Cooling of electric motors
Why electric motors need to be cooled
The cooling of electric motors is a decisive factor for their performance, reliability and service life. Heat is generated during the operation of an electric motor, primarily due to electrical losses in the windings and mechanical friction. Without sufficient cooling, this heat can build up inside the motor and lead to overheating. Too high a temperature can have serious consequences: The insulation of the windings can be damaged, leading to short circuits or total failure. The motor bearings are also sensitive to heat, as lubricants lose their effectiveness at high temperatures.
An overheated motor is not only prone to faults, but can also become a fire hazard, causing considerable safety risks and costs. In addition, the temperature has a direct effect on the service life of the motor – a rule of thumb says that the service life of the insulation is halved for every 10 °C increase in temperature. Conversely, this means that a well-cooled motor lasts longer and can be operated closer to its maximum performance limit without suffering damage. This means that higher performance can be achieved from a motor with the same volume.
Various methods are used to cool electric motors. The most common is air cooling, in which fans dissipate the heat from the motor surface. In more powerful or compact systems, such as electric vehicles or industrial systems, water or oil cooling systems are also used, which enable even more effective heat dissipation. Overall, efficient cooling makes a significant contribution to the reliable, safe and long-lasting operation of electric motors.
Air cooling of electric motors in the industrial sector
Basic principle of air cooling
With air cooling, ambient air is directed over the engine to cool the heated surfaces - especially the engine housing. The cooling capacity depends on how quickly and how much air flows over the hot areas.
Typical structure of an air-cooled industrial motor
Cooling fins on the motor housing The housing is usually equipped with fins or cooling fins that increase the surface area. This allows more heat to be dissipated into the ambient air.
Axial or centrifugal fan
A fan wheel is often mounted on the rear of the motor (opposite the shaft output side) - either axially (like a propeller) or radially (like a worm wheel). This is often driven directly by the motor shaft and generates an air flow along the housing.
Air duct / fan cowl
A fan cover or protective grille ensures that the air is directed over the cooling fins before it flows out again. This ensures a defined air flow and improves cooling efficiency.
Sealed design (e.g. IP55)
In industrial applications, electric motors are often protected against dust and splashing water, i.e. they are housed in a closed enclosure. The air then flows over the outside of the enclosure rather than through the interior of the motor – this is why it is referred to as surface cooling.
Example: Type IC 411
A common standard for air-cooled industrial motors is the IC 411 design in accordance with IEC 60034-6. This means:
- The fan is external and mounted on the motor shaft.
- The air is routed via the housing with cooling fins.
- Cooling is achieved through self-ventilation – without external ventilation systems.
Typical areas of application
- Conveyor systems
- Pump systems
- Compressors
- Machine tools
- Blowers
- Production lines
It is particularly suitable for applications where the ambient temperature is controlled and no extreme contamination or temperatures occur.
Construction of an air-cooled solution with ebm-papst fans
Mounting the fans
Axial or radial fans from ebm-papst are mounted either directly on the housing of the electric motor or in a separate cooling channel. The choice of fan type depends on the design and the required air flow rate.
Airflow routing
The fans generate a targeted air flow over the surface of the motor or through special cooling fins on the housing. These fins increase the surface area and improve heat dissipation. The air flow absorbs the waste heat generated and transports it away from the housing area.
Control and regulation
ebm-papst offers intelligent EC fans (electronically commutated) that can automatically adjust their speed to the temperature or load. This saves energy and ensures needs-based cooling - i.e. only as much as necessary.
Integration into the motor housing
In many cases, the fan is mounted on the rear of the motor so that it blows the cooling air along the longitudinal axis of the motor. The air then flows over the cooling fins and cools the stator, the housing and sometimes also the bearings.
Typical components from the ebm-papst portfolio
• Axiallüfter (z. B. Serie 6300 oder AxiBlade): Für direkten Luftstrom über Gehäuse oder Kühlkörper.
• Radial fans (e.g. RadiCal series): For applications with high counterpressure or installation in cooling ducts.
• EC fans with PWM/Modbus control: Enable temperature control, speed control, diagnostic data, and much more.
Advantages of using ebm-papst fans
• High energy efficiency thanks to EC technology.
• Compact design, ideal for tight installation spaces.
• Durability and reliability thanks to high-quality bearings and materials.
• Low-noise operation, which is important in medical technology or electric vehicles, for example.
• Smart Control: Fans can be controlled via temperature sensors or external controls.
We will be happy to answer any questions you may have and look forward to hearing from you.
You can reach us Monday to Thursday from 8 a.m. to 5 p.m. and Friday from 8 a.m. to 2 p.m.