Re: [CAD_CAM_EDM_DRO] Re: VFD drive problems with older 3 phase motor? Working!

In a message dated 12/27/2003 9:29:48 AM Eastern Standard Time,
ted@... writes:
My remaining question - Robin suggested that I should rewire the motor
parallel instead of series. I don't quite understand this. If the
motor was meant to be run two-speed originally at 240v, then I would
think that there is a way of driving the windings using the standard
6-wires and getting full speed and power from the motor. This is
typically spec'd as using the 1-2-3 for 3-phase input and 4-5-6
shorted. If I rewire the windings in parallel, I would expect to get
more power and more current draw than the faceplate specifies in the
normal 2-speed configuration. This is fine, but I don't understand why
rewiring might be necessary to get full faceplate power from the
motor.

Thanks for your help.
-Ted
Ted:

It will depend on whether your motor was factory wound as a constant torque
or constant horspower configuration. If it was wound as a constant torque
motor then I don't think re-connecting the wires in a parallel configuration will
help you out except to pull more current. I am going to assume that to run
the motor in it's slow speed mode you merely disconnect the 4-5-6 wires and
apply power to the 1-2-3 wires. If this is the case, then don't attempt to wire
them in parallel as the motor is not designed to be connected in that manner.
If the name plate shows a single voltage but two speeds then you don't want to
try connecting 1-4, 2-5, 3-6, you will pull way too much current. Most
single voltage, two speed motors are six lead motors as yours appears to be, the
dual voltage two speed motors will usually have 12 leads or 9 leads.

I hope this helps.

Randy Abernathy
4626 Old Stilesboro Road
Acworth, GA 30101
Ph / Fax: 770-974-5295
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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