Induction motors are the most common type of motors used in industrial applications. This article focuses specifically on the top 3 major causes of induction motor failure. Induction motors are powered by alternating current electricity. Typically, centrifugal pumps are powered by induction motors, yet there are countless applications in which induction motors can be found. Induction motors are efficient, inexpensive and very reliable – often times for many years. Induction motors can operate under very adverse conditions. However, induction motors are still susceptible to encountering critical problems resulting in failure. Many times, induction motors will fail due to being overloaded in some aspect, usually due to human mistakes to run a motor under conditions too intense for the motor to handle.
The first major cause of induction motor failure is due to excessively high temperatures. High temperatures can damage induction motors very quickly. “The basic ambient temperature rating point of most motors is 40°C”1, which is 104°F. Usually, motors can overheat often because of an electrical overload2. Electrical overload is “caused by excessive voltage supply or overwork by drawing more current”3, meaning that the motor will have to work harder than usual, and thus begin to overheat. Another factor to consider is when starting an induction motor: the most demanding task for an induction motor is to start. A great amount of heat can be generated if a motor is turned on and off several times within a short time span. Thus, it is advised to avoid turning an induction motor on and off only when necessary, not for troubleshooting. As for what defines motors as “overheating” varies, thus it is best to consult the user manual to determine when a motor is running too hot.
The second major cause for why induction motors can fail (and may overheat, as well) can be due to contamination issues, such as dust, water, debris, and dirt within the motor. Over time, contamination can affect the motor’s ability to disperse heat. Contamination in oil can also damage the sleeve bearing, also known as a “wiped sleeve bearing”. The easiest way to prevent contamination of motors, it is important to consider its location, for “motors and generators are often mounted in a location that makes them susceptible to contamination”4
The third and final major cause for induction motor failures is due to bearing failures. Sometimes, bearing failures can thoroughly damage a rotor, resulting in a need to replace the rotor. Still, most of the errors resulting in a bearing failure are due to contamination. “The main factors behind bearing faults are dust and corrosion…Contamination and corrosion frequently accelerate bearing failures because of the harsh environments present in most industrial settings.”5 Although less frequent, improper alignment between the shaft and bearing can also damage the bearing, leading to a motor’s premature failure. Improper alignment, however, is more of an issue of the shaft itself and less of a motor issue.
Generally, the most common causes of motor failure are due to overheating, contamination and bearing failures. Yet to simplify further, the two main causes of motor failure are due to overheating and contamination. This is because contamination can lead to other failures within a motor, if not being the sole reason why a motor fails. Therefore, the most important factors to consider to prevent these issues are relating to the environment itself: a motor’s location and surroundings. Proper attention to detail, installation and care for an induction motor are efforts which humans can take in order to affect the reliability of an induction motor (and thus prevent these 3 major causes). What is more important to consider are a motor’s surroundings: for environmental contamination near a motor’s placement can greatly damage a motor over time. Induction motors are very reliable and their successes are due to human efforts, and failures attributed to human errors.
- Same as 2