• The winding shaft of an electrical motor may be damaged by improper lubrication.motor.jpg image by Aussiebloke from Fotolia.com
  
  Approximately 64 percent of all electrical equipment in the United States is driven by some form of an electrical motor. With proper maintenance, motors can last for over 30,000 hours of use, but internal stresses, improper usage and environmental factors may cause damage to vital parts, leading to motor failure.
  
  

Part Failures

• Bearing failure is responsible for over 50 percent of all motor failures, according to the Electrical Construction and Maintenance online magazine. It is usually caused by one or more of the following factors: improper lubrication, restricted ventilation, abnormally high temperature, excessive vibration and buildup of dirt and grime. The stator winding, shaft and rotor bar are also susceptible to failure due to internal stress.
  
  

Overload

• An overload occurs when the motor is made to draw more current than it was designed to accommodate, causing it to overheat. The high temperatures create additional stress on the motor's parts, shortening motor life. Overloads can be caused by malfunctioning equipment, a broken gear or frozen bearings.
  
  

Short Cycling

• Short cycling occurs when the motor is repeatedly turned off, then turned on again before it has fully cooled. This may cause the engine to overheat. The motor's manufacturer usually indicates the allowable range of cycles.
  
  

External Stressors

• Environmental factors such as excessive moisture, high temperatures, voltage disturbances and improper electrical connections can all cause major damage to motor parts.