ABSTRACT
The basic principles used in the designs are discussed, starting from ideal transformer to a practical transformer which has exciting current, losses, leakage flux and impedance. The equivalent electrical circuits of practical unit are developed, and the calculation method of the value of elements in circuit are listed. The performances affecting power transmission network qualities such as efficiency and voltage drop at output terminals, its compensation methods and effect on design are detailed with a calculation example. To achieve economic designs, first, winding disposition such as axial split and radial split are compared in material cost with an example when both designs offer similar performances, and effect of winding space factor on material saving and cooling are discussed. Secondly, practical limits on current density and flux density, guidelines of economic design of active part are presented, and present practical designs are compared to the guideline. Finally, attention is given to special operation case of a three-phase unit having delta–delta, wye–wye and delta–wye connections.
