Paper analyzes a sparking phenomena that were observed on power transformers during their first few energizing. Sparks occurred the flange between tank cover and side, in spite of fact jumper (copper link) was used. The phenomenon from different manufacturers, with various transformer ratings, three or five limb core. proposes simple electromagnetic model for analyzing phenomena. Three-phase is...

A current probe has been designed which allows measurement of ns;pulsed currents in high voltage environments. The probe consists of a current transformer and an optical transducer. The transformer coil in a metallic torus is considered as a slow-wave transmission line and is terminated with its wave impedance. In this mode of operation current pulses shorter than twice the transit time of the ...

This paper presents the use of Artificial Neural Networks (ANN) as a pattern classifier for the combined differential protection of generator-transformer unit with an aim to build a backup protection system to improve the overall reliability of the system. The proposed neural network model is trained and tested with an efficient Resilient Back propagation (RPROP) algorithm and Genetic Algorithm...

In this paper, a new algorithm based on processing differential current harmonics is proposed for digital differential protection of power transformers. This algorithm has been developed by considering different behaviors of second harmonic components of the differential currents under fault and inrush current conditions. In the new method, a criterion function is defined in terms of the time v...

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...

Power system protective relaying systems are striving to meet the demands of systems which are ever increasing in complexity. . High-speed digital relays must make decisions while the power system is still in transition. Understanding the operation and performance of microprocessor based relays requires new engineering tools. Current transformer (CT) and relay modeling are practical tools to ev...

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...

Transformer insulating oil nanofluid is made to improve dielectric and thermal properties of the oil by employing nanoparticles with proper properties. In the current work, nanofluids based on transformer mineral oil were prepared by three procedures using diamond nanoparticles with high thermal conductivity, as well as high dielectric properties. It was tried to consider the impacts of surfact...

Magnetic core saturation of transformers and rotating machines generate harmonics. Harmonics are integer multiples of the fundamental frequency. Harmonics is caused by nonlinear devices in the power system. Due to the non-linear loads, power frequency harmonics exist mainly in distribution systems. The current harmonics cause voltage harmonics, hence resulting in nonsinusoidal supply voltage in...