2 phase bridgeport motor tesla can you hear me?

jaros44sr · Oct 19, 2016

ok, did a search and no answers...

back round
Just bought a bridge port with a rotary phase convertor. Don't like the size and noise, trying to go down a different path...VFD or replace motor with an OEM 3 phase motor, since their are no 2 phase VFD's
serial# 16310

H&W make a conversion to a baldor replacement, but I like OEM if possible.

any help
Mods feel free to move, if I am in the wrong forum

bloomautomatic · Oct 19, 2016

I'm not sure what you mean by a 2 phase motor, but if you need to run a 3 phase motor off of a single phase input, there are VFD's that can do that. Up to 1hp you can use 110V, above that you need 220v.

If your motor is 1.5hp, I'd use the 2hp version.
https://www.automationdirect.com/ad...5_-z-_230_-z-_460_-z-_575_VAC_V-z-Hz_Control)

This is the best answer I can give based on the wording in your original post.

TDegenhart · Oct 19, 2016

What you are saying makes no sense. If a rotary phase convertor came with the mill, you have a three phase motor already. Are you saying the motor makes too much noise, or the convertor? 2 phase? Where did that come from? If it is noise from the convertor, build a sound box with insulation. Or spend $200 for a VFD. You may want the VFD anyway, as it offers features the rotary cannot do, mainly speed control. If you have the old belt changer, this is a nice feature.

Tom

rons · Oct 19, 2016

jaros44sr said:
Don't like the size and noise

The noise coming from the idler would indicate a crying out out for new grease in the bearings. You could also attempt to statically balance the rotor. All of this can be done in a garage.

Ziggy2 · Oct 19, 2016

The OP might actually have a true 2phase motor. This was a somewhat oddball configuration.

If this motor (2ph) is being powered from a rotary phase converter,then the converter is making the noise due to an improper phase shift between the motor and the converter, 120deg phase angle vs. 90deg phase angle. There is no good solution except to replace the motor.

JRIowa · Oct 19, 2016

Ziggy2 said:
The OP might actually have a true 2phase motor.

AFAIK, 99% of the double phase equipment was gone by the end of WWII. The only remaining systems are in Philadelphia. The only reason that I know that is from when I was in HVAC.

That said, I seriously doubt the OP has a double phase set-up and needs to read the motor plates.
JR

paracongo308 · Oct 19, 2016

More then likely that Bridgeport with the 2 phase motor came from the Philadelphia, Pa. area. The majority of you never heard of 2 phase, but if your a old person your grandfather might have ran machinery when it was 1st introduced. PECO electric still supplies 2 phase electric in the Philadelphia area. I remember running a Monarch lathe 40+ years ago that had a 2 phase motor. The company which was out of the 2 phase grid area used a transformer to run that lathe. If I recall 2 phase is 4 wires. To the OP, just replace your Bridgeport motor.

paracongo308 · Oct 19, 2016

JRIowa said:
AFAIK, 99% of the double phase equipment was gone by the end of WWII. The only remaining systems are in Philadelphia. The only reason that I know that is from when I was in HVAC.

That said, I seriously doubt the OP has a double phase set-up and needs to read the motor plates.
JR

About 13 years ago I was at a trade school auction close to the Willowgrove naval air station and they were selling a nice Bridgeport that I was interested in until someone mentioned it was 2 phase.

johansen · Oct 19, 2016

I would build a Scott T transformer.

I have suggested people do this to properly drive split phase capacitor run motors from a vfd, but never heard of anyone doing it.

In your case, you don't need voltage isolation so one of the transformers can be an auto transformer.

moonlight machine · Oct 19, 2016

paracongo308 said:
More then likely that Bridgeport with the 2 phase motor came from the Philadelphia, Pa. area. The majority of you never heard of 2 phase, but if your a old person your grandfather might have ran machinery when it was 1st introduced. PECO electric still supplies 2 phase electric in the Philadelphia area. I remember running a Monarch lathe 40+ years ago that had a 2 phase motor. The company which was out of the 2 phase grid area used a transformer to run that lathe. If I recall 2 phase is 4 wires. To the OP, just replace your Bridgeport motor.

A vintage car restoration shop I worked at on the north side of Trenton NJ in 1992 had 2 phase as well. Thats pretty close to Philly. 2 Phase...4 wire...strange.

apoc_101 · Oct 19, 2016

Replace it with 3 phase, two-phase is the devil.

paracongo308 · Oct 19, 2016

moonlight machine said:
A vintage car restoration shop I worked at on the north side of Trenton NJ in 1992 had 2 phase as well. Thats pretty close to Philly. 2 Phase...4 wire...strange.

