230v or 460v?

Denny Graham · Dec 5, 2014

Picked up a 2hp variable speed Bridgeport mill a while back. Don't know whether it was
connected 230v or 460v when it came out of the manufacturing facility. The motor plate
clearly details the 3 phase wiring for each voltage consisting of 9 wires.
The juncton box on the motor only has three wires in it, 1,2 and 3 which on the plate
are the line connections for both voltages. So in other words, the voltage selection has
to be made side the motor----some where.
I can't find any way to access the inside of the motor, short of total disassembly of the
vari-speed unit and motor.
It has been suggested that I try it to see if the motor will start. My voltage source is a
2 hp Phase-a-matic rotary converter generating my 230v three phase.
Anyone ever have a need to rewire one of these with the US Electric Motor?

Denny Graham
Sandwich, IL

Mike C. · Dec 5, 2014

If they left any colored remnant ends on the wires, that may help. Supposed to be red/white/blue or black on 230v. 460 would be yellow, orange, and brown.

TDegenhart · Dec 5, 2014

Mike C. said:
If they left any colored remnant ends on the wires, that may help. Supposed to be red/white/blue or black on 230v. 460 would be yellow, orange, and brown.

Don't depend on those color codes in the US. More than likely the wiring will be black regardless of the voltage.

Tom

motion guru · Dec 5, 2014

Measure the Resistance between phases and note the current ratings at each of the voltages -

Typical dual voltage 2HP motor would be:

(depends on efficiency)

230VAC, ~5.6A, ~2.5 - 3.5 Ohms
460VAC, ~2.8A, ~5.0 - 7.0 Ohms

Mike C. · Dec 5, 2014

Tom, if it were black, then it wouldn't be colored... would it? May also be phased taped with the proper colors. I always tried to phase tape or use colored wire on anything I dealt with for this exact reason.

TDegenhart · Dec 5, 2014

Mike C. said:
Tom, if it were black, then it wouldn't be colored... would it? May also be phased taped with the proper colors. I always tried to phase tape or use colored wire on anything I dealt with for this exact reason.

Last time I looked, black was a color. I have seen a lot of wiring to motors and except for internal wiring on a machine from off shore, I haven't run into these codes. Individuals may have their own standards such as yours, but I know of no other codes like this.

Tom

Denny Graham · Dec 6, 2014

Missing the point guys, I know the color code's and have followed them thru from
the 3 phase converter up to the reversing drum switch when wiring the machine.
This is a standard NEMA 9 wire dual voltage WYE connection and 1,2 and 3 are the
line in both hi and lo voltage modes. Those are present in the junction box and are
connected to the switch. Those are the only wires that are in the junction box and
none of the other 6 wires are visible.
Question is how do I access the other six wires to check or change the voltage?
The only thing that I've been able to figure out is that the cast iron fan has to
be pulled and the end frame pulled off, and that's what I'm not sure of. Seems
rather odd to expect the electrician to carry pullers in his bag and that he needs
to disassemble the motor to change the voltage wiring.
Can't seem to find anyone that has changed the wiring on a Bridgeport 2hp variable
speed mill using a US Motor, which was a division of Emerson Electric.

DG

Thomas Paine · Dec 6, 2014

probably was rewound on the cheap, and converted from dual voltage to single to save a couple of bucks.

Denny Graham · Dec 6, 2014

Now that's the first time that thought has come across the table Thomas. But it's a valid one and one that I hope isn't true. But it is possible that the motor was rewound at some point.
I'm gonna look into a resistance test as suggested and see what comes of it. Don't think I can come up with the exact resistance in a calculation because I'm sure inductance enters into the formula for the winding's at some point and the amperage is no doubt and an actual measured value with the motor running. I can see variation in the resistance calculations between the 220v-230v and the 440v-460v nominal voltages and the rated current draw, so I'm not sure just what the static resistance should be.
Just gotta get some heat up in the barn before I venture out there to play.
Thanks for the ideas.
Denny G

JST · Dec 6, 2014

The junction box WILL have the ends needed for all the wires present as winding terminations. If you have three, you have a single voltage motor, effectively.

It clearly must have been re-wound, if the plate says one thing and the wires are different. The motor is sufficiently special to justify re-winding at some point.

Now, you CAN go digging to see if you can locate and pull out wires for separate coils, but there is no guarantee you can find splices etc in appropriate places. You will end up second-guessing the rewinders.

Or maybe you can just find a suitable standard motor on some junked head that has other problems unrelated to the motor. It's not like a B-port is a rare machine. There are parts available used.

peterh5322 · Dec 6, 2014

"Now that's the first time that thought has come across the table Thomas."

