Opps, missed the 1930 partdid they have that technology in the 30's?
Doubtful that you could accomplish a monumental task like this.Right, but if I were to rewind the motor as though it were a single phase with a starting and running winding would it be possible?
So since there is relatively little load on the motor during starting could the motor start on just a running winding without the aid of a starting winding?Power is applied to the drive train via a knee operated clutch. Because of this the starting load is minimal, so a high stall torque motor is not required.
No. Even with absolutely no load a cap start motor will just sit there and buzz if the start circuit is not engaged. You can hand spin the rotor to start them though.So since there is relatively little load on the motor during starting could the motor start on just a running winding without the aid of a starting winding?
I can't reference this rosenberg book you have, but the link I posted in post#12 shows all the different types of single phase configurations with a condensed explanation of each. just pick the one that looks easiest for you. The previous statement is only because you seem dead-set on rewinding this motor. I still don't think it will work and I advise against it. If you do nothing else, at least record the # of turns each winding and the configuration so that a rewind shop will have something to work with in case your attempts fail. I would hate to see this old motor rendered permanently useless.I guess I just want to rewind a motor for the heck of it. I think it would be an interesting project. I might document it on my friend's blog.
I understand your point about not wanting to mess with a vintage machine, though I should add that the motor had already been rewired. The way I look at it, if I wasn't giving this motor new life, it would be in the scrap yard right now.
And just to clarify, I'll definitely need a starting winding, but is the start cap absolutely necessary? The Rosenberg book shows a split phase motor w/o a start cap with the starting winding controlled by centrifugal switch. My plan is to forgo the centrifugal switch and control the starting winding manually.
A magnificent mechanical marvel!As promised, a picture of the machine.
What do you mean by "reconnect"? Are you planning on just hooking up 120vac to 2 phases of the 3 phase motor; or are you talking about performing your custom singlephase configuration? If you are talking about the former; I can almost guarantee that won't work. I tried that before (on accident) with a 3phase 480V 5hp motor. When I hooked up the 2 phases (3rd phase wasn't connected on the other end) the motor just hummed. I was able to start it spinning by hand, but I was also able to stop it spinning by hand. NO TORQUE. This will also burn up a motor; referred to by electricians as "single phasing" a 3 phase motor. "what happened to the motor?" ... "it got single phased and burnt up."I think I'll just reconnect it to run on 120v and hand crank it to start on a single phase. If that works out OK I'll leave it be.
Rewinding a motor in the original way shouldn't hurt the historical value. If you found a motor that old which hadn't been rewound, I'd be leery of hooking electricity up to it. I just don't think you'll be able to find the data for how it's supposed to be configured so I recommended recording that before you modify it (just in case).The motor has already been rewired so I won't be hurting the historical value.
no worries I just hope I don't come across as a naysayer.Oh, and thanks