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Efficient and safe cooling for generators and large electric motors in any climate

A closed air circuit air cooled (CACA) cooler removes the excess heat generated by large electric motors and generators. Ambient air passes through tube bores to provide cooling while the clean machine air passes over the outside of the tubes. The closed circuit prevents dirt particles and liquids from entering the primary cooling circuit, ensuring the lifetime of the equipment, is extended and optimised.

Key benefits

  • Effective – A CACA cooler is a simple but effective means of cooling a generator or motor in a dust-laden environment or where a water supply is not available or available at a premium.

  • Equipment availability – Cooler redundancy can be provided in the form of excess fan capacity to ensure a very high degree of availability of the cooled equipment.

  • Levels of protection against solid and liquid ingress up to IP56 can be provided for both the cooler / machine enclosure and ancillaries such as fans and instrumentation.

  • Robust – Materials can be selected to reduce corrosion and increase both the period between maintenance interventions and overall equipment life.


How closed air circuit air cooled coolers (CACA) work

All electrical motors and generators need an airstream to cool the equipment rotor and stator. Small electric motors simply have cooling fins on the outside of the motor frame. Larger machines generate much more heat, and direct cooling of the individual components is required.

Direct (primary) cooling is provided by passing air through passages within the machine air circuit. A fan on the machine shaft is used for air circulation in the majority of applications. A separate machine circuit cooling fan is installed when necessary to establish a consistent airflow. Machine circuit air is forced over the outside of the cooling tubes while ambient air is forced through the tubes. Axial fans are the most frequently used drivers for the ambient air supply although there are other design options available.

Every installation is different. Some design considerations are given below:

  • Generator / Motor construction – single or double end vented.
  • Redundancy requirements for fan operation.
  • Restrictions to the available air side pressure drop.
  • Limitations on the total installed power of air circulating fans
  • Corrosion potential of the environment.

We offer lots of design options to suit all applications and restraints thanks to our flexible optimising heat exchanger software. We can meet your thermal and mechanical specifications for the overall equipment requirement.

Sterling Thermal Technology can address the most stringent requirements with our design capability, quality system and production facility. We can configure CACA coolers for installation in hazardous and aggressive environments.

Download this rotating machine cooler CACA product datasheet as a PDF


If you feel you need another type of heat exchanger, visit our products and services page or contact us.

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We have used CACA coolers for a number of different generator installations. Sterling Thermal Technology has an understanding of our requirements which is second to none and their products have always met our expectations

Jon Southam, Global Commodity Leader, GE Power Conversion

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