• The Journal of the Acoustical Society of Korea
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• v.34 no.4
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• pp.288-294
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• 2015

The fiber optic Sagnac interferometer is well established as a sensor for detection of physical perturbations such as acoustic and vibration. In this paper acoustic signals generated in the cylindrical cavity submerged in transformer oil were measured by the fiber optic sensor array in one Sagnac loop. Two different external sound frequencies, $f_1$ and $f_2$, were applied to the sensor array simultaneously by using piezoelectric with frequency range from 5 kHz to 90 kHz. Based on the experimental results, fiber optic sensor detected harmonic series of applied sound frequency such as $f_1$, $f_2$, $2f_1$, $2f_2$, ${\mid}f_1-f_2{\mid}$, ${\mid}f_1+f_2{\mid}$. Suggested fiber optic sensor array can be applied to monitor physical quantities such as internal sound pressure and vibration due to partial discharge in the real electric transformer system.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.267-269
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• 1997

The electrical properties due to the Benzotriazole(following as BTA) additive in fluids for insulating and cooling the ultra-high voltage transformer is studied in this paper. Specimen having the several contents of BTA, such as 5[ppm]. 10[ppm] and 30[ppm] is used in order to investigate the characteristics on volume resistivity in case of fluid flow in experimental device made in lab. Volume resistivity is decreased with an increase of fluid flow velocity and increased with BTA content in low temperature region, but volume resistivity of specimen contained BTA 10[ppm] is the largest thing over $30[^{\circ}C]{\sim}50[^{\circ}C]$ than the others in experiment.

• Electrical & Electronic Materials
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• v.10 no.8
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• pp.756-762
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• 1997

In this paper the change of electrical properties of transformer oil due to electron beam irradiation is investigated. The specimens are produced with a some different dose of 0.5[Mrad], 1[Mrad] and 2[Mard] except for original specimen. The physical properties of each specimen is analyzed by using the FT-IR spectrum. So it is confirmed that carbonyl groups are increased according to the increase of electron beam dose and also that the nitric compounds are disappeared. The magnitude of dielectric dissipation factor appears maximum value by the contribution of dipoles and ions in the low temperature low voltage region and it is stable due to the saturation of carriers in the high temperature high voltage region in the electric conduction characteristics. Volume resistivity is also measured one of original specimen is larger than irradiated specimen.