DoN. Nichols wrote:


They sound like nice machines. Perhaps similar in capability to
my Nichols horizontal mill with the optional right-angle head to make it
also a vertical machine.

I tried Googling the Nichols but couldn't determine which one you have;
is there a model number or some other form of identification?
The table sizes of the Centec are 16"x4.25" for the 2A and 25"x5" for
the 2B, so although very sturdy machines they are not massive like
Bridgeports, and can be fitted into small workshops like the sheds that
are traditionally used by UK model engineers.


Of course -- industrial motors here are typically dual voltage,
but not accomplished by the Delta-Wye changeover but rather by having
two of each winding. For lower voltage operation, the second set are
connected to a common center point, and paralleled with the primary
windings. For higher voltage operation, the second set is split into
individual windings, and connected in series with the primary set, which
has its own common center point buried deep inside the motor -- not even
accessible through the termination box. This results in one voltage
being double the other -- e.g. 240V / 480V, rather than the somewhat
different ratio which you get from A Wye/Delta switchover -- which I
don't remember, because I never have to work with it.

Don't the dual windings increase the bulk of the motors? Another friend
has an old Holbrook lathe with a 3ph 2HP motor. It has 3 sets of
windings to give it 3 different speeds. Its massive: at least twice the
size of normal single speed motors - that's twice the linear size: eight
times the volume! He wants to convert it to run on 240v (via a VFD) but
the terminal block shows that its only wound in star format (9
terminals, 3 for each winding), so he needs to remove it from the lathe
and dismantle it to expose the star points. Trouble is, its built into
the cast iron base and appears to involve lifting the 2 ton lathe and
removing the motor from underneath - the motor must weigh around 200 Lbs.

Most modern 3ph motors over here have both ends of each winding exposed
in the terminal block, thus making it easy to configure into star or
delta format. Old motors like those in my Centec have the star point
buried inside the windings themselves, that's why I had to remove and
dismantle them in order to make the conversion.

--
Regards, Gary Wooding
(To reply by email, change feet to foot in my address)