Re: [CAD_CAM_EDM_DRO] Re: VFD drive problems with older 3-phase motors (corre...

In a message dated 12/25/2003 8:42:04 PM Eastern Standard Time,
pete@... writes:
Randy, this is not true. Perhaps you are getting confused by dual
voltage windings that use wye or delta connections? If two motors are
similar and one is wye wound and the other delta wound, the winding
measurements would be similar. Even if it was true that the wye wound
was twice the resistance of the delta wound, how could you tell which
you had without something to compare it to? Twice what resistance?
For Ted's issue it doesn't really matter. I just thought I would
point out that you really can't tell the winding configuration from
ohm-meter measurements.

Ted, I agree with you on the phasing. With 3 leads, you can't get it
wrong. All you can do is change the rotation direction. Have you
determined the way the motor was initially wired to the contactors to
confirm your theory of the winding configuration? Did you check all
of the VFD parameters and make sure they agree with the motor
specifications? The only problems I'm aware of regarding running
older motors from a VFD have to due with longevity. For example,
winding insulation breaking down, etc..

~petev
~Petev:

I was referring to motors with multiple winding configurations such as
multiple voltage motors. I must have missed his earlier post and may have
misunderstood the original problem. Sorry about that.

Randy Abernathy
4626 Old Stilesboro Road NW
Acworth, GA 30101, U.S.A.
Phone / Fax: 770-974-5295
Cell: 678-772-4113
E-mail: cnc002@...

I furnish technical support, repair, and other related services for your
industrial woodworking machinery. My background as Senior Service Engineer for the
SCMI Group for nearly fifteen years with factory training, combines with my
extensive background in electronics, mechanics, pneumatics, electrical and CNC
machinery to offer you needed support for your machinery.


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