Distance protection of big network transformers

This paper shows how to set the distance protection of a big network transformer for correct measuring all kinds of a short circuits inside and behind this transformers - YNauto / d1 (400 / 220 / 35 kV, 400 or 220 / 110 / 10,5 kV). There is a problem with influence by their tertiary delta winding. In the paper is the derivation of impedances and method for distance protection setting.