Escalating Global GDP (Gross Domestic Product)rate and Global Primary energy consumption demands reliable, uninterrupted andadequate power with high transmission efficiency.
In transmission systems, Transformeris a highest energy efficient device which operates practically throughout theyear at various load conditions. Therefore, total energy consumption intransformers (losses = core loss/no-load loss + I2R Losses + straylosses due to linkage of stray flux in structural parts like, clampingstructure, tank, etc.) have considerable impact on transmission efficiency. Intransformers, stray losses are more than 20% of total load loss that occurs instructural parts due to linkage of stray flux. The stray loss of thetransformers increases with transformer ratings. As a designer it is importantto accurately estimate stray loss components to further take advantage in totalowning cost of transformer through reduced losses. The paper presents use of UDEL(Unimpregnated densified electrical grade laminated) wood core clamparrangement for the core clamping structure to reduce stray losses andsubsequent heating effects.
The paper discusses development of 15 MVA, 66/11.55kV transformer with use of UDEL wood core clamps against conventional mildsteel core clamps. Results show that there are 28.2% reduction of stray lossand 4.5% reduction of total loss using proposed method.
This reduction of losscan be beneficial in terms of reduction in total owning cost of thetransformer. This arrangement also reduces the partial discharges in magnitude(average 27% reduction) by avoiding magnetic material in vicinity of highvoltage leads and yoke shunts. Structural analysis was also performed using FiniteElement Method (FEM) based software to check suitability of wood core clamp structureunder dynamic short circuit test condition. To ascertain ability of UDEL woodcore clamping structure, dynamic short circuit withstand test was conducted atnational laboratory and transformer had successfully cleared the test.