• KIEE International Transactions on Electrophysics and Applications
• /
• 제2C권6호
• /
• pp.321-326
• /
• 2002

This paper describes the mechanical and electrical characteristics of insulating paper impregnated with diluted varnish(W-128), according to Korean Standards. The varnish was diluted with a solvent of 6 different wt%. Kraft paper and Nomex paper were impregnated with the diluted varnish in a vacuum condition, and then completely dried. As the mechanical characteristics, the thickness of the completely dried varnish, the drying time and the tensile strength of the specimens were measured, and as the electrical characteristics, the permittivity, the tan $\delta$ and the specific resistance were evaluated as well.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1994년도 추계학술대회 논문집
• /
• pp.147-151
• /
• 1994

In order to investigate the dielectric characteristic insulating oil is chosen insulating oil for electric cable, and experiment is performed in the temperature range of 30∼120[$^{\circ}C$] and frequency range of 30∼1${\times}$10$\^$6/[㎐]. As a result, the observed linear decrease in tan $\delta$ value at the low frequency range is due to the influence of frequency, whereas the increase in tan $\delta$ value at high frequency range is contributed by the electrode's resistance and dielectric loss. The dipole moment and activation energy of specimen are obtained 1.22(debye) and 12.75∼18.66[㎉/㏖e] of high temperature region, 15.68 ∼ 20.6[㎉/㏖e] of low temperature region respectively.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 하계학술대회 논문집 C
• /
• pp.1452-1454
• /
• 2002

Large turbine generator(rated 22kV) has failed in the stator winding area during normal operation. The capacitance and tan${\delta}$ were measured by Schering bridge in the zone 1, 2 and zone 3-6 stator windings. The capacitance and tan${\delta}$ in the zone 1, 2 of stator winding were higher than those of zone 3-6 in the stator winding. Experiments on microstructure property were conducted in the zone 1, 2 and zone 3-6 insulations, which were drawn out from stator windings of the large turbine generator. Microstructure analysis was characterized using scanning electron microscope(SEM). SEM results indicated that several isolated delaminations occurred at the interface of mica/epoxy insulations. Both thermal and mechanical aging cause the delamination.

• 한국광학회지
• /
• 제3권2호
• /
• pp.92-100
• /
• 1992

회전검광자형의 분광타원해석기를 제작하였다. 각 부품의 미소결함에 의한 오차를 고려하여 이들이 타원해석상수들에 미치는 영향을 최소로 하는 배치를 결정하였다. Straight through operation의 성능평가 결과 300nm~850nm의 파장대역에 걸쳐 tan$\psi$와 cos$\Delta$의 편차는 0.2%내외로 만족할 만한 것으로 판단되었다. SE를 사용하여 불화박막의 굴절율및 void분포상태를 측정하였고 응용성에 관하여 논의하였다.

• 공업화학
• /
• 제5권4호
• /
• pp.722-730
• /
• 1994

전기절연체로 사용되는 가교폴리에틸렌(XLPE)의 내후성에 미치는 산화방지제(Antioxidant)와 카본블랙의 효과를 살펴 보았다. 산화방지제와 카본블랙을 조합하여 16가지의 시료를 제작하고 xenon-arc lamp type의 Weather-Ometer로 500, 1000, 1500, 2000 시간 촉진열화시켰을 때 촉진열화 각 시간대별로 열화거동을 관찰하였다. 인장강도, 신장율, 절연파괴전압, tan ${\delta}$로 XLPE의 내후성을 평가한 결과, 산화방지제보다는 카본블랙이 더 효과적이었고 두 첨가제를 조합해서 사용할 때 내후성이 우수한 synergistic effect를 나타냈다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
• /
• pp.304-306
• /
• 1987

The dielectric loss ($tan{\delta}$) and the Capacitance (C) of the PPMKA(plasma-polymerized methyl metacrylate) films were measured in the frequency range of 1KHz - 5MHz at $25^{\circ}C$. The effects of the oxidation and the heating and the plasma treatment for $tan{\delta}$ and C of PMMA were investigated. Dielectric loss of PPMMA films was inceased with the oxidized products like CO and OH. As condidates for their origin the existence of low molecula moieties and free radicals in the PPMMA, and the crosslinking made by the heating and plasma treatment have been considered.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1994년도 하계학술대회 논문집 C
• /
• pp.1265-1267
• /
• 1994

EPDM has excellent electric characteristics and so that it has been rapidly finding use is high voltage applications in recent years. At present EPDM is widely used for insulator of cable and accessories, and further the commercial use of Premolded housing for elbow surge arrester is started. In this paper, we have measured the temperature, pressure and voltages dependence of $tan{\delta}$ in EPDM. As a results, dielectric characteristics($tan{\delta}$) increases slightly with increasing the temperature. However, it is almost independent of the pressure and voltages.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
• /
• pp.447-449
• /
• 1999

In this paper, we were evaluated dielectric properties and temperature dependency in aging semifilm and PET film. According to humidity, dielectric properties of PET film increased, but tan $\delta$ presented a constant transition. According as temperature increased, tan $\delta$ increased from 1.9$\times$10$^{-3}$ to 2.76$\times$10$^{-3}$ and capacitance increased from 244.1(PF) to 297.5(PF).

• 한국전기전자재료학회논문지
• /
• 제13권10호
• /
• pp.847-858
• /
• 2000

The aging characteristics of 2 kinds of 3 years field-aged distribution polymer insulators which were dismounted from 5 regions have been investigated by electrical test and material characterization. Although the tan $\delta$of specimens prepared from weathershed was increased with surface aging, the tan $\delta$and leakage current of real products had no difference between virgin and dismounted ones. Due to the aging, all dismounted polymer insulators had micro-cracks on the surface of weathershed and only the products of manufacturer B showed the reduction of OIT(oxidation induction time). But, there were no differences between virgin and dismounted products in contact angle and chemical structure. Therefore, it can be considered that the aging is only limited on the surface of dismounted polymer insulators and that NMR technique are very useful to evaluate the aging of polymer materials.

• 대한전기학회논문지
• /
• 제40권12호
• /
• pp.1242-1251
• /
• 1991

This paper is to investigate the tree growth phenomena and the characteristics of $\varepsilon$' and tan$\delta$ for the effect of ultrasonic wave on polymer insulation material. The conclusions are as follows. 1) As the pressure amplitude of ultrasonic wave is larger and its irradiated time is longer, tree inception voltage and its breakdown voltage in specimen are smaller, and tree growing is faster. 2) As the irradiated quantity of ultrasonic wave is more increased, the value of tan$\delta$ is larger, but the value of $\varepsilon$' is almost constant. 3) The effect by the pressure amplitude of ultrasonic wave is greater than that by its irradiated time on the insulation characteristics of polymer material.