According to Gary Wooding :
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?
You'll more readily find them on eBay, as the company is long
gone.
Well ... mine is a very old example of the toolroom version. A
choice of leadscrew and handwheel or lever for X-axis feed, while
leadscrew and handwheel only for Y-axis.
You might take a look at:
http://www.d-and-d.com/NICHOLS-mill/index.html
which will show you some of what I have done to and with it.
The weight is about 1100 pounds.
[ ... ]
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?
Not much -- compared to a single winding of the proper wire
gauge for the lower of the two voltages. You simply have two identical
windings of a smaller gauge, which take up a bit more room than a single
winding of the proper gauge, but when paralleled add up to the proper
gauge. And when connected in series (for higher voltage and lower
current), they don't need the additional current capacity, so they work
out correctly again. All of the wires are used all of the time -- just
in different configurations.
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.
Hmm ... nine terminals is standard for a two-voltage (but single
speed) US-made motor. But there is only one center point for the Wye
(star) connection. It looks something like this:
Primary Secondary
(1) (4) (7)
+---wwwwwwww---+ +---wwwwwwww---+ Phase A
|
| (2) (5) (8)
+---wwwwwwww---+ +---wwwwwwww---+ Phase B
|
| (3) (6) (9)
+---wwwwwwww---+ +---wwwwwwww---+ Phase C
^
|
+-- Wye center point
(not brought out)
Note that I may be mis-remembering the actual numbering of the
winding terminals, but the principle remains.
----------------------------------------------------------------------
Anyway -- (assuming a 240/480V version) for 240V operation, you
would connect terminals (4), (5), and (6) together, and insulate them.
Nothing brought out.
You would connect terminal (1) to terminal (7) and bring them
out to connect to the first phase.
You would connect terminal (2) to terminal (8) and bring them
out to connect to the second phase.
You would connect terminal (3) to terminal (9) and bring them
out to connect to the third phase.
----------------------------------------------------------------------
For 480V operation, you connect:
Terminal (1) to terminal (4) and insulate
Terminal (2) to terminal (5) and insulate
Terminal (3) to terminal (6) and insulate.
You connect terminal (7) to the first phase.
You connect terminal (8) to the second phase
You connect terminal (9) to the third phase.
----------------------------------------------------------------------
So -- you get operation at two voltages different by a factor of
two and use all of the windings in either configuration.
Delta connections are quite uncommon in machines of the size w
which I use in my home shop. I've never had to deal with the big
machines which were in the shop at work, including a planer which could
happily hold and plane down a 1-ton pickup truck, and have room left
over to work on a couple of Volkswagen beetles at the same time. :-)
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.
Because it was made for a single voltage only, while all that I
have seen have been designed for dual voltage at the least.
What is the ratio of voltages for a Wye-Delta conversion? I
should know that but I haven't had to use it, so I forget.
Granted -- three-speed motors are a totally different ballgame. :-)
Enjoy,
DoN.
--
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