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Title: Development of a distribution transformer not subject to destructive failure. Final report

Technical Report ·
OSTI ID:5199144

Conventional distribution transformer insulations include a formvar-type coating on the copper wire, kraft paper barriers between the layers of wire and kraft paper barriers between sections, all saturated with a dielectric oil. The combination of the mechanical, electrical, and thermal properties of the insulation systems makes this an efficient effective composite for use in the millions of distribution transformers on line today. A deficiency of this system is the occasional occurrence of destructive failures by these transformers in the field. For a number of reasons the insulations can break down electrically or thermally. The arcing produced can generate gases which greatly increase the pressure within the enclosure and can blow off the cover, bushings, or rupture the tank. Hot and sometimes burning oil ejected by such failures of pole-mounted and pad-mounted transformers can result in property damage, environmental contamination, or personal injury. Corrective measures to reduce or eliminate those types of failures such as strengthened tanks, pressure relief valves and current limiting fuses have not always been entirely successful or cost effective. The substitution of inorganic high temperature insulations for the oil-paper system in present transformer designs was studied. Various types of ceramic, glass, and other inorganic materials were studied. Processing techniques necessary to apply these materials to a transformer were developed. A variety of design configurations for the transformer were studied, with emphasis on developing processing methods needed for the use of presently available materials.

Research Organization:
McGraw-Edison Co., Franksville, WI (USA)
OSTI ID:
5199144
Report Number(s):
EPRI-EL-2484; ON: DE82905814
Country of Publication:
United States
Language:
English