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Application Notes:
Inspecting Electric Motors |
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Electric motors are the backbone of industry. The U.S. Department of Energy estimates that in the U.S. alone there are 40 million motors operating in industry, and the fact that those motors use 70 % of the electricity consumed by industry indicates their importance. |
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A program to avert costly failures in your facility will benefit from including thermal imaging as a condition-monitoring technique for electric motors. Using a handheld thermal imager, you can capture infrared temperature measurements of a motor's temperature profile as a two-dimensional image.
Thermal images of electric motors reveal their operating conditions as reflected by their surfact temperature. Such condition monitoring is important as a way to avert many unexpected motor malfunctions in systems that are critical to manufacturing, commercial and institutional processes.
What to check?Ideally, you should check motors when they are running under normal operating conditions. Unlike an infrared thermometer that only captures temperature at a single point, a thermal imager can capture temperatures at thousands of points at once, for all of the critical components: the motor, shaft coupling, motor and shaft bearings, and the gearbox.
What to look for?All motors should list the normal operating temperature on the nameplate. While the infrared camera can not see the inside of the motor, the exterior surface temperature is an indicator of the internal temperature. As the motor gets hotter inside, it also gets hotter outside.
What represents a "red alert?"Equipment conditions that pose a safety risk should take the highest repair priority. After that, consider that each motor has a maximum operating temperature that usually appears on its nameplate and represents the maximum allowable rise in temperature of the motor above ambient. (Most motors are designed to operate in ambient temperatures that do not exceed 40 C.)
What's the potential cost of failure?For a specific motor, you could do an analysis based on the cost of the motor, the average amount of time a line is down from a motor failure, the labor required to change out a motor, etc.
Follow-up actionsIf you suspect overheating is the result of one of the following, consider the action described:
- Inadequate airflow.
- Unbalanced voltage or an overload.
- Impending bearing failure.
- Insulation failure.
- Shaft misalignment.
Whenever you discover a problem using a thermal imager, use the associated software...
Click here to download the full pdf: Inspecting electric motors » | |
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