Performances of distribution transformers installed in metallic enclosures-an Australian experience

In the last two decades, the Australian market has shown an increasing demand for packaged substations with three-phase distribution power transformers installed in metallic enclosures. The local electrical utilities and transformer manufacturers have developed many different designs based on unique specifications and a distinctive combination of construction features. Highly restrictive local environmental and urban planning regulations have resulted in the development of very compact packaged substations with extremely arduous service conditions for built-in transformers. The limited footprints and ever-increasing transformer ratings have resulted in reducing the ratio between the physical dimensions of the installed transformer and its rated power. This paper investigates Australian oil-immersed, ONAN cooled, and hermetically sealed distribution transformers rated 750-2000 kVA, highlighting their distinctive features: unique design, loading capability, reliability performances, and safety features. The paper is the result of extensive research conducted in a major Australian facility for the manufacturing and refurbishment of distribution transformers.