Monarch Machine Tool, in an effort to save space, traditionally deleted the motor's connection box and directly wired the motor through three wires.

You remove the end-bell and then disconnect the three wires after labeling these T1, T2 and T3, and then you go looking for the other six.

Monarch's manuals for certain models state that "voltage conversions are not possible".

This is intentional, as:

1) the motor would have to be partially disassembled in order to get to the other wires, and

2) the NEMA reversing magnetic motor starter would likely be one NEMA Size too small on a 460 to 230 conversion, or possibly one NEMA Size too large on a 230 to 460 conversion. In any case, the starter's overloads would have to be changed [ * ] .

Yet, the schematic diagram which is supplied with the machine details how to rewire the spindle load indicator for all possible combinations from 5 to 20 HP and from 230 to 460 volts.

[ * ] Incidentally, an H-A-S-type conversion is possible, and while the motor is disassembled, anyway, it might as well be converted to 12 wires.

Denny Graham · Dec 6, 2014

Woah there Pete, H-A-S, NEMA magnetic starters, starter overloads-----ya'll got me buried in details. From what I can see,
this machine was hooked up to 440v with a pig tail and 20 amp twist lock plug off the Allen-Bradly reversing drum switch.
I've just got it plugged into a 20 amp four wire receptacle next to the phase converter. The drum switch will reverse two
of the legs, reversing the rotation.
For the time being, the only thing that I really need to know is how to get the plastic fan off without destroying it so I can
find the other 6 wires. Once I get over that hump then I'll concern my self with current draw and the need for magnetic starters.
Been running my 1hp 220v single phase 'J' head just plugged into the wall for 27 years now and haven't burned up the switch yet
and I'm reversing it for tapping all the time.
Denny Graham
Sandwich, IL

atomarc · Dec 6, 2014

It will be interesting to see what develops when you get into that motor.

I've been messing with those things for 35 years and have never seen a rewind shop hide unused motor leads up inside a stator. When a motor was rewound and clipped, the unused leads were wrapped with the rest of the winding, the stator was dipped and cooked and that was that. If a person down the line wanted that motor reconnected for a different voltage, he took it to a motor shop where the rewinder disassembled it, found the leads, pulled them out and re-dipped the stator.

Having said all that...and knowing your past history on another forum, I would bet you will pull this off with no problem at all.

Stuart

Denny Graham · Dec 7, 2014

I was gonna shelve it for a while Stuart, but---- being the bull headed Irishman that I am,
it's got my curiosity up as to what the problem is and as you can see, I won't be able
to sleep till it's solved.
I'm hoping that someone just poked the other 6 wires back into the space between the
housing and stator. Just need to figure out how to get the dang plastic fan off without
breaking it.
dg

Denny Graham · Dec 7, 2014

Well the exploratory surgery is complete and the results for the patient are not good.
The motor apparently has been rewound for single voltage at some point, and it’s not
220 voltage.

US Motor cooling fan removal:
2hp US Motor Fan 03.JPG photo - dennygraham photos at pbase.com

220v/440v dual voltage motor sadly rewired for hi voltage only:
2hp US Motor Stator Wiring 02.JPG photo - dennygraham photos at pbase.com

Next logical step for this motor is the industrial motor repair shop
next week to see what the experts have to say can be done with it.
Thanks for the help, on to the next project.

dg

peterh5322 · Dec 7, 2014

"Woah there Pete, H-A-S, NEMA magnetic starters, starter overloads-----ya'll got me buried in details."

Unintended consequences ... I apologize.

Denny Graham · Dec 7, 2014

No problem here Pete, just that this is a mill that's out in my barn that I'll use
a few times a month. On 220v 3ph. it's only gonna draw about 6 amps, it's running
#12 wiring all the way up to the motor, the A-B reversing switch is a three
position 2hp drum switch and the supply is an RPC so that shouldn't be a problem.
Also I'm fusing the three legs with 15amp breakers. So I don't think I'll have any
problems by not using a contactor.
I understand that in a commercial setting there would need to be much more
involved in the hookup and one could invest a grand just in controls. But I've
managed to climb up on step ladders without wearing safety harnesses and
god forgive me, but I've even depended on conduct as a ground between
boxes at times.
Denny G

Denny Graham · Dec 18, 2014

Finally heard back from the motor repair. They managed to bring out the other 6 leads from
the coil, which means that they won't have to rewind the motor. Hopefully I'll get the motor
back next week and it should be a lot less than a rewind.
With a little luck I'll be able to test how it's gonna be with the 2hp RPC, got my fingers crossed.

DG

230v or 460v?

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