Hawaiian Electric Co. (HECO) is the first utility in the world to install an ABB Solid Insulation Distribution Transformer (SIDT) on a pole. Located in an environmentally sensitive location next to a waterway, the use of the SIDT eliminates the possibility of an oil spill that could create serious negative publicity and cost as much as US$75,000 to clean up.

SIDTs were developed by CITEQ, a joint venture between Canadian utility Hydro-Québec and ABB. The windings are fully impregnated and the magnetic core fully coated with epoxy resin. No liquid or gas dielectric medium is used. This eliminates the possibility of an oil spill or catastrophic explosion. Their fiberglass-epoxy resin shell makes them waterproof, corrosion-resistant and virtually maintenance-free. With primary bushings and flexible secondary leads molded directly into the unit, SIDTs are hermetically sealed and can be installed in virtually any location or position. Of the approximately 500 units installed in North America, some are directly buried or submerged in saline water.

Seeking to eliminate the oil and fire hazards of conventional oil-filled transformers, HECO installed its first SIDT in a high-rise building vault in mid-2003. It is now developing standards to install SIDTs in residential areas as an alternative to traditional oil-filled pad-mount and submersible transformers.

HECO thought it was natural to extend SIDT benefits to pole-mounted applications. It worked with ABB to determine transformer orientation, color, primary termination and mounting. More pole-mounted installations are planned for HECO and its subsidiaries, Hawaii Electric Light Co. Inc. and Maui Electric Co. Ltd.