• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.11a
• /
• pp.332-333
• /
• 2006

The properties of a cable Insulate capacity between surfaces with the variation of the interfacial breakdown, the addition of silicon oil, the variation of pressure and interfacial roughness were investigated. The Insulate trouble of a power cable is out of the interfacial parts, which breakdown the insulate breakdown capacity in a power cable. In this study, the analysis of electric field and the phenomenon of interfacial breakdown were reported by varying the surfaces condition of silicon rubber, XLPE used for connection materials of a power cable.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2011.11a
• /
• pp.65-67
• /
• 2011

It is necessary to the development of the best maintenance system for applying the long-term maintenance plan using the cost breakdown structure in the educational facilities. This study developed the cost breakdown structure for the best maintenance system using the delphi method. For the convenience of maintenance, the maintenance cost breakdown structures are separated into building exterior wall, building inside wall, electric installation, heating installation and outdoor facilities. And these results atomized in each parts. And this study constructed the cost breakdown structure to maintenance's practicality and effectiveness through the expert analysis.

• Electrical & Electronic Materials
• /
• v.10 no.3
• /
• pp.247-254
• /
• 1997

Internal voids in insulators give rise to partial discharge, which causes a local breakdown and even entire insulation breakdown. Recently, the necessity of establishing the way to diagnose the aging of insulation materials and to predict of insulation breakdown become important. The purpose of our work are to investigate the treeing phenomena with an artificial needle shaped void by the charge of discharge and acoustic emission pulse in each phase angle area at the same time. We analyzed the .PHI.-QA-t pattern and .PHI.-AEA-t pattern using statistic operators such as pulse magnitude, pulse number, skewness, kurtosis. Therefore, the relation between the charge of discharge and acoustic emission pulse will be helpful to predict the breakdown just before the breakdown occur.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.1200-1203
• /
• 2003

The dielectric breakdown of epoxy composites used for transformers was experimented and then its data were applied to Weibull distribution probability. First of all, speaking of dielectric breakdown properties, the more hardener increased, the stronger breakdown strength became at low temperature because of cross-linked density by the virtue of ester radical. The breakdown strength of specimens with filler was lower than it of non-filler specimens because it is believed that the adding filler forms interface and charge is accumulated in it, therefore the molecular motility is raised and the electric field is concentrated. In the case of filled specimens with treating silane, the breakdown strength become much higher. Finally, according to Weibull distribution analysis, reducing breakdown probability of equipment insulation lower than 0.1% level requires the allowable field allowable field intensity values to be kept under 21.5 MV/cm.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2008.05a
• /
• pp.301-304
• /
• 2008

This paper presents the experimental results on breakdown characteristics in $N_2$ gas under non-uniform electric fields caused by both the positive and negative lightning impulse voltages. $N_2$ gas have an advantage of eco-friendly and cost reduction, and safety aspects. In order to analyze the impulse pre-breakdown processes in $N_2$ gas, we carried out measurements and observations of the impulse breakdown voltages, pre-breakdown current and luminous signals. They were measured by a voltage divider, a shunt and a photo-multiplier tube, respectively. Additionally, the characteristics of discharge channels were observed by high speed cameras. The breakdown voltages in the positive polarity was lower than those in the negative polarity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11b
• /
• pp.597-600
• /
• 2001

In order to investigate the electrical properties of X-ray tube oils for insulating and cooling, the breakdown characteristics in temperature range of $20\sim100[^{\circ}C]$, that of AC breakdown in 0.5~2.5[mm] of gap length, we are made researches. The classification for the physical properties of oil for X-ray tube by FTIR and H-NMR experiments was confirmed to type of mineral oils. As for the dependance of breakdown characteristics due to electrode gap length, breakdown voltage was found nearly uniform by impurity effect according to the increase of gap. As a result the characteristics for AC breakdown, the dielectric strength was increased to $90[^{\circ}C]$ but decreased over $90[^{\circ}C]$ in the temperature range.

• Proceedings of the KIEE Conference
• /
• 2002.07c
• /
• pp.1827-1829
• /
• 2002

This paper describes AC test for long delivered drum length of cable using pre-breakdown partial discharge detection(PPD) method, which can be applied to observe the causes of electrical breakdown of EHV XLPE insulation. This method is to de-energize applied voltage to cable rapidly using pre-breakdown partial discharge, and is able to prevent complete breakdown. By this effect, defects such as voids, metal particles and protrusion in cable can be observed clearly. AC resonant test set was used for PPD method. Localization of partial discharge was performed by time difference detection of the traveling wave. Accuracy of localization was 1% to the length of test cable. Through several experiments with XLPE cable, successful results of PPD method were obtained.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.8
• /
• pp.647-651
• /
• 2001

The dielectric breakdown of epoxy composites used for transformers was experimented and then its data were applied to Weibull distribution probability. First of all, speaking of dielectric breakdown properties, the more hardener increased, the stronger breakdown strength became at low temperature because of cross-linked density by the virtue of ester radical. The breakdown strength of specimens with filler was lower than it of non-filler specimens because it is believed that the adding filler forms interface and charge is accumulated in it, therefore the molecular motility is raised and the electric filed is concentrated. In the case of filled specimens with treating silane, the breakdown strength become much higher. Finally, from the analysis of weibull distribution, it was confirmed that to low allowed breakdown probability under 0,.1%, the applied field value needed to be under 21.5MV/cm.

• Proceedings of the KIEE Conference
• /
• 1997.07d
• /
• pp.1478-1480
• /
• 1997

We investigated the breakdown characteristic of mineral oil according to applied voltage and tip radius. In this experiment, electrode system was point-plane geometry. The tip radius of needle was 5, 10, 20 and $25{\mu}m$, respectively. Applied voltage was AC and DC. We measured breakdown voltage for each tip radius with increasing electrode gap, 2mm to 10mm. Under nonuniform electric field, breakdown strength was higher when needle was negative than when needle was positive. Because it is polarity effects due to space charge. And the more sharp tip radius, whether we applied AC or DC, the higher breakdown strength. As tip radius increase, breakdown strength decreases exponentially.

• Proceedings of the KIEE Conference
• /
• 1997.07d
• /
• pp.1414-1416
• /
• 1997

The electrical breakdown characteristics of the synthetic fluids No.2 of KS class VII used for insulating and cooling the materials for the ignition coil are studied. Also, Benzotriazole(BTA) as the streaming electrification suppressant additive is added to the oil, and the change of electrical properties due to different BTA concentration is investigated. To investigate the electrical characteristics, the breakdown strength of each specimen by an experiment for AC breakdown are analyzed. The breakdown strength of specimen by adding BTA is higher than virgin specimen in low e region, but lower than that in high region because of melting BTA. It is considered that the effective content of BTA as charge suppressant additive is about 10[ppm] from the results of AC breakdown.