Lenze Servo Motor and Resolver Problems

Sometimes the manufacturer of a servo motor will use a different encoder (resolver)on a particular motor. I have had to re-wire the encoder to different pins on a connector in order to correct to the old system.

The controller is looking for feedback pulses from the encoder (resolver) to determine the attained speed. It sounds like the acceleration is fairly high which is not unusual for maximizing performance of a servo based system. When the controller, however, gets only part of its signals it may misinterpret the speed. Unfortunately, not all controller manufacturers design their devices to detect an unusual response to a given program.

Check the pin out of your new motor resolver against the pin out of the old one. They must match or you may encounter the exact kind of problem you describe. Also check that the resolvers have the same number of pulses per revolution. If you need to refresh your memory on resolvers, try searching the internet on "encoders".

We have lenze async motors in our plant with the resolver attached we have also exsperenced the same problem with starting the motor up and it taking off we found it was a feedback error from the motor to the resolver. motor was trying to go 1 way and resovler was counting oposite causing the motor to race to match positions. this was causing the motor to ramp quickly. we found that we had to do a motor reference to set the zero position on the motor. hope this helps

Is it possable to disconnect the brake and move the arm manually? if so you could check the resover position through its axis. Also check the zero positions and that the resolver coupling is not slipping

Is it possable to disconnect the brake and move the arm manually? if so you could check the resover position through its axis. Also check the zero positions and that the resolver coupling is not slipping

When you say "exactly the same spec," does it have the same number of poles (e.g. does it run at the same RPM at a given frequency)? Does the new motor have its own resolver, and is it the same as the old one?

Hi Bill

The motor is the exact same type motor issued from lenze exactly the same, so it should have been a simple swopt like for like out of the stores, as for the resolver its built in to the motor so is sold as one unit.

Interestingly I found a second same type motor today and fitted it with no further problems, which Leeds me to believe its definitely the resolver at fault.

Sounds like you're right -- resolver problem . . .

No feedback certainly could result in the controller trying to make it run (at 100%, in your case), depending on the design (apparently theirs), and it gives you an opportunity to make a suggestion to the manufacturer to make such a problem not occur.

thanks guys

Sounds like the problem is "resolved"! Sorry, I couldn't resist!

Give this link a try.

http://www.ctiautomation.net/Lenze-Servo-Motors.htm