Interesting Facts on Cooling Electric Motors

Overheating is a leading cause of electric motor malfunctions. A general rule of thumb states that the motor’s isolation system loses half of its life span when the temperature rises by 10°C. Similarly, the motor’s bearing phase loses half its life span when the temperature increases by an extra 15°C.

Therefore, you must implement efficient cooling methods to maintain your electric motor and ensure smooth operations. 

What Causes Overheating in Electric Motors?

· Poor Voltage Supply

An unbalanced voltage supply in your 3 HP single phase motor, or any other motor will lead to overheating. When the voltage is significantly high or low, the motor works harder to maintain its torque, which causes it to overheat. 

· Improper Ventilation

Ventilation is crucial because it facilitates cooling air circulation within and around the motor. When the vents are blocked, hot air will be entrapped inside the motor, leading to overheating. In addition, poor ventilation can lead to dirt accumulation, which affects the insulation system.

· Inadequate Work Environment

If your electric motor operates or is stored in a hot environment, it will overheat and eventually malfunction. Motors thrive in spaces that allow aeration and sufficient room for cooling.

· Improper Use

Like any other machine, your electric motor will come with clear specifications. Usually, some motors are designed to run consistently, whereas others work intermittently to avoid an overload or overheating. Therefore, your motor is bound to overheat if you don’t adhere to the specifications or detect signs of overheating.

Cooling Methods for an Electric Motor

The stator and rotor losses lead to heat generation, which circulates within the windings. Cooling methods are applied to ensure the heat exits the motor to minimize overheating. Below are three effective cooling methods.


Whether using the 3 HP motor, single phase motor, or any other AC motor, you’ll agree that fans are vital for the circulation of cooling air. However, their designs offer minimal baffling for airflow direction, and most rotate in only one direction. Unfortunately, that leaves out of your motor exposed to high temperatures.

Therefore, to ensure efficiency, you can increase the size of fans mounted on the rotor shaft. Alternatively, you can angle the fan blades in a strategic direction of rotation to ensure bi-directional operation. In fact, before installation, you must make sure the fans are bi-directional and made of durable materials, such as steel, heavy plastic, or aluminum.

Corrosion Detection

Corrosion in the rotor will block duct openings within the motor, limiting seamless airflow. Over time, the rust will limit the ferrous material, carrying magnetic flux within the rotor, causing the motor to break down due to overheating.

You should always check the motor’s inside and outside diameter to facilitate cooling for rust corrosion. Use an inspection light, mirror, or welding rod to probe for signs of blockage. These inspections should happen regularly.

Customising Your Ventilation

If you want the best cooling system, it’s fair that you customise it to your content. For example, most electric motor companies will design custom air baffles to reduce winding temperatures and mount a fiberglass shroud on your motor’s ribs. 

You can also design custom i-directional fans with adequate sizes to cover the motor’s interior. However, you must work with an experienced electric motor company like Godrej to meet all your specification needs.

Liquid Coolants

Although moisture can cause a malfunction, proper use of liquid coolants will aid in cooling the motor during operation. Generally, liquid coolants like glycol and water have a higher heat absorption capacity than ambient air. 

Therefore, you can use an open loop cooling system where the water from the primary source circulates the motor’s exterior during operation to absorb heat. Alternatively, you can use glycol or a non-water coolant in the closed loop system. Here, the coolant circulates through a heat exchanger to cool the motor. This coolant is reused for the entire process.

Cooling Ribs

You will install cooling ribs on the motor’s external frames to increase the surface area for extensive heat radiation. Here, the cooling ribs ensure the airflow is near the motor’s surface, which enhances cooling and cleanliness. Manufacturers also space the ribs, leaving an air gap to facilitate seamless aeration. 

Electric motors are integral to many processes, and a sudden breakdown can lead to significant losses. Therefore, always ensure proper airflow and cooling during operation and storage. Cooling will happen seamlessly when the motor is well-maintained, and the life span will be longer.

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