Calculation of current distribution in transformer windings

The calculation of current distribution in transformer windings is essential for calculation of losses, temperature rise, short circuit stresses and so on. An important case is the calculation of the current distribution in a Y-/spl Delta/ transformer in the case of a line-to-line short circuit of the /spl Delta/ side. The transformer with a tertiary winding in YY/spl Delta/ connection, with the possibility of feeding from both Y sides, is another interesting case. It is well known that the short circuit current in the case of a line-to-line short circuit is less than the three phase short circuit current. The thermal stresses and the mechanical stresses in the windings of a Y-/spl Delta/ transformer in the case of a line-to-line short circuit are as high as the stresses in the case of a symmetrical three phase short circuit. The current distribution in the windings of a Y-/spl Delta/ transformer is calculated. It is assumed that the sum of the ampere-turns of the windings on each leg of the core is zero. The line-to-line short circuit current distribution is then calculated explicitly. A general case for the calculation of voltage and current distributions in transformer windings of any connection is then discussed.