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A new on-line technique for monitoring the insulation condition of ac motor and generator stator windings is proposed. The approach uses a newly developed High-Sensitivity Current Transformer (HSCT) to precisely and non-invasively measure the differential current (e.g., the insulation current) of each phase winding from the motor junction box. Conventional differential current transformers (CT) used...
High-power electrical machines employed in mining and power generation are critical systems that require (long lifetime) high reliability and availability. That is why proper specification, design, operation and maintenance are needed together with condition monitoring and diagnostics. Concerning the application, it must be considered a comprehensive system design, including manufacturing, testing,...
In the paper, firstly, the insulation aging and insulation cut or crack fault models of DC feeder cable were established; then according to the characteristics of electrical and loads of DC feeder cable, the Rail- Voltage law and different DC current law were purposed in the orbital theory, and the feasibility of purposed law were discussed from engineering view. The results of analysis show that...
In this paper the basic management tools for asset and risk management were discussed. The structure and processes of asset management were shown. By the means of a risk matrix a good overview about the structure of the observed network is possible. For the equipment of high risk different measures can be applied to handle the risk. Besides preventing also reducing, transferring and finally accepting...
Corrosion of copper conductors due to Sulphur in transformer oil is a serious problem affecting both Power and converter transformers. The reactive and corrosive sulphur components are of very low order in fresh transformer oils but during service, some sulphur components are converted to reactive and corrosive forms which react with copper forming copper sulphide. Copper sulphide migrates from conductor...
The use of absorption/resorption currents to characterize the ageing state of electrical equipmentspsila insulation systems is well known. The maximal values and the slopes of these currents give important information regarding the paper-oil insulations for power transformers and energy cables, but these are also used for insulation systems of medium and/or high power machines. In general, the values...
While in service, the equipment is under long-term exposure to the operating voltage and short-term but repeated exposure to overvoltages in combination with other factors (temperature, mechanical stress, and adverse environmental state). This results in deterioration of the electric insulation and failure of the equipment due to insulation breakdown. To trace the dynamics of insulation state of the...
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