• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11b
• /
• pp.605-608
• /
• 2001

With the intention of investigating the breakdown properties of oil-immersed transformer oils in temperature range of $20\sim100[^{\circ}C]$, we are made researches AC breakdown in the gap of $500\sim2500[{\mu}m]$. The classification for the physical properties of oil for oil-immersed transformer by FTIR and H-NMR experiments was confirmed to type of mineral oils. As the dependance of breakdown properties due to electrode gap length variation, breakdown voltage was found increasing according to the increase of gap, while dielectric strength was decreasing. As a result the characteristics for AC breakdown, It goes to prove that the breakdown voltage was increased to $90[^{\circ}C]$ but decreased over $90[^{\circ}C]$ in the temperature range. Also, breakdown voltage was found increasing in the increase of gap and the rising of temperature according to Weibull distribution.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07a
• /
• pp.78-81
• /
• 2004

In this paper, the effect of adhesion properties of semiconductive-insulating interface layer of silicone rubber on electrical properties was investigated. Surface structure and adhesion of semiconductive silicon rubber by surface asperity was obtained from SEM and T-peel test. In addition, ac breakdown test was carried out for elucidating the change of electrical property by roughness treatment. From the results, Adhesive strength of semiconductive-insulation interface was increased with surface asperity. Dielectric breakdown strength by surface asperity decreased than initial Specimen, but increased from Sand Paper #1200. According to the adhesional strength data unevenness and void formed on the silicone rubber interface expand the surface area and result in improvement of adhesion. Before treatment Sand Paper #1200, dielectric breakdown strength was decreased by unevenness and void which are causing to have electric field mitigation small. After the treatment, the effect of adhesion increased dielectric breakdown strength. It is found that ac dielectric breakdown strength was increased with improving the adhesion between the semiconductive and insulating interface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1996.11a
• /
• pp.425-428
• /
• 1996

Treeing deterioration which is one of the main cause of breakdown in insulating materials is affected by temperature, applied voltage and frequency. In this study, GN was introduced to improve impact strength of DGEBA/MDA system and the temperature dependence of AC treeing deterioration in this system was investigated. Dielectric breakdown strength decreased with the increment of temperature. As temperature increased, the growth rate of tree Increased.

• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.7
• /
• pp.502-507
• /
• 1998

The purpose of this study is to investigate the breakdown properties in joint interface of power cables with heat treatment. The specimens have the structure of XLPE/EPDM interface like the joint of distribution power cable. The breakdown characteristics of the SLPE/EPDM joint were studied with crosslinking by=products. AC breakdown voltages were measured with heat treatment time and interfacial materials and crosslinking by-products as testing factors. This study has shown that crosslinking by-product gases play an important role at the insulation properties of cable joints by heating. The dielectric strength shows the lowest values at 4 hours heat treatment. The AC breakdown strength in the untreated sample was increased with heat treatment time.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.67 no.12
• /
• pp.1633-1640
• /
• 2018

Epoxy resin is a polar thermosetting polymer that is widely employed in different branches of industry and everyday life, due to their stable physical and chemical properties. Of all the polymer materials currently being used in the electrical insulation industry, epoxy resin is the most widely used kind, chosen as the base polymer material in the present study. Composites were prepared according to the mixing ratio (MS: MA, 1: 9, 3: 7, 5: 5, 7: 3, 9: 1)of mixture for Heterogeneous Minerals(Micro Silica:MS, Micro Alumina:MA) (MS+MA). We have investigated for AC electrical insulation breakdown characteristics and the dielectric properties (permittivity, dielectric loss, and conductivity) with frequency changes. The electrical AC insulation breakdown performance was improved with the increase of the mixing ratio of MS according to heterogeneous mineral material mixture(MS+MA). As Dielectric properties, the dielectric constant and dielectric loss increased with decreasing frequency and decreased with increasing MS content ratio of heterogeneous mineral mixture. Tensile strength and flexural strength according to the mixing ratio (MS + MA) of epoxy / heterogeneous mineral mixture were studied by mechanical properties. The performance of mechanical tensile and flexural strength was significantly improved as the fill contents ratio of MS increased.

• Transactions on Electrical and Electronic Materials
• /
• v.14 no.4
• /
• pp.199-202
• /
• 2013

In order to study the effect of reactive diluents on the electrical insulation breakdown strength and mechanical properties of, a polyglycol and an aliphatic epoxy were individually introduced to an epoxy system. Reactive diluents were used in order to decrease the viscosity of the epoxy system; polyglycol acted as a flexibilizer and 1,4-butanediol diglycidyl ether (BDGE) acted as an aliphatic epoxy, which then acted as a chain extender after curing reaction. The ac electrical breakdown strength was estimated in sphere-to-sphere electrodes and the electrical breakdown strength was estimated by Weibull statistical analysis. The scale parameters of the electrical breakdown strengths for the epoxy resin, epoxy-polyglycol, and epoxy-BDGE were 45.0, 46.2, and 45.1 kV/mm, respectively. The flexural and tensile strengths for epoxy-BDGE were lower than those of the epoxy resin and those for epoxy-polyglycol were lower than those of the epoxy resin.

• International Journal of Safety
• /
• v.8 no.1
• /
• pp.14-17
• /
• 2009

The $Co^{60}$ $\gamma$-ray irradiation effects on the electrical and thermal characteristics of low density polyethylene crosslinked by Dicumyl peroxide (DCP) were investigated. We experimented on electrical properties as following; electrical tree inception and growing type for applying AC step voltage, AC breakdown strength, volume resistivity with increasing dosage. Also, chemical analyses were performed TGA, gel fraction. These electrical properties changed depending upon its crosslinking degree and byproducts from crosslinking reactions. Crosslinking reactions were considered causing by $\gamma$-ray irradiation and DCP had contained in low density polyethylene.

• Proceedings of the KIEE Conference
• /
• 1996.11a
• /
• pp.273-275
• /
• 1996

In order to investigate the electrical properties of naphthanic transformer oils for insulating and cooling, the characteristics for breakdown in temperature range of $20{\sim}100[^{\circ}C]$, that of AC breakdown in 1.0[mm] of gap length were made researches. As a result the characteristics for AC breakdown, it is confirm that the dielectric strength was increased to 6[ppm], 9[ppm] but decreased to 3[ppm].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.11a
• /
• pp.150-150
• /
• 2009

In this paper, various kinds of epoxy based nanocomposites were made and AC breakdown properties of nano-$TiO_2$ and micro-silica filler mixture of epoxy based composites were studied by sphere to sphere electrode. Moreover, nano- and micro-filler combinations were adopted as an approach toward practical application of nanocomposite insulating materials. AC breakdown test was performed at room temperature $(25^{\circ}C)$, $80^{\circ}C$ and $100^{\circ}C$. The result shows breakdown strength about non-filled, nano-scale $TiO_2$, micro-scale silica and nano-$TiO_2$, micro-silica filled epoxy composites.