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We propose a novel method to measure the dielectric constant of insulating liquids using a laser beam. We use a research ellipsometer composed of a laser source, a polarizer, a compensator, a sample holder, an analyzer, and a photo-detector. The laser beam passes through the oil sample and accordingly undergoes polarization changes of its electric vector components; parallel and perpendicular to the...
Samples of two types of insulating oil used in transformers and switch-gear components in Egypt are experimentally tested to determine the breakdown-change of their dielectric constant and of their breakdown voltage. A standard oil tester is used to apply high voltage to the samples at two different rates and two different time intervals. The breakdown voltage of each sample is measured at the two...
An experimental study on the combined γ-radiation and heat effects on the electrical properties of transformer oil is presented. Several samples of fresh unused transformer oil of the type used in Egypt is irradiated in a γ-cell for different time periods, at the same radiation conditions. Each sample, one at a time, is then raised to a different pre-specified temperature. At this temperature, we...
Photo-emission during the breakdown processes of an insulating oil is recorded and analyzed. A standard oil tester is used to energize the gap at a constant rate of rise of the applied ac voltage of 50 Hz. Standard spherical electrodes of a radius of 25 mm and a spacing of 1.75 mm are used. A laser beam is employed to adjust the inlet iris of a photo-multiplier telescope to the center point of the...
Ellipsometry is a technique that uses a light beam to probe the surface or volume under test. It is a very accurate technique to measure the complex dielectric constant ϵ* (= square of refractive index) of materials, and the thicknesses of overlaying films and their ϵ*'s.
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