Air-To-Water Cooler

“Closed Air Circuit, Water Cooled” generator coolers

Short for “Closed Air Circuit, Water Cooled”, CACW coolers are ideal for cooling generators and large electrical motors, no matter the environment.

These products pass water at a lower-than-ambient temperature through an element, providing cooling to a generator or motor. CACW coolers are also commonly known as TEWAC (“Totally Enclosed Water to Air-Cooled”) coolers and may also be referred to as generator air coolers, motor air coolers or GM air coolers (short for Generator/Motor).

The advantage of CACW/TEWAC cooling is the closed-circuit design, from which they get their name. This prevents dirt particles and liquids from entering the primary cooling circuit, extending the life of the cooling element and reducing downtime of your equipment.

Improve the reliability of your equipment with this robust, closed-circuit cooling system.

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Using air-to-water coolers for generator and motor cooling

To understand how air to water heat exchangers are used as motor and generator coolers, let’s first consider how generators and similar machines are cooled in general. All electrical rotating machines (i.e. motors and generators) need cooling of the equipment rotor and stator.

CACW cooler designed and manufactured by Sterling Thermal Technology, on the top of a generator
CACW cooler on the top of a generator

Small electric motors and generators simply have fins on the outside of the motor frame. Larger machines generate much more heat, and direct cooling of the individual components is required.

This direct cooling (or “primary cooling”) is provided by passing air through passages within the machine core. The majority of the time, a fan on the machine shaft is used to create this air circulation. 

However, the primary cooling only moves the unwanted heat so far. This is where water-cooling comes in. A CACW generator or motor air cooler is installed to transfer the heat away from the electrical machine. This significantly increases the cooling system efficiency.

CACW for renewables designed and manufactured by Sterling Thermal Technology
CACW for renewables

It is with a full understanding of the processes involved that we, at Sterling Thermal Technology, can design and manufacture heat exchangers that meet our customer’s needs.

Learn more about partnering with Sterling TT.

Key benefits of CACW/TEWAC coolers

The most compact cooling option for large electrical machines

CACW coolers can use any available water supply, including river or seawater. However, some filtration or pre-treatment might be required. Closed-circuit cooling, which is already on the site, can also be used.

A closed-circuit design

We can provide levels of protection against solid and liquid ingress up to IP6.

Allows for increased equipment availability

We can build in cooler redundancy to ensure a very high degree of availability of the cooled equipment.

Can be made from robust materials

Reducing erosion and corrosion increases equipment life, so we use robust materials. Additionally, we can include double (safety) tube arrangements to protect the machine in case of tube failure.

icon of a quote mark“WEG has a long-standing partnership with Sterling Thermal Technology, and their CACW/TEWAC have proven to be reliable for various of our applications. Even for the most hazardous environments, we could always count with Sterling TT for a solution that can attend our demand.”

Anderson Fernandes, Global Director of High Voltage Motors and Generators
WEG Equipamentos Elétricos S/A

Important design considerations for generator and motor air to water coolers

Sterling Thermal Technology is a leader, who design and manufacture bespoke heat exchangers, including CACW coolers and all air coolers for generators and motors (GM coolers). We know that every installation is different. Below are some of the variables we would consider when designing a new product with a customer:

  • Generator construction: single or double tube.
  • Redundancy requirements for series and/or parallel operating arrangements.
  • Restrictions to the available air side pressure drop.
  • Limitations on the cooling water flow or permitted temperature rise of the water stream. Local Regulations can limit the rise allowed on the water before discharging back to the sea or an inland watercourse.

A CACW cooler can be designed with double tubes to avoid downtime.

Double tube rotating machine coolers

Transformer oil water cooler- Double tube -Design and manufacture by Sterling Thermal Technology
Double tube

Double tube electrical machine coolers are a specific type of CACW cooler. Double tube heat exchangers aren’t as compact but allow continued operation for a limited period in the event of inner tube failure.

If the tube is in contact with the water failure, the double tube feature ensures the leaking water is directed to a leak detection system outside the cooler enclosure. This gives the operator the opportunity to plan an intervention without immediately shutting down the machine or process

Flexible & bespoke 

CACW casing and element for oil and gas application manufactured by Sterling Thermal Technology

Our flexible heat exchanger software offers lots of design options to suit all applications and restraints. We can call upon a wide range of options to meet your thermal and mechanical specifications for any generator air cooler or motor air cooler your business needs.

Whether you are an original equipment manufacturer or an end-user, we can help with your heat exchanger needs. We can address the most stringent requirements with our design capabilities, system quality and production facilities. In addition, we are ASME Boiler and Pressure Vessel certified and produce both ’U’ & ‘UM’ stamped equipment. Contact us today.

If you want to know more about other types of heat exchangers we manufacture, visit our products and services page or contact us.

Customised heat exchangers

Over 100 years of design & manufacturing knowledge

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We customise our heat exchange solution to meet your requirements, so contact us today to discover the right equipment for you.

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