• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.11a
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• pp.110-113
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• 1992

This paper presents the results on experiments of relative dielectric constant dielectric loss, conductivity change and breakdown voltage of the L.D.P.E. mixed with Dodecyl Alcohol. The frequency range is 0.1 - 20 MHz and temperature, 20 - 80 $^{\circ}C$. Dielectric properties were similar to those of nonpolar polymers. Until $60^{\circ}C$ the conductivity value of compound was decreased with temperature increasment. And, its breakdown voltage was measured higher, about 3-4KV, than that of the pure L.D.P.E.. Also the amount of remnants of DA in the compounds were considered.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.253-255
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• 2008

This paper gives a basic data of the surface discharge characteristics for epoxy resin in Dry-Air. Used electrodes are needle to plane, sphere to plane and KS M3015 electrodes. With the changing electrodes in same condition, we can obtain different creeping lengthes, breakdown voltages and dielectric strengths, respectively. Dielectric strengths of Needle to plane electrodes are more higher than the others. Breakdown voltage and dielectric strength increase as the thickness of epoxy resin and creeping strength increase.

• 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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• 2000.11a
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• pp.9-12
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• 2000

Insulators for high-voltage and large-power should be endured mechanically the weight of mold bushing itself and the force of pushed from contact with circuit breaker and conductor. But dielectric breakdown could be occurred result from the external circumstances and internal factors such as chemical reaction, partial discharge, change of temperature and the relation of temperature-time in process of casting. Therefore, to get rid of external and internal factors of dielectric breakdown. Furthermore, to prevent the internal cracks, void, cavity which resulted from the contraction originated on the interface between copper and epoxy resin, formed semi-conductive layer with partially carbon painted on copper bar. The PD properties and the insulation qualities of epoxy molded insulators were improved by roles of cushions for the direction of diameter and natural sliding effects as like separated from conductor for the direction of length.

• Journal of the Korean Ceramic Society
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• v.29 no.7
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• pp.572-576
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• 1992

Dielectric constant of ferroelectric ceramics with poling is important in relation to the mechanism of dielectric breakdown. From the research about the dielectric constant variation with poling in tetragonal and rhombohedral phase PZT ceramics, it is known that the dielectric constant after poling is determined by competing effects between increasing effects (compressive stress induced by electrostriction of piezoelectric effects) and decreasing increase in large grain size with poling is smaller than in small grain size.

• Electrical & Electronic Materials
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• v.8 no.4
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• pp.413-417
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• 1995

In order to elucidate the electrical and mechanical properties of insulating paper, it is desirable to study the performances of tensile strength, dielectric constant, dielectric strength. In this work, we constructed the characteristics depending on change of fabrication condition, and these specimens were manufactured by hot press method. As a result, tensile strength was about 75MPa and breakdown was above 5 kV/mm at the minimum value.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1596-1598
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• 1999

In order to determine what influences the interfacial breakdown between two internal dielectric surfaces. We studied the interfacial breakdown phenomena at several interfacial conditions. With the increase of interfacial pressure, at first breakdown strength in interfaces was increased, and then saturated. Breakdown strength in interface pasted with silicone oil was higher than that with silicone grease. As a function of heat treatment time in a vacuum oven interfacial breakdown strength was increased much in XLPE/EPDM laminates pasted with silicone grease but increased a little in that with silicone oil. As an increase of curing agent in silicone oil and grease, breakdown strength in interfaces was increased and then saturated.

• 전기의세계
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• v.30 no.4
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• pp.231-236
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• 1981

It has been known that D.C. breakdown Voltage is lower than A.C. breakdown Voltage in insulatingoil, but there are still many unvivid points at electric conduction in breakdown or under of high electric field. This study measured the electric current-electric field characteristics (I-E characteristics) and the breakdown Voltage under of D.C. electric field of insulating oil using the system of electrodes that are near the Uniform electric field with a result. I can study, electric conduction in area of high electric field depends upon the Schottky effect. The liquidity of breakdown electric field takes place by the local concentration of electric field. The longer gap is and the more electric current is the more breakdown Voltage decreased. There are not almost the change of electric current-electric field characteristics by materials of electrode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.260-264
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• 1996

In this study, the dieiectric breakdown of epoxy composites used for transformers was experimented and then its data were simulated by Weibull distribution probability . As a result. first of all, speaking of dielectric breakdown properties, the more hardener increased the stronger breakdown strength at low temperature, and the breakdown strength of specimens because it is believed that the adding filler farms interface and charge is accumulated in it, therefore the molecular motility is raised, the electric field is concentrated, and the acceleration of electron and the growth of electron avalanche are early accomplished. In the case of filled specimens with treating silane, the breakdown strength become much higher since the suggests that silane coupling agent improves interfacial combination and relays electric field concentration. Finally, from the analysis 7f weibull distribution. it was confirmed that as the allowed breakdown probability was given by 0.11[%].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.437-440
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• 2000

In this study, the interfacial dielectric breakdown phenomenon of interface between Epoxy and Rubber was discussed, which affects the stability of insulation system of power delivery devices. The breakdown strength of specimens are observed by applying high AC voltage at the room temperature. The breakdown times under the constant voltage below the breakdown voltage were gained. As constant voltage is applied, the breakdown time is proportion to the breakdown strength. The life exponent n is gained by inverse power law and the long time breakdown life time can be evaluated.