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GE service centers are expert at assessing when repair is practical, removing the old bars and installing new bars. Determining the appropriate alloy for replacement bars is also critical, because any change in the conductivity of the rotor bars can drastically affect the speed-torque characteristics of the motor. Our knowledge of rotor design and proper repair procedures means a fast return to service for your motor and reduced downtime in the future. Rotor Failure CausesGenerally, rotor failures occur due to two major factors:
Excessive heat can result from operation on continuous overload, motor stall and too many starts in succession without adequate cool down, combined with excessive accelerating time. Melted or broken bars can confirm a failure from excessive heat. Breaks in the bar can occur in the slot section or at the end ring and are generally the result of differential expansion of the assembly with temperature. (Note that most materials lose strength with increase in temperature). Mechanical stress failures are generally due to repetitive centrifugal loading on the bar extensions or bar vibration. If a motor is subjected to frequent starts, the forces generated in the rotor can cause bar fatigue failures, especially if high temperature is present. Bar failure can also occur when the bars are loose in their slots, allowing them to vibrate. This situation happens most frequently on starting and during motor acceleration. For More InformationFor a detailed service description, click the following link: Find a service center that performs Motor services Related InformationRequest a quote |