Disadvantages Of Partial Discharges

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2.8 Partial discharge Analysis Partial discharge theory involves an analysis of materials, electric fields, arcing characteristics, pulse wave propagation and attenuation, sensor spatial sensitivity, frequency response and calibration, noise and data interpretation. It is obvious from the above that most plant engineers will not have the time, or available energy, to pursue such a course of study In an effort to promote a better understanding of partial discharge (PD), this paper attempts to provide simplified models and relate the characteristics of these models to the interpretation of PD test results. First, we will present a few technical concepts relating to partial discharges. Partial Discharge can be described as an electrical pulse or discharge in a gas-filled void or on a dielectric surface of a solid or liquid insulation system. This pulse or discharge only partially bridges the gap between phase insulation to ground, and phase to phase insulation. These discharges might occur in any void between the copper conductor and the grounded motor frame reference. The voids may be located between the copper conductor and insulation wall, or internal to the insulation itself, between the outer insulation wall and the grounded frame, or along the surface of the insulation. The pulses occur at high frequencies; therefore they attenuate quickly as they pass to ground. The discharges are effectively small arcs occurring within the insulation system, therefore…show more content…
This usually occurs on the insulation surface. These discharges can bridge the potential gradient between the applied voltage and ground by cracks or contaminated paths on the insulation surface The above can be illustrated by development of a simplified model of the partial discharges occurring within the insulation system. Figure 2.8.2 – Surface Partial
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