ABB’s oil-free transformers

ABB’s oil-free transformers

Vol. 6 Issue 4

Environment comes first with ABB’s oil-free transformers

Oil-filled transformers are the predominate transformer technology in use today. Nonetheless, hazardous risks to humans and the environment still exist such as fire and spills. ABB continues to develop oil-free transformers to eliminate these potentially catastrophic events.

Increasing environmental awareness and demand for electric energy coupled with modern urbanization trends have led ABB to develop innovative products for the supply, generation and transmission of power. Transformers are critical components in energy grid systems and are increasingly required to operate at reduced risk to humans and eco-sensitive environments. Transformers, which traditionally use mineral oil for insulation and cooling, allow energy to be transported from the production source to the location where power is needed. Increasingly located in metropolitan areas and near environmentally sensitive areas like harbors, transformers that use oil can pose safety and environmental challenges and generate additional long-term costs. Since the late 1980’s, ABB has sought alternative liquids and materials to reduce these risks. Oil-free transformers have continued to be a viable alternative in a growing number of niche markets, where ecology and safety drive choice.

Advantages of oil-filled transformers

Currently, oil-filled and oil-free (drytype) transformers are available; the obvious difference is the presence or absence of oil. Oil has ideal dielectric and cooling properties for use in transformers. Oil-free transformers rely solely on solid insulation i.e., polyester films, aramid fibers and epoxies as the dielectric material and ambient air for cooling. Though the dielectric capabilities of solid insulations are comparable to that of oil, transformer oils are orders of magnitude better at cooling than ambient air. This allows oil-filled transformers to be smaller, lighter, and produce lower noise levels than dry-type transformers of equivalent power ratings. These advantages have made oil-filled transformers the primary technology for today’s globally installed transformer market. Mineral oil for transformer use was successfully introduced in the 1970’s to replace the polychlorinated biphenyls (PCB) that were progressively banned due to their hazardous impact on human and environmental health. Despite the extensive safety history of oil-filled transformers, mineral oil has a relatively low flash point (170°C); a property that can result in catastrophic fires and explosive failures under rare conditions – causing concerns. During the late 1980’s ester oils, or seed oils, were investigated as an alterna tive fluid for transformers to diminish these risks. Natural esters have a higher flash point (330-360°C) than mineral oils; this allows the transformer to operate at higher temperature rises (up to a maximum 75°C rise) and greatly increases their fire safety ratings. Further, ester oils are renewable, non-bio-accumulating and non-toxic and are potentially biodegradable.