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99 Posts
Four things spring to mind.
1. Loose connection on the DC side of the controller(s) can cause the current sensor to screw up under heavy load causing "surges" as controller thinks it is hitting its current limit even though it hasn't.
-Tighten all connection with a torque wrench to 85 INCH-pounds ( thats only 7 foot-pounds )
watch the terminals to make sure they do not rotate more than 5 degrees while tightening.
2. The current sensor is just bad, hook up a current meter to the dc side of the controller and compare the measurements between your meter and the one in the controller ( using a 1313 or 1314 )
3. Excessive gear lash on motor , if there is too much play in the drive system the motor can bounce back and forth in the gear lash...this can also cause premature failure of the motor encoder.
https://en.wikipedia.org/wiki/Backlash_(engineering)
4. Motor encoder is failing as high torque on motor shaft causes it to shift position slightly.
-If you have a 1313 or 1314 just watch the motor RPM and see if it jumps.
This is a difficult problem to definitively diagnose , it's usually done by process of elimination or just replace the thing.
So take care of #1 , it's something you should check once a year anyway.
Then check issue #2 , keep in mind that "Clamp on meters" aren't very accurate so if thats the type you're using don't expect the measurements to be exactly the same.
Then if the problem isn't found, check 3 and 4 , just remember that issue #3 usually causes issue #4.( the encoder is basically shaken to death and the gear lash causes the shaft to move more)
I hope this steers you in the right direction, good luck.
