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Motor and Generator Coolers

We supply surface air coolers, exciter coolers, and bearing oil coolers to remove heat from large electrical machines such motors, generators, and synchronous condensers. If you know your performance requirements, you can contact us by requesting a quote.

Motor Coolers


Motors that generate large electrical losses in the form of heat are required to be cooled. Often these motors are cooled by using ambient air but in an environment where the available cooling air temperature is high and / or the application is dusty, ambient air may not be the most suitable way to cool a motor. In these applications, Totally Enclosed Water Cooled (TEWAC) Motors are used where the motor air is circulated over a water cooled heat exchanger.

Our partner company, Unifin International manufactures a unique motor cooler that uses a double tube “leak detector” design that protects motors from catastrophic water damage in the event of a tube leak. Click Here for information about Unifin’s Leak detector design.

One of the key design features of both motor coolers and generator coolers is the removable cover plate. This feature allows access to the tubes for inspection, mechanical cleaning, repair or plugging without removing the cooler from the motor or the generator. When designed with proper gaskets and machined surfaces this feature can provide leak free accessibility to the water side of the cooler.

Common Applications:

  • Large Pump Motors
  • Compressor Motors
  • Offshore Drilling Rig Motors
  • Pulp Refiner Motor Coolers
  • Mining Applications

Generator Coolers


Electrical generators produce not only electricity but they also produce heat from friction losses in the bearings and from conductor resistance in the core and windings. Adequate heat removal is not only essential to allow for the generator to meet capacity but is also critical in maintaining the remaining operating life of the generator, or in some case (with proper analysis) increase generator output. 

Hydroelectric Generator Cooler:

Most of the electrical losses in a generator are transferred in the form of heat. Keeping the core and windings of the generator at the dictated design temperature is critical. Failure to adequately remove this heat can result in derating the generating unit, reduced lifetime, damage to components or failure. 

The heat generated by the electrical losses is removed by Unifin International’s removable cover plate (RCP) type coolers which allow easy mechanical cleaning of the tubes. These units are custom designed for the installation to match available space and thermal conditions. They can be thermally size (or re-rated) for changes in the cooling system or to provide increased cooling capacity for life extension or increased generation capacity. 

Hydrogen Cooler:


Large Generators such as those at coal, gas and oil-fired plants or at Nuclear power plants often operate in a hydrogen blanket because hydrogen provides better cooling than air and also results in less windage losses due to friction.

Cooling the hydrogen in this type of generator demands special skills in; thermal design, mechanical design, manufacturing tolerances, cleanliness and sealing. Since these coolers are installed directly inside the generator, Hydrogen coolers are critical equipment for the safe operation of the generating unit. Unifin International and its operating units have been manufacturing generator coolers for generator manufacturers and end users since the 1920’s .

Bearing Oil Coolers


Natural Oil Flow


Forced Oil Flow


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