Help catching my runaway TLY Servo

[JumpStreet 0]

Hi All,

I have an AB servo TLY-A110T and 2097-V31PR0-LM Kinetix 350 drive. I thought that it was fully configured and ready for tuning, but when I issue a MSO it immediately starts to spin the shaft (no load yet). This lasts about a second until a Physical Axis Fault, Excessive Velocity Error occurs. I've double and triple checked the feedback and power wiring, and everything looks right. Is there anything else I can check? What can I do to trouble shoot this if I can't even give an MSO?

Any insight is greatly appreciated.

[Joe E. 259]

I've only ever started up one Kinetix servo drive, and it was a 6500 driving an old Anorad linear motor, so this may not fully apply to your case. If you double-click on the axis under Motion Groups, the axis properties dialog box has a step for "Hookup Tests" that lets you check the rotation and feedback. You can also do the tuning from this dialog box. As I recall, this was before writing any ladder logic.

 

[Izzybe 13]

Jumpstreet, I have used the same setup. I have never encountered a run away problem.  The K350 and that particular servo has software overtravel limits that need to be disabled out of the box. 

Items to check out:

• Safety circuit works accordingly, we are dealing with motion here (STO signals...)
• PLC startup is: Load firmware into controller and drive...
• Load PLC code (make sure that your motion instructions are disabled for now -- you can put AFI's in the logic)
• Check under your PLC controller properties: Time/Date tab -- check box is marked "enable time synchronization" and I assume that your PLC system is the master - status light will be next to "is system time master" ---> if you are doing CIP motion - this is the first thing you check. 
• use the direction motion axis commands to check servo out (MSO, MAM,...) -- set drive parameters accordingly
• Tune at this point
• is the drive and servo behaving accordingly with motion direct commands
• double check logic (maybe you are doing a MSO, MAH, MAM, ... Execution combo that makes your servo run away)
• If not, start looking at your drive firmware what version you are currently at.

I hope this helps with motion.

Edited 14 Jun 2019 by Izzybe

[Izzybe 13]

for motion direct commands for servos - check this out:  https://onlineplcsupport.com/allen-bradley-servo-control-order-of-operation

 

[JumpStreet 0]

Well, unfortunately this was never fully resolved. Here is what we found: Deleting the axis and starting from scratch did seem to stop the runaway problem. However, after adding a new axis and autotuning, the unloaded shaft still (about 1/2 the time) would drift and correct itself. It would bounce back and forth through an angle of about 30deg. 

When I rotated the shaft by hand, it would easily allow me to rotate it, and it would "cog" every 40 or 50 deg and sometimes not servo back to its original position. 

However, this was not repeatable, and it often would servo. One behavior that was repeatable, was that if we commanded it to jog forward it would sort of jump or cog in 50-60deg intervals. This could be smoothed out by increasing the system damping in the Manual Tuning parameters. 

Rockwell tech support agreed that it was behaving like it was single phasing, or not commutating. 
We tried a new drive, and saw the same exact behavior. For now, we aren't going to replace the motor or cables, because it seems to be managed by increasing the system damping (for example increasing damping from 1.0 to 0.7). 

Thanks to everyone for your help.