VFD problem.... 1

[mike1969]

I have a VFD, when we hook a motor to it the shaft just rocks back and forth; when the same motor is hooked up to the drive next to it it works fine... Why are the motor shafts just rocking back and forth on this drive and not running? I have tested the the diodes and transistors as well as the capacitors in the unit, where else do I need to look/test?

 

[jraef]

Sounds like the firing sequence is screwed up. Not much you can do about that besides replacing the main board (depending on the drive design). What size / mfr / model drive?

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[mike1969]

its an older magnetek e505 model (I think its a 505) we deal with a lot of Yaskawa now and I'm pretty sure they actually made these units under the magnetek name. I will be able to check the model tomorrow to be sure.

 

[jraef]

Magnetek, Saftronics, EMS, Electromotive, Omron, IDM, they were all different "brand label" partners for Yaskawa, the drives themselves were identical for the most part. Magnetek was the biggest of the bunch and Yaskawa moved into the US as their own entity by buying them and killing off all of the other agreements. You can still get parts from Yaskawa, but also less expensively from numerous 3rd party repair companies like Electrical South (themselves an ex-Yaskawa partner) and NyCo, places like that.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[mike1969]

that helps, but is there a way to test the firing sequence to verify this is the problem? If so, what would cause this problem?

 

[DickDV]

Sometimes you can get that kind of motor behavior when the drive is set up as sensorless vector but the motor ID run has not been made or is defective. If the drive can be configured as a V/Hz drive, see if it will run the motor properly in that mode.

 

[buller]

On some of the older Siemens (Relcon) drives we had to check the hidden sync parameter and bring it dowwn to about 50.

 

[mike1969]

Hidden sync? Where would I look for that in a magnetek drive...

 

[jraef]

Didn't have it. That was not germaine to your issue, Relcon drives are an ancient version of Siemens drives from Canada, no longer made or even supported.

The 505, as advanced as it was for its day, was not a vector drive. It was a very good, but very simple (by todays standards) V/Hz drive. There was no motor ID run to perform, heck it didn't even care if a motor was connected at all!

The shaking back and forth is indicative of a high DC content in the output wave form, meaning either one (or more) of the transistors is shorted or they are not being fired at the right time (or some not at all). If a transistor was shorted the display would be telling you that and/or a fuse would be clearing. So that leaves a mis-fire. This is a 15 year old drive and it's time to fix it or scrap it, this isn't a matter of programming.



"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[mike1969]

Jraef, you are absolutely right. The unit is 15 years old (outdated by most standards) the transistors and diodes both test good, it really is time to upgrade this unit (they got their moneys worth) and my question (s) have been for my own benefit. The more capable I am at troubleshooting the less they drive me crazy, I'm constantly trying to learn more to feed my need to keep up (somewhat) with technology. Any help is appreciated

 

[jraef]

Well you did fine in elimiating the power component possibilities, but honestly, board level trouble shooting is usually a waste of time now. The cost to find and then repair a board component, only to discover the next level of cascaded failure, is almost never worth the effort. My tactic now is to eliminate the easy or obvious possibilities, then replace the board if it wasn't one of those. Anything under 20HP now probably isn't really even worth that effort in most cases.

 

[itsmoked]

Amen to that.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ozmosis]

mike1969
did you try a factory reset on the drive? if in doubt and not sure what has been set, then this is often a way to get back to the start and run the motor with the basic drive settings. If this works, then it is likely a parameter incorrect (as DickDV indicates). If not, then it is kaput and as jreaf suggest, don't bother try to get it repaired if its 15yrs old.