Electric motors are used in machines and processes all around us. You can find them in factories, automobiles, airplanes, robots and even your favorite DVD vending machine. Regardless of the application, managing heat dissipation is a common theme. Electric motors are often selected based upon a particular work or load requirement. One consideration of this selection process is managing heat dissipation. Although electric motor design is constantly improving, all generate heat through losses and inefficiencies. This needs to be evaluated when selecting the proper motor for your needs.
In most cases, heat dissipation is achieved through conductive cooling. In this method heat is transferred from the motor through the mounting interface into the machine structure. Motor manufacturers will often note a heat sink size on their data sheets. This heat sink size is used to determine the continuous torque capability of the motor. If more or less heat dissipation is available, the motor's load capability is increased or decreased. The Kollmorgen AKM Servo Motor shown above uses conductive cooling.
Another method to remove heat from electric motors is by providing forced air cooling. This is commonly done by providing an electric fan to blow air over the motor. Force air cooling can reduce the amount of heat transferred into the machine structure and allow the motor to be operated at a higher load point. A foot mounted PMDC (permanent magnet direct current) motor with air over cooling (TEFC) is shown above.
Liquid cooling can also be used to dissipate heat from an electric motor. With liquid cooling ethylene glycol or other liquid cooling agent is circulated in or around the motor housing or coils to dissipate heat. This would be similar to the radiator system on an automobile engine. The motor above is a custom water cooled design by Kollmorgen.
Although heat dissipation is not always a top criteria for electric motor selection it should be considered as part of the overall machine build. Some motors can be located on a machine where excess heat could cause burns to users. Thermal expansion caused by heating of a machine structure could cause process issues and under sizing or ignoring motor heat dissipation could result in product failure.
Like any complex machine with multiple moving parts, electric motors are vulnerable to common performance issues like misalignment, bearing wear, and harmonic distortion. One of the most common performance issues in electric motors is overheating.
Experts suggest that an 18°F (10°C) degree increase in motor winding temperature can directly affect the insulation of the component and reduce its lifespan by 50%. This has an irreversible impact on the lifespan of your machinery, regardless of whether the overheating was temporary or long-lasting.
Because heat is the most significant enemy that electric motors face, the question becomes: how can you prevent overheating and minimize the cost of replacing or repairing your electric motor?
Protecting your motor begins with understanding the most likely causes of overheating.
Your electric motor is a complex machine and requires a careful balance of environmental and supportive factors to run smoothly. Overheating in an electric motor can happen for a variety of reasons.
The most common causes of overheating include:
Avoiding the issues associated with overheating requires the right equipment, careful planning, and preventative maintenance.
The first step any professional should take before buying an electric motor is to ensure they’re purchasing the right machine for the right application. Check that the size, voltage, and performance are all rated to suit your specific needs. If you aren’t sure about your requirements, you should speak to an expert.
Once you’ve chosen the right motor for your company, find the right home for it in your industrial space. Remember that where you place your motor will affect its chances of overheating. Keep it away from other sources of heat, give it plenty of space, and make sure that the ventilation holes are clear.
When you start using your electric motor, remember to consistently monitor its temperature and performance for signs of overheating or deterioration. If you have taken all potential issues into consideration and your machinery is still getting too hot, this could be a sign that there’s something wrong with the internal components. You should ask a professional to run a check up on your electric motor to get a clear answer.
By scheduling regular checkups and servicing from the team at Sloan Electric, you can help minimize the risk of your electric motor overheating.