I have a Sew-Eurodrive wa20 drs71m2/tf/es7c/v, 90 degree gearbox, driven by a powerflex 525 VFD that is running me in circles. It is chattering/ faulting out for over current in one direction only. Feels and looks for all the world like it is in some kind of a bind, except it never happens in the opposite direction. I swapped 2 phases on the motor, which reversed rotation as expected but also reversed the direction the fault occurs in. Opened the gear box, everything looks pristine (nice gear oil, no visible damage on gears, no axial play or lateral play, good oil levels). Previous shifts have replaced the VFD power module and the entire motor/gearbox assembly. The spare on there is not new, but seems weird to have the same issue. I am suspecting a parameter in the 525 (possibly DC injection used for braking??) may have been inadvertently changed, and if that sounds reasonable any direction on what I should be looking for in Studio 5000 would be appreciated.
Sew-Eurodrive motor/gearbox chattering in one direction only, Flex 525 VFD
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grizgrin -
January 4, 2023 at 5:06 AM -
Thread is Unresolved
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This is an industrial robotics forum, not a general automation forum.
You would be better looking for a general automation forum or best discussing your issue with Allen Bradley directly.
Not being Allen Bradley experienced, the following is a generalised statement based on opinion only.
You say you have also replaced the drive and gearbox and the same occurs.
- Could be a cabling issue, but I doubt it, but it's worth checking and confirming grounds etc.
DC injection braking is only used to bring the motor to a standstill during activation.
- Sending a controlled DC reference across 2 phases will lock the rotor.
- It is not used during motion commands - worth checking this is not being incorrectly used.
In most modern VFD's, they require to be commissioned to the motor rating plate to optimize the VFD.
They almost all include areas to enter or carry out a stator resistance measurement too.
In most cases where instability occurs it is because of these settings being incorrect.
There may also be settings that relate directly to gearbox parameters especially if the control of the VFD is not just a straight forward V/F proportional output where dead bands appear in the mechanical linkage and require to be smoothed using features of the VFD.
Certainly sounds like proper commissioning of the VFD problem to me.............
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Is there a vertical load that is being raised/lowered? If so then it would be a common scenario for it to fault out when lowering the load and not raising the load. Can you confirm if that is the case or tell us what the application is?
You may also want to ask your question on the PLC Talk forum http://www.plctalk.net/.
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what is the application? perhaps you can try removing motor and turning the gear by hand. if turning in one direction is harder then you have the answer. normally this would happen with asymmetric load (like vertical application, lift or scissor lift) but it could be binding due misalignment, or defective counterbalance (if present).
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