The 2 phase service started in the 1890's in certain parts of the country. I knew a guy who had a automotive starter & generator repair rebuild shop in southwest philadelphia. He told me he had 2 phase service to his machinery.

jaros44sr · Oct 19, 2016

Thanks guys for posting up. seems the converter is making the noise, although I have held a screwdriver to the bearings and cannot detect any bearing noise. so that lends us to believe that there is a phase shift problem, which I wouldn't know how to solve, and as stated above, I could build a insulation box solving the noise problem in the converter.

also, suggested above, peco supplies 2 phase power, have to look into that. that would solve all my problems, since I can't find a 2 phase VFD. 2 phase seems to originate in the Rochester ny and philadephia areas, for whatever reason

but all that still leaves me with a space problem, although I could live with that until I find another solution, so, that leaves me with finding an OEM motor 1 hp in 3 phase or 1 phase, any idea where I could start to look for one

Modelman · Oct 20, 2016

Did you ever determine if the RPC was built from a two phase motor? I've never heard of it being done, but can't see why motoring a two phase motor on single phase wouldn't generate the other TWO phases. However, if someone was trying to drive it off of a three phase converter, I could see they being problems.

Dennis

M.B. Naegle · Oct 21, 2016

A suprising number of "electricians" don't understand 3 phase power. Ive talked to guys over the phone who swore they had 3 phase service when in fact they had single phase 220 with a neutral and a ground. That said with 2 phase being even more of an oddball power source, I think its highly likely whoever hooked this mill up thought it was 3 phase.

rons · Oct 21, 2016

jaros44sr said:
but all that still leaves me with a space problem, although I could live with that until I find another solution, so, that leaves me with finding an OEM motor 1 hp in 3 phase or 1 phase, any idea where I could start to look for one

New or used? Do you have any previous experience with how a RPC works?

1 hp in 3 phase: for the RPC unit???

1 hp in 1 phase: for the mill motor???

jaros44sr · Oct 21, 2016

OK, after several weeks of searching and talking to people, I came up with a solution. It came from an old motor shop that I've dealt with for 30-40 years. Came on a whim, to just talk about 2 phase, asked if he could rebuild and rewind my motor to single phase... he said " NO", but he could rewind it to 3 phase, GREAT. Puts me in the ballpark, now I can buy a 3 phase VFD

Thanks for all your help guys, I'll let you know how it works out in the weeks to follow, as there is a 7 week leed time on the VFD, most of that is travel as it comes from Korea

Anyone want to buy a used rotary 2 phase converter? Philly area

apoc_101 · Oct 21, 2016

jaros44sr said:
OK, after several weeks of searching and talking to people, I came up with a solution. It came from an old motor shop that I've dealt with for 30-40 years. Came on a whim, to just talk about 2 phase, asked if he could rebuild and rewind my motor to single phase... he said " NO", but he could rewind it to 3 phase, GREAT.

I don't even want to know how the hell that is supposed to be possible. I'd buy a used 3phase motor from somebody.

the physical design of a 2-phase motor, converted to 3 phase operation, is going to see a loss of torque and overall power output. I'd suspect losses in efficiency and a limited lifespan for the rebuilt motor as well. hope you don't need that power you're losing...

rons · Oct 21, 2016

jaros44sr said:
but he could rewind it to 3 phase, GREAT. Puts me in the ballpark, now I can buy a 3 phase VFD

If you go for that then ask him if you can watch. Offer to buy a sandwich at lunch.

johansen · Oct 21, 2016

apoc_101 said:
I don't even want to know how the hell that is supposed to be possible. I'd buy a used 3phase motor from somebody.

the physical design of a 2-phase motor, converted to 3 phase operation, is going to see a loss of torque and overall power output. I'd suspect losses in efficiency and a limited lifespan for the rebuilt motor as well. hope you don't need that power you're losing...

no, if its properly rewound you could get something like an additional ~10% hp from the motor switching from 2 phase to 3 phase (this is due to the reduced torque ripple) . and if its properly rewound by hand you should be able to fit a half or a full gauge larger copper wire in than it originally had, so further hp gains can be had.

additional phases after 3 quickly reach diminishing returns though allegedly some of the electric motors used to drive submarines have 7 phases.. to get effectively Zero torque ripple.

btw, with a suitable capacitor his 2 phase motor can run from single phase. at perhaps 2/3rds or less of its intended hp.

2 phase bridgeport motor tesla can you hear me?

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