Your servo drive pops an error code. You write down the error code and look it up in the manual – it corresponds to a “resolver overspeed” alarm. Next to that is written “check the feedback cables” as a probable solution. You replace the cable and get the same alarm.

How to Identify the Source of a Servo Motor Resolver

Overspeed Error

A servo motor resolver overspeed error is a very common alarm, and can have many causes. Many of these error or alarm causes are easy to fix. With a process of elimination you often can determine what part of your system needs repair.

Are Your Cables Properly Shielded?

Your cables should have an internal shield that is properly grounded. Shields are usually grounded directly to the inside of a cabinet. Resolver based systems are very sensitive to noise and can be prone to alarms if not properly shielded.

Has Your Servo Motor Been Disassembled?

Have you had your servo motor rebuilt, or tried to rebuilt it yourself? If so, was the resolver properly aligned to the motor? If for any reason your resolver has changed its position in relation to your servo motor your system will not run. A misaligned resolver can cause many alarms, including resolver overspeed.

Has Your Servo Resolver Wiring Been Changed?

If you have swapped drives or changed cables then your wires could have been connected incorrectly. Swapping resolver wires can cause the resolver to swap direction, change to location of the zero position, or not function at all. Miswired resolvers can cause overspeed alarms.

In Summary

These are some tips to remove a coupling from the shaft while minimizing possible damage to your servomotor.