Dielectric properties of mica‐alumina combined insulation at high temperatures

Ishida, M.; Ikeda, Yasuyuki; Naohara, Nobuyuki; Mitsui, H.; Kumazawa, Ryoji; Kuroki, Toshitaka

doi:10.1002/eej.4391160302

Cited by 4 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the voltage application experiment, the ac current slowly increases with time and suddenly increases immediately before dielectric breakdown, leading to breakdown [2]. Figure 6 shows an example.…”

Section: Resultsmentioning

confidence: 99%

“…However, the coefficient k for diffusion of the metal into the insulation layer has a temperature dependence expressed by Eq. (2). When the voltage is constant, the numerator on the right-hand side of Eq.…”

Section: Discussionmentioning

confidence: 99%

“…Accordingly, the authors et al have developed an insulation composition with mica as the main insulating material. Using this insulation composition, they carried out research on the dielectric properties and dielectric deterioration at high temperature [2,3]. As a result, it was learned that copper diffusion into the insulation layer of the conductor contributed to the deterioration of the insulation [4,5].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of the voltage life of mica-alumina composite insulation at high temperatures

et al. 1999

View full text Add to dashboard Cite

Experiments and investigations were carried out on the voltage life of a bar‐coil model with a nickel‐plated copper conductor covered with mica‐alumina composite insulation at a temperature range of 550–850 °C. Diffusion of copper into the insulation layer was observed on the specimens aged for a long period. Insulation with mica paper gave faster diffusion speed and shorter voltage life than insulation with mica flake. The diffusion speed became higher with an increase in temperature. The ac current gradually increased with aging time and increased rapidly just before breakdown. There was the relationship I = aEn (a, n: constants) between ac current I and applied stress E, and n was approximately equal to 1 in the region where thermal unbalance did not occur. Arrhenius's law held in the relationship between ac current and aging time. Therefore, the breakdown mechanism might be that the effective insulation thickness decreased due to copper diffusion into the insulation layer and the ac current increased gradually until thermal breakdown in the last stage. If copper diffuses into the insulation layer, even with no voltage application, the aging time required to decrease the breakdown voltage to a certain level (the voltage life) obeys Arrhenius's law. If the voltage life is dominated by diffusion into the insulation layer, the activation energy for voltage life in the aging test becomes twice that for diffusion, both with and without voltage application. © 1999 Scripta Technica, Electr Eng Jpn, 129(4): 24–31, 1999

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Investigation of the voltage life of mica-alumina composite insulation at high temperatures

et al. 1999

View full text Add to dashboard Cite

show abstract

“…The abundance, the relatively low cost of mica and the inherently good electrical properties of this mineral are factors, which have maintained merest in the use of mica in various applications. A mica-alumina combination is selected for the insulating system at temperatures higher than 500 o C. The aging condition was to apply 1.5 k.v.as voltage in nitrogen atmosphere at 550 o C [6].…”

Section: Introductionmentioning

confidence: 99%

Electrical Properties and Infrared Studies of Heated Mica Sheets

2002

Egyptian Journal of Solids

View full text Add to dashboard Cite

Dielectric constant (έ), dielectric loss (ε") and (tan δ) have been measured for heated Mica sheets at different temperatures (200-900 o C) for 2 hours in the frequency range (0.1-100KH Z). It has been found that the dielectric constant and dielectric loss are nearly stable till 600ºC but showing an increase at 800 and 900 o C. The dielectric loss and tan δ show maximum 800 and 900 o C. The activation energy values of dielectric relaxation have been calculated for mica sheets for the latter temperatures. It was observed that the activation energy values go on increasing with increasing heating temperature from 800ºC to 900ºC. The resistivity of mica sheets was studied also as a function of temperature in the range (30-70ºC) for the samples heated at 800ºC and 900ºC over frequency range [0.1-100 KH z ]. It was found that the resistivity increases with temperature and decreases with frequency. The resistivity at 900ºC is higher than 800ºC overall the range used. Infrared spectra were studied to link the influence of the structure of heated mica with their thermal behavior.

show abstract

Finite magneto-static field effect on the excitation of THz hybrid modes in an elliptical metallic plasma waveguide with two energy sources

Safari

Jazi

2017

Physics of Plasmas

View full text Add to dashboard Cite

The effect of finite magnetic field on the excitation, generation, and amplification of slow electromagnetic waves at THz frequency in a magnetized plasma waveguide with elliptical cross section is investigated. In configuration mentioned above, there are two electron beams with opposite directions as energy sources, and the role of magnetic field power on the appearance of the number of dispersion branches is analysed. It is shown that with increasing magnetic field, the field profiles of hybrid waves are increased in regions where the interaction of waves and electron beams are optimized. It is also shown that by applying the magnetic field, generation of THz frequencies can be easy to obtain in comparison to the unmagnetized case. In other words, by applying a finite magnetic field, better THz excitation occurs in the absence of high accelerating voltage. Increasing growth rate which can be achieved with increasing static magnetic field is also investigated. In this paper, because of high longitudinal velocity of electron beams, the effect of finite magnetic field on the fluctuations of electron beams is considered negligible.

show abstract

Dielectric properties of mica‐alumina combined insulation at high temperatures

Cited by 4 publications

References 0 publications

Investigation of the voltage life of mica-alumina composite insulation at high temperatures

Investigation of the voltage life of mica-alumina composite insulation at high temperatures

Electrical Properties and Infrared Studies of Heated Mica Sheets

Finite magneto-static field effect on the excitation of THz hybrid modes in an elliptical metallic plasma waveguide with two energy sources

Contact Info

Product

Resources

About