Different characteristics of artificially polluted high voltage composite insulators

Characteristics of leakage current, electrical field and surface resistivity of artificially polluted high voltage composite insulators for different composite materials in their structure, equivalent salt deposit density, electrolyte flow-rate and hydrophobicity are discussed, analyzed and presented in this paper. All these parameters are compared with conventional non composite insulators, too. Relativity of leakage current, applied electric field, electrolyte flow-rate and electrolyte conductivity to the environmental conditions are presented by the results of artificial pollution tests. Waveform, frequency spectrum and magnitude-phase diagram of leakage current of polluted insulators with different pollution densities and durations and applied voltages are presented. Surface resistivity of different insulators is compared regarding different kinds and densities of pollution. Electrical field causing flashover for polluted insulators as a function of the insulators' surface hydrophobicity and salt deposit density is also presented. Through the study, investigating the life time of being used insulators is achieved by measuring their leakage current, salt deposit density and surface resistivity and comparing with the test results

Hybrid filter applications for power quality improvement of power distribution networks utilizing renewable energies

A hybrid filter constructed of a shunt active filter and distributed passive filters used for power quality improvement in dispersed generation system is presented. The distribution system consists of several kinds of renewable energies as DG units where the power quality problems due to dispersed generation LV systems are introduced and the necessity of using hybrid filters instead of active or passive filters alone are discussed. The simulations are done with PSCAD/EMTDC for a distribution system with dynamic nonlinear loads and wind turbines, photovoltaic cells and diesel generators and several dynamic nonlinear load without any filters, with usage of just shunt active filter or passive filters and the hybrid filter structure, introduced in the paper. Studying and comparing the waveforms, harmonic contents and THD of the system current with different filter structures mentioned, proves power quality improvement by the applied hybrid filter

Different characteristics of semiconducting glazed insulators at artificially polluted conditions

Semiconducting Glazed Insulators are one of the most efficiently used insulators in contaminant areas. Several electrical and mechan ical tests take place under electrical and mechanical rest s are carried out to foresee the operation of these insulators in regions with high pollution. In attention to plenty of such tests that each one is being tested with a special way and different electrical, mechanical and en vironmental specifications, adding the results up and analyzing them has a special importance. In this paper, comparing the operation of this kind of insulators with conventional porcelain insulators in different artificially polluted conditions and related indexes in determining the operation of these insulators in different conditions of pollution is achieved

Analysis of grounding system for the power distribution systems of electrified railways with safety considerations

No abstract availabl

Parameters for the selection of overhead contact system of electrified railways studying their transients overvoltages characteristics

No abstract availabl

Application of renewable energies as distributed generation in electrical system

No abstract availabl