Although Alaska is the largest state in the U.S., its population density is among the lowest. It's estimated that more than 80 percent of the towns and villages in the state's interior depend solely on diesel engine generator sets to supply electric power. And because winter temperatures in the interior can plunge to as low as -60 [degrees] F, genset reliability is obviously critical.

Along with the bone-chilling cold itself, challenges to dependable gen-set operation in winter include fuel gelling, buildup of sheet ice inside intake air flues and ductwork, severe wind and snow.
One consistent problem with generating sets operating under these conditions is thermal shock. Although a generating set and its ancillaries are typically contained within a climatized building or enclosure, the engine cooling radiator is often located on the building's roof and exposed to outdoor ambient temperatures. Consequently, when the engine's thermostat opens and sends hot coolant to the radiator, thermal shock can break the connection between the radiator core and header. Not only does this cause gen-set shutdown due to coolant leakage, but it can also contaminate the environment.

"Years ago, leaking generating set radiators were common in supplying electric power to the Alaskan bush," explained John Cameron, manager of Pacific Detroit Diesel-Allison's Anchorage, Alaska, operation. "Cooling system failures resulted from both the severe cold and less-than-desirable modes of gen-set transportation. Thermal shock in the cooling systems of stationary electric power plants caused conventional radiators to crack and fail - and always at the most inopportune times.