge of the dielectric behavior of insulators in cryogenic liquid such as liquid nitrogen ($LN_2$) is essential. So in this paper, we discussed experimental investigations of breakdown and V-t characteristics of several insulators such as Kapton and glass fiber reinforced plastic (GFRP) that are candidates of insulator for HTS apparatus in cryogenic liquid. And we investigated the degradation of these insulation samples after breakdown with the microscope and SEM photograph. Moreover, survival and hazard analysis was performed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.631-635
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• 2000

Recently, the epoxy molded type PT for indoor and applied 25.8kV was often distroyed by degradation of insulation that effected many electric stress and defect of manufactured goods. therefore In this work, We can present a method of solution in the process of produce the PT through analysis of experiments. In order to reduce the PD (Partial Discharge) which was occurred at the insulation material of epoxy resin, we has many tried to remove faults In the process of the products,

• Progress in Superconductivity and Cryogenics
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• v.17 no.1
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• pp.48-52
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• 2015

The electrical insulation design for a superconducting coil system is important for developing high voltage superconducting apparatuses. Also, the degraded characteristics of superconducting tapes due to an electrical breakdown should be considered for superconducting coils design. In this study, the degradation characteristics of 2G high temperature superconducting (HTS) tapes were studied with respect to electrical breakdown tests. The degradation tests of 2G HTS tapes were performed with various stabilizer materials. The degradation characteristics of 2G HTS tapes such as critical current(Ic) and index number were observed by performing electrical breakdown tests. It was found that the characteristics such as Ic and index number can be degraded by an electrical breakdown. Moreover, it was concluded that the degradation characteristics of 2G HTS tapes were affected by a stabilizer material and applied breakdown voltage. The cross sectional view of 2G HTS tapes was observed by using a scanning electron microscope (SEM). As results, it is found that the degradation characteristics of 2G HTS tapes are concerned with hardness and electrical resistivity of stabilizer layers.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.2
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• pp.102-105
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• 2009

The accelerated life time test of the MLCCs with different $BaTiO_3$ particle sizes were conducted at $150^{\circ}C$, 75 V condition and the effect of $BaTiO_3$ particle size on the breakdown voltage and degradation characteristics of MLCCs was investigated. The MLCCs were prepared by using the $BaTiO_3$ particles having the size of $0.525{\mu}m$, $0.555{\mu}m$, $0.580{\mu}m$ and Ni-electrode, respectively. The MLCCs which have the particle size of $0.525{\mu}m$, $0.555{\mu}m$, and $0.580{\mu}m$, respectively were confirmed to meet the standard requirements of X5R(change capacitance within ${\pm}15%$ at $-55{\sim}85^{\circ}C$) by TCC(Temperature Coefficient of Capacitance). The effect of the $BaTiO_3$ particle size on the insulation resistance behavior of MLCCs was confirmed by BDV(Breakdown Voltage) measurements and the cause and degree of degradation of MLCCs were characterized by XPS analysis after the accelerated life test. The MLCCs with $0.525{\mu}m-BaTiO_3$ showed better insulation resistance and BDV characteristics compare to other MLCCs and XPS analysis revealed that the MLCCs degradation is caused by the NiO peak and $BaTiO_3$ peak decrease.