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Need opinion from VFD experts

Need opinion from VFD experts

(OP)
I know, here are experts for VFD and my question is directed primarily to them.
It is about the motor Konecranes type MF06 fed through the Dynamove Vector 3.



Motor winding should be as usual at first glance .
It is a simple , single-layer, three-phase, 4 pole winding (24 slots), connected in Wye.
But, technician from the rewind shop claims that the "start" and "end" of one phase are shifted to each other, as well as such a motor works well via Dynamove Vector 3.
Is that possible, since the shift between the phase windings in this case is not 120 el. degrees (see the pic below).


I think, it is very likely that this error was done in rewind shop and probably corrected by someone in site.
What is your opinion?

ACW Winding Design

RE: Need opinion from VFD experts

As I read your post I understand that the motor does run or did run.
I would be inclined to recheck the winding connection with DC and a compass.
There may have been something that mislead the tech. Your best judgement here.
Something to think about.
With the winding reversed, the back EMF generated in the reversed winding will also be reversed.
The effect on the motor may not be as severe as a quick look at the vector diagram may suggest.
We may have less than full load torque at FLA.
We may have increased torque ripple at full load.
I saw several three phase welding machines connected to two phases and the neutral instead of to three phases.
I was surprised that the cooling fans had not failed.
The welding current being used was low compared to the maximum rating of the machines and the rectifier circuit was surviving.
This was not my responsibility. I mentioned it and the response was;
"It works. What's wrong?"
I walked away and carried on with my billable work.
The point is that improper connections at some times and in special cases may not be as immediately destructive as we may expect.
If anyone else had posted this I would be waiting to see your response zlatkodo.
This is an interesting problem.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Need opinion from VFD experts

(OP)
Some similar information arrived from the other side of the world.
This time it's about a three-phase motor VCC 24V AC3X1648A (unknown manufacturer), 100 Hz, 2850 rpm , 4 pole , connected in a delta.
Again, the "start" and the "end" of one phase winding are replaced with each other. Motor was working with such a connection, for 3 years via some VFD.
Any comment is welcome.

Winding Design and Motor Repair

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