Thermal Performance of Distribution Transformers in Underground Vaults: I - The Problem

This is the first of a series of papers that will explore, in depth, the heat transfer phenomena associated with the operation of distribution transforners in subsurface vaults. In it, the differences between vault and pole-top environments and the effects of these differences on transformer loadability are discussed. Heat transfer phenomena in the vault environment are described qualitatively, and the need for a general study to permit quantitative analysis is indicated. The plan of attack on the problem is described, and some conclusions are drawn from work already completed.