More Bridgeport mill help needed

On 6/5/2011 5:35 PM, Steve Walker wrote:

by all appearances, a 3 phase motor, probably wired for 440 if memory serves

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Steve Walker wrote:

It looks like your maintance man is right.  You can run that motor on
either 220 or 440 but 3 Ø only.

John

john wrote:

The three wires 1,2, 3   are your power wires to the motor connected for
480. For 220vac  you would tie   1&7.  2&8     3&9  together and these
would be your power into the motor.   Wires 4,5, and 6 would be tied
together.

I am not sure how the contactor is wired into the circuit but there
should be either a control transformer on the machine that would have to
be switched to 220 from 480 or the coil on the contactor has to be
replaced.  IF you have a 110 volt outlet they might be using that for
the power for the contactor coil.  The transformer may  have jumpers or
taps to change the input voltage to 220.    The taps on a control
transformer are usually labeled  H1, H2, H3 and H4.  Each transformer is
different as to how they change the taps on the input voltage so you
should look closely at the transformer and see if there are any
instructions or diagrams on it.

John

Steve Walker wrote:


That wiring is just right for 440, 3-phase.
To convert to 240 3-phase, connect 4, 5 and 6 together and tape up.
Connect the mains to 1&7, 2&8 and 3&9.

It would be EXTREMELY rare to find an original Bridgeport spindle motor that
was single phase.

Jon

On 6/5/2011 23:22, Jon Elson wrote:

I thought so too, but the motor plate tells the tale.

https://sites.google.com/site/millwiring/pictures

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Steve Walker
Fusion640@frontierbrain.com (remove brain when replying)

Steve Walker wrote:

That plate certainly *said* 3 PH and may still say 3 PH. That also is
not an original data plate.

On 6/6/2011 21:25, Pete C. wrote:

Could you tell me the reason for the 115/230 designation (where the 115
is stamped over). I was unaware 115 volts came in 3 phase. Also, how can
I tell it's not an original data plate? Obviously it has been restamped,
and do you have a link to a picture of an unmolested data plate, so I
can see what has been wiped off over the years.

--
Steve Walker
Fusion640@frontierbrain.com (remove brain when replying)

Steve Walker wrote:

that

My thoughts on the 115/230 designation is that the data plate was reused
from some other motor and restamped.

A couple original motor data plates on Bridgeports:

http://wpnet.us/40s_bridgeport_motor.jpg

http://wpnet.us/70s_bridgeport_motor.jpg

    [ ... ]


    Except that the nameplates on Bridgeport motors are normally
anodized plates with clear places for stamping the data which may
change, such as voltage.

    What I suspect is that someone had the motor rewound to single
phase at one time, and pulled the drive screws and flipped the plate
over and stamped new information (including the Bridgeport name) into
it.  If you pull the drive screws (use dikes to get under the heads),
and look at the other side, I suspect that you will find the original
nameplate.  Later, someone re-wound it as three phase again.  I think
that I can see some reversed letters from the original stamping on the
other side.

    Or -- it *could* have been a third-party motor (or third-party
modification to the existing motor), which would again explain why the
"Bridgeport" name had to be stamped into the nameplate, instead of
etched into it as is normal.

    Anyway -- what you *currently* have is a three phase motor wired
for 460 or 480 VAC, no matter its history.

    Re-wire as I showed for the lower voltage 230/240 VAC and double
the current of the thermal fuses in the starter (assuming that you are
not going to be driving it from a VFD.  If you are -- the starter is not
really needed.

    Good Luck,
        DoN.

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    Common way to do this (though numbering schemes may vary, and
what I will ASCII draw here is based on your numbers as connected.

    Be sure to use a fixed-pitch font like Courier in your
newsreader to avoid distortion of the image (a common problem with
proportional pitch fonts):

                   7   4                1
+-----WWWWWWWWWW-----+-----WWWWWWWWWW-----+ (L1)
|
|                  8   5                2
+-----WWWWWWWWWW-----+-----WWWWWWWWWW-----+ (L2)
|
|                  9   6                3
+-----WWWWWWWWWW-----+-----WWWWWWWWWW-----+ (L3)

    The "WWWWWWWWWW" represents a specific winding in the motor.

    This is wired for the higher-voltage possibility.  
Now to re-wire as the lower voltage possibility:
                   7
+-----WWWWWWWWWW-----+--+--- (L1)
|                       |
|  +-----WWWWWWWWWW-----+
|  | 4                1
|  |               8
+-----WWWWWWWWWW-----+--+--- (L2)
|  |                    |
|  +-----WWWWWWWWWW-----+
|  | 5                2
|  |               9
+-----WWWWWWWWWW-----+--+--- (L3)
   |                    |
   +-----WWWWWWWWWW-----+
     6                3

Or -- in text, 4, 5, and 6 are tied together and insulated with tape.
               1 and 7 are tied together and make one phase (L1)
               2 and 8 are tied together and make another phase (L2)
               3 and 9 are tied together and make the last phase (L3)

    Whichever way it is wired (high voltage or low voltage), you
reverse it by interchanging any two of the three AC line feeds. (E.G
(L1) and (L2) -- or either of those and (L3) -- not not all three moved
at once, which will leave it running the same direction that it was. :-)

    Note that the other end of windings 7, 8, and 9 are tied
together inside the motor, just as you are tying together the 4, 5, and
6 wires when you are adding the second windings in series with the
first.  You could call the joined ends of the 7, 8, and 9 windings "10"
if you wanted to -- but since you can't get at it, don't bother to name
it. :-)

    Typically, for a reasonable sized milling machine, the high
voltage wiring pattern will be for 480 V and the low voltage pattern
will be for 240 V.

    Good Luck,
        DoN.

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