Motor Overheating Caused by VFD

Many factories rely on automated devices.

In today's modern production facility, many machines are automated for production quality and timeliness. VFDs can control motors that provide movement to an automated machine, but overheating can be a factor that workers need to supervise.

Identification

A VFD, or Variable Frequency Drive, is a device that converts AC, or alternating current, to DC, or direct current. After converting the electrical input and attaching it to a motor, the drive allows workers to change the speed of the motor at will.

Considerations

Because of the VFDs ability to change the motor's speed to either faster or slower, motor overheating becomes an issue. A motor cannot run below its minimum rated speed since its shaft-attached fan cannot spin fast enough to provide the correct cooling.

Prevention/Solution

It is imperative that the worker in charge of a particular VFD understands the lowest speed that the attached motor can withstand. Without proper speed, the motor can have its overall lifespan reduced by damaging the bearings and internal insulation.

References

• Automation Direct: How to choose a general purpose motor vs. an inverter-duty motor