Luther (Red) Norris 
Quality Solutions Co. LLC 
Greenwood, Indiana 
Technical Services Committee Member
 
Brushless servo motors are being used in industry for many different applications. However, the primary industrial use for these motors is in automated machinery for the accurate positioning of the work piece or work tool. 

The brushless servo motor will have many features that are different than the standard AC induction or brush type DC motor. Most service centers are familiar with the operation and characteristics of three-phase induction motors and with DC motors with a commutator and brushes. 

The brushless servo motor will usually have a stator winding similar to a three-phase stator with three power leads. It will have a rotor that, instead of an induction squirrel cage rotor or a wound armature, will have permanent magnets that match the number of poles in the stator windings. 

REVISED September 2022!

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Luther (Red) Norris 
Quality Solutions Co. LLC 
Greenwood, Indiana 
Technical Services Committee Member
 
Brushless servo motors ARE electric motors; therefore many of the tools needed to test them are already available in an electric motor service center. In this article, I have listed some instruments and tools that will be needed to service servo motors.

For the purpose of simplifying the instruments and tools needed for brushless servo motor repair, I am going to break them into two groups. 

• Group 1—those usually found in an electric motor service center.
• Group 2—those that may not usually be found in an electric motor service center. 

Tom May
Trade-Mark Industrial

For years, electric motor repair facilities have been routinely rewinding the common three-phase electric motor. I can recall the rare occasion where a winder slipped up taking a connection or counting turns, or missed recognizing a “specialty” two-speed or consequent pole connection. 

It happens. We have all experienced it and learned from it. Today, winders are facing new challenges when winding AC motors, particularly when it comes to spindle and servo motors. 

With the complexity of some of the newer technologies, the chance for error is significantly increased. We have had to become more observant and heighten our awareness. Here are a couple of examples that our service center recently encountered, and where we were able to identify the data and rewind the motor successfully.