Comparison of three-phase distribution transformer banks against three-phase distribution transformers

This paper compares the mass and the total owning cost (TOC) of three-phase distribution transformer banks against three-phase distribution transformers and the comparison is based on the minimum TOC. This is achieved through a field validated distribution transformer design program that automatically minimizes the objective function (TOC). Transformers compared in this paper are of shell-type, immersed in oil, and all are designed to meet the standard NMX-ANCE-2006-J116 in Mexico. The conclusion of this paper is that from the viewpoint of minimum mass and minimum TOC, in case of small-size transformers (smaller than 45 kVA) it is recommended to use three-phase transformer banks, which is in disagreement with transformer textbooks. This result is due to the fact that more mass is needed for transformer tank, oil and high-voltage conductor for three-phase transformer in comparison to three-phase transformer bank.