Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : eddy current

Non-Sinusoidal Loading Effect on Oil Immersed Power Transformers

Mohammed k.Edan

Engineering and Technology Journal, 2011, Volume 29, Issue 12, Pages 2386-2400

Transformers are usually designed for nominal frequency and sinusoidal load current. Nowadays, usage of non-linear loads such as power electronics loads has extremely increased. These loads produce harmonic currents, which induce additional losses in transformer windings and other transformer parts and cause temperature rise, and ultimately can cause insulation deterioration, ageing and finally fast failing. The purpose of this paper effort to quantify the increasing in transformer
losses due to harmonic load current and the corresponding temperature rise in
transformer and study the effect of harmonics on loss of insulation life, total ownership cost of transformer, capacity of transformer and oil viscosity. An eddy current harmonic loss factor for transformer windings and harmonic loss factor for other stray loss are presented and used to calculate the transformer losses under harmonic load currents. The impact of transformer winding conductor size on
winding eddy current harmonic loss factor is presented. Three loads with different amount of harmonic content of load current are proposed in this paper.

Electromagnetic Interference Caused by Iraqi 400kV Transmission Lines on Buried Oil Pipelines

Suad I. Shahl

Engineering and Technology Journal, 2010, Volume 28, Issue 24, Pages 6937-6953

The electromagnetic interference caused by power transmission lines to oil and gas buried pipelines is under investigation for many years. Especially during fault conditions, large currents and voltages are induced on the pipelines that may pose danger to working personnel or may accelerate the corrosion of the pipelin’es metal. In this research, the Joule effect of eddy currents induced in the oil buried
pipelines due to the magnetic fields produced by nearby 400kV transmission lines in the South of Iraq have been computed. A computational model based on 2D finite element approach to calculate the heat generation rate. The influence of different earth resistivities for homogeneous earth model during steady state and
fault conditions is analyzed. A mitigation system using mitigation wires has been simulated to reduce induced eddy current heating effects to the safety limit.

Analysis of Induction Cooker Coil

Hassan A. Al-Ssadi; A.K.M. Al-Shaikhli

Engineering and Technology Journal, 2010, Volume 28, Issue 21, Pages 6288-6305

The use of induction heating in industrial applications is old and wide. In recent years, this technology was entered to domestic use. This research deals with the analysis and applications of induction heating for cooking food, as these techniques have safe and economy, as well as cleanness and the atmosphere of work comfortable. Knowledge of the electrical resistance of induction heating system is very important to designers working in the high frequency-supplies. This research also analyzes and studies this resistance, by used solid, litz and twisted
wire, and offers simplification of equations derivation help anyone interested in this subject. The MATHCAD V.14 program has been employed to obtain the results. The results presented as general curves for three types of wires (solid, litz and twisted wire) so that a designer can use them without lengthy and complex calculations.