Comparison of three-phase transformers with rectangular and circular rod contour of planar laminated magnetic cores (mass and cost indicators)

Abstract

Purpose. In transformers of mass productions low power planar magnetic cores with a rectangular cross section of rods are used. With a capacity of more than 16 kV∙A and high power, transformers with circular forming loops of rods and winding coils are produced. In recent decades, in order to reduce the complexity of manufacturing, the transformers power with rectangular sections of magnetic circuits cores has increased. However, there is no analytical study of the effect of replacing circular core loops and winding coils on rectangular ones. Methodology. The influence analysis of the change in the rods configuration on the mass and cost is performed by the method of invariant and structural-parametric synthesis of electrical machines with optimized dimensionless indicators. Results. Indicators values comparison gives an objective assessment of the advantages or disadvantages of the considered variant with respect to base analog. Originality. It has been established that use of rectangular sections of rods and copper or aluminum windings forming loops in an electromagnetic system leads to an improvement in three-phase transformer mass performance of a relative to the analogue with circular generating loops. The change in mass-value indicators depends on the rods filling factor of the circular contour with rectangular packages of electrical steel. Practical value. Three-phase planar electromagnetic systems of 1–110 kV voltage class with rod cores and circular and rectangular generating circuits are distinguished by minimal mass and cost indicators by 5,76–5 % and 7,8–6,6 % and 2,5–2,3 % and 2,93–2,7 % with the rods filling factor 0,786 and 0,925 in variants with copper windings. These indicators, when used in aluminum windings, differ by 4–3,54 % and 6,3–4,9 % and by 1,8–1,75 % and 2,67–2,07 %.