The two most common methods of motor testing

Regular testing of the electrical motors provides many benefits, including financial savings, energy conservation, improved safety and increased uptime.


Regular testing of the electrical motors provides many benefits, including financial savings, energy conservation, improved safety and increased uptime. Courtesy: CFE MediaThere are an estimated 300 million electric motors in operation worldwide. Plus, 30 million new electric motors are sold annually for industrial use. On average these motors account for almost 70% of the electrical consumption at most industrial facilities.

Regular testing of electrical motors provides many benefits to a business, such as financial savings, energy conservation, improved safety and increased uptime. The opposite is also true. Without proper testing and preventative maintenance, more costly repairs and downtime can be expected.

Various types of motor testing should be included in a routine maintenance program. The kind of testing depends on a variety of factors, including inspecting and testing the type and size of the motor. Other tests include vibration analysis, bearing inspection, infrared scanning and resistance testing. These tests can be broken into two categories: online and offline testing.

Offline testing

Offline testing, sometimes known as a motor circuit analysis, can be used on a regular basis to determine the functioning components within a motor. These components include the windings and the rotor bar. Also, offline testing should be used for current and voltage analysis.

Offline testing finds broken or loose rotor bars, rotor eccentricity, problems with the end rings and misalignment problems.

This type of testing is scheduled because, as the name suggests, the motor must be taken offline. Testing should be done after a failure or scheduled for a time that is most convenient for the operation of the facility.

Routine offline testing is still an important part of any maintenance program.

Online testing

Online testing, also known as dynamic testing, is performed while a motor is running and provides information about the power quality and the motor's operating condition.

Analyzed data collected during online testing can reveal potential problems. Different indicators can show the health of the motor, including the power condition, motor condition, motor performance, load assessment and operating efficiency.

When online testing is used as a routine part of a maintenance program, it helps reveal problems occurring within the equipment.

Using them together

The combination of both online and offline motor testing contributes to keeping things up and running. Working them into a routine maintenance program helps keep problems to a minimum. 

- David Manney is a marketing administrator at L&S Electric. This article originally appeared on L&S Electric Watts New Blog. L&S Electric is a CFE Media content partner.

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