Aspects Regarding the Design, Realization and Testing of an ONAN Special Transformer Used in the Electrical Distribution Networks

The purpose of this paper is to present the processes from designing stage to testing of a three-phase transformer with special construction <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$250 \text{kVA}-20 \text{kV}(10 \text{kV} / 0.4 \text{kV}$</tex>, being intended to operate in the electric distribution networks. In this moment some of these networks have a rated voltage of 10 kV, but in the future they will be replaced with 20 kV ones. For this a cheap solution without additional costs is needed.