Experts theorized that a Brushless Wound-rotor [Synchronous] Doubly-fed Electric Machine System (BWRSDF), which can symmetrically motor or generate with variable speed, provides higher efficiency, higher power density, higher torque density, and lower cost than any other electric machine system, including the permanent magnet electric machine system, but only with the discovery of a practical b...

Well known reasons for local failures in power transformers are caused by partial discharges (PD) in the electric insulation. Continuous deterioration over time increases the defect which finally can lead to a breakdown of the entire insulation. The importance of PD measurement is accommodated by standardized electrical measurement according to IEC 60270 [1] which is required for acceptance cer...

With the large scale developments of offshore windpower the number of underwater electric cables is increasing with various technologies applied. A wind farm is associated with different types of cables used for intraturbine, array-to-transformer, and transformer-to-shore transmissions. As the electric currents in submarine cables induce electromagnetic fields there is a concern of how they may...

Thyristor rectifiers are widely used in electric railways in order to control the speed. As a consequence of their usage in addition to substantial input lead current, an enormous amount of harmonics is injected into the grid. To avoid such harmonics as well as reactive power compensation, reactive power hybrid filters consisting of active and passive filters are utilized. Regarding different p...

In lifetime analysis of electric transformers, the maximum likelihood estimation has been proposed with the EM algorithm. However, it is not clear whether the EM algorithm offers a better solution compared to the simpler Newton-Raphson algorithm. In this paper, the first objective is a systematic comparison of the EM algorithm with the Newton-Raphson algorithm in terms of convergence performanc...

The computation program of the transient recovery voltages that appears across the terminals of a circuit breaker, after the low inductive current has been interrupted at the disconnecting no load high voltage transformers, using the routines set developed in Matlab is presented. The computation algorithm is based on the peculiarities of operation of the transformer. The computation program has...

power system overvoltages due to switching, lightning and other disturbances are the main problem for designers of the power transformers. once some frequencies of the incoming surges match with some of the natural frequencies of transformer winding, the resonance phenomenon is expected in transformer winding. the resonant overvoltages may destroy the insulation between turns and cause to insul...

A pair of ion cyclotron range of frequencies (ICRF) antennas in the large helical device (LHD), HAS antennas showed high efficiency in minority ion heating. However the low loading resistance must be increased to prevent breakdown in transmission line. Moreover, the voltage and the current around the feed-through must be reduced to protect it. For these purpose, we developed a design procedure ...

An electronic current transformer with a B-dot sensor is proposed in this study. The B-dot sensor can realize the current measurement of the transmission line in a non-contact way in accordance with the principle of magnetic field coupling. The multiple electrodes series-opposing structure is applied together with differential input structures and active integrating circuits, which can allow th...

Marina A. Tsili, Eleftherios I. Amoiralis, Antonios G. Kladas and Athanassios T. Souflaris 1 Faculty of Electrical & Computer Engineering, National Technical University of Athens, GR-15780, Athens, Greece (e-mail: [email protected], [email protected]) 2 Department of Production Engineering and Management, Technical University of Crete, 73100, Greece, (email: [email protected]) 3 Schneide...