Distribution Transformers

Abstract

While there is no generally recognised definition, a distribution transformer may be defined as a transformer used to supply power, for general purposes, at final distribution voltage level from a higher-voltage distribution system. The minimum rating is usually regarded as 5 kVA, but the maximum is somewhat indefinite. For public supply purposes it is not common to use rating exceeding 1000 kVA, but industrial sub-stations frequently have higher ratings. 3 MVA is normally the practical limit for loading at medium voltage, as the impedance necessary to limit fault current to the usual switchgear ratings rises to impractical percentages at higher ratings.