The problem of gliding discharges on high voltage equipment is faced in practice, coith inclined interface, such as cable terminations, bushings.
Many researches present very important results about the relationship between the applied voltages and
this partial discharge . But studies about the insulation systems that have small cross capacitor or that have air gaps are limited, considering many points, one of them: the discharge procedure looks
like the partial discharge in insulators, with longitudinal interfaces.
Achieving precise relationships for such systems and finding the actual discharge behavior gives high scientific efficiency and important application for design of high voltages devices, especially when high voltages, which are changing with time voltage like alternatring and lightning voltages, are applied.
The polluted insulators problem is one of the most important cases, that faces the electrical networks especially in Syrian Arab Republic because the sources of pollution expand more and more, On the other side, the electrical power supply is related
to the operation of all commercial and daily sectors.
The environmental pollution on the insulators generally causes general breakdowns in the electrical power supply networks of wide areas, This makes great economical losses in all sectors that are related to electrical network.
In this research, the distinct values of insulators pollutions are defined. We then find the relationship between the mentioned values and flashover voltage of polluted insulators in the laboratory. The results of the tests apply on the natural polluted insulators in the outsides. Finally, comparison measurements are made on naturally polluted insulators, and the appropriated procedures to limit the pollution effects .
The aim of this paper is to discuss the operation of an all silicon-based solution for the conventional Marx
generator circuit, which has been developed for high-frequency (kHz), high-voltage (kV) applications
needing rectangular pulses. The conven
tional Marx generator, for high-voltage pulsed applications, uses
passive power components (inductors or resistors), to supply the energy storage capacitors. This solution
has the disadvantages of cost, size, power losses and limited frequency operation. In the proposed circuit,
the bulky passive power elements are replaced by power semiconductor switches, increasing the
performance of the classical circuit, strongly reducing costs, losses and increasing the pulse repetition
frequency. Also, the proposed topology enables the use of typical half-bridge semiconductor structures,
and ensures that the maximum voltage blocked by the semiconductors equals the power supply voltage
(i.e. the voltage of each capacitor), even with mismatches in the synchronized switching, and in fault
conditions. A laboratory prototype with two stages of the proposed silicon-based Marx generator circuit
was constructed using IGBTs and diodes, operating with about 1000 V dc input voltage and 10 kHz
frequency, with different rise times.
The use of cross-linking polyethylene was increased, especially for the
medium & high voltage electrical cables instead of paper and oil insulating
materials. The radiated low density polyethylene is the best technique in the
process of cross-link
ing instead of chemical method.
The purpose of this study is to find the relation between mechanical
properties of polyethylene samples and the dose rate of irradiation to cross –
link the polyethylene materials and to get the best properties.
This paper illustrates also the important results, that we have obtained in
this study.
