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As one of the most important equipment in power system, power transformer plays a major role in guarantying the safe and stable operation of power system. Among the faults in transformer, winding deformation takes a large part. Since 1970s, lots of method, such as Frequency Response Analysis, Low Voltage Impulse have been put into winding deformation detection. Among these methods, Vibration Analysis...
The paper quantitatively investigates the problem of derating the in-service distribution power transformers that supply heavy nonlinear balanced loads. The adopted computation method basis on the international standards and only requires the basic power quality parameters measured at the secondary winding of the transformer and its certified test report. Hence, by computing the major transformer...
Any failures in these equipments directly reduce network reliability and increase maintenance costs. Consequently, the preventive maintenance techniques are increasingly developed. In this regard, frequency response analysis is an appropriate method in order to diagnose any change which occurs in transformer physical construction. This contribution has been concentrated on fault diagnosis by use of...
Transformers are one of the main equipments of distribution systems. Increase in transformer loss is mostly the source of the damages, and caused by increased harmonic contents, especially current harmonic. These losses will result in an increase in temperature of various parts of transformer, especially its hot-spot temperature, and this temperature increase leads to insulation life reduction. Therefore,...
Heat dissipation is always a problem in large power transformers. Increased market competency demands for accurate determination of the thermal profile across the transformer. This paper presents a thermal model to simulate the thermal behavior of the electrical utility transformers. The thermal model is arrived at using the principle of thermal electrical analogy and the fact that the losses in the...
The paper investigates the effect of current harmonics in oil-rig's thruster drives, which are based on variable frequency AC induction motor drives. The electrical system in the oil rig consists of two 12 pulse phase shifting transformers having a relative phase shift of 15??, a frequency converter and an induction motor. The electrical system exhibits clean energy characteristics according to IEEE...
Phase Shifting Transformers (PSTs) are simple, reliable and economical means of controlling active power particularly if fast controls are not required for system stability. These transformers are built with unique connections of their windings, neither delta nor wye. Protection of such phase shifters is not well established. This paper presents original techniques for short-circuit protection of...
Transformers like most other commodities change in style from time to time as the years pass. It is the intent of this paper to delve back 40 years into the history of the Hydro-Electric Power Commission of Ontario and, in regard to transformers, compare the mode of thinking then with that of the present time, and to follow the changes that have occurred in four decades and the governing factors that...
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