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A significant proportion of power transformers installed across the world approaching the end of their designed life. One reason for a power transformer to reach the end of its life is that its paper insulation has degraded to the point where it has lost its tensile strength. The rate at which paper degrades is mainly related to the temperatures within the transformer and the water content of its...
In this paper a review is given of computing procedures for evaluation of the absorption current and recovery voltage measurements in dielectric systems. The method based on the recovery voltage measurement is treated in details and compared with some selected methods used in this field. All computing procedures were applied to the dielectric data acquired on aged PVC cables. In the final assessment,...
High voltage bushing forms an essential part of a power transformer and its insulation condition is of high importance in a transformer's reliability. Transformer failure statistics indicate considerable contribution from bushing failures, which makes the monitoring of power transformer bushings essential. Several off-line and on-line methods are available for condition assessment of these components...
A technique capable of utilizing voltage waveforms containing harmonics for measurements of dielectric response over a range of frequencies is presented. It has proved useful in several applications and offers high accuracy and flexibility. This paper presents measurement of the changes imposed by electrical treeing in the dielectric properties of LDPE samples and shows that the capacitance increase...
Transformer oil-paper insulation system is continuously subjected to thermal stress which is a key factor inducing its deterioration. Dielectric response of oil-paper insulation in frequency domain is being gradually used by power utilities for assessing the condition of transformer oil-paper insulation system, and the Frequency Domain Spectroscopy (FDS) measurement is a promising method. It is important...
The condition evaluation of electric power equipment gained very much importance in the last years. Generally it forms the basis of maintenance strategy, risk evaluation and the decision over renewal or reinvestment. Dielectric measurements are a very important tool for the technical diagnosis of electric insulation systems like generator bars of rotating machines. Beside partial discharge and dissipation...
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