AB Flex 70 VFD Error 5 Over Voltage

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tlowery643

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Question: We have a Allen Bradley Flex 70 VFD that went out. We replaced it with new one, we have all the same settings in it but we are having a problem with it getting Error 5 Regen. Over Voltage. We are getting it pretty regular when the train comes into the motors that drive the train into the station so it does get a regen surge back to the drive, but so do the others motors right there with it back to their respective drives. We have adjusted a on the decel time some but read this morning that it is trial and error so maybe its very critical and we are going to have to play with it awhile to find the perfect setting, any other ideas appreciated.
 
My guess is DC bus voltage is getting too high and causing the error. Do you have a braking resistor installed to dump excess energy into?
 
I'm with Kwired. It sounds like you made need a braking resistor if you can't stretch the decel out long enough to prevent the fault.
 
tlowery643 said:
... We are getting it pretty regular when the train comes into the motors that drive the train into the station so it does get a regen surge back to the drive, but so do the others motors right there with it back to their respective drives. ...
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So these are traction drive motors on a train, and you have multiple motors on the traction wheels, all on VFDs with dynamic braking? Are they all on a common DC bus so that they evenly share the braking load? If not, one drive is always going to try to do the whole job because there are always slight differences in traction, motor slip, resistance etc. That drive then attempts to absorb it all, until it hits its limits and stays there, then the rest of them will share the remainder. That "lead" drive has to run at it's limits all the time, until it trips or fails. Sounds like that might be what is happening, which points to a bad design from the outset if that's the case.

A better description of the ENTIRE system might be more helpful.
 
Jraef said:
So these are traction drive motors on a train, and you have multiple motors on the traction wheels, all on VFDs with dynamic braking? Are they all on a common DC bus so that they evenly share the braking load? If not, one drive is always going to try to do the whole job because there are always slight differences in traction, motor slip, resistance etc. That drive then attempts to absorb it all, until it hits its limits and stays there, then the rest of them will share the remainder. That "lead" drive has to run at it's limits all the time, until it trips or fails. Sounds like that might be what is happening, which points to a bad design from the outset if that's the case.

A better description of the ENTIRE system might be more helpful.
Click to expand...

The motors are on the track, not the train and the trains are coming into pinch wheels with motor driving one of the pinch wheels. been running fine for 10 years? Seems as though we have adjusted on the parameters today and have about solved the issue. Thanks for all the answers and seems like a great site to learn from and come to when having a problem.
 
tlowery643 said:
The motors are on the track, not the train and the trains are coming into pinch wheels with motor driving one of the pinch wheels. been running fine for 10 years? Seems as though we have adjusted on the parameters today and have about solved the issue. Thanks for all the answers and seems like a great site to learn from and come to when having a problem.
Click to expand...

If they ran fine for 10 years, you may need to be looking for what has failed that you compensated for when changing adjustments, could also be a mechanical failure and not an electrical problem.
 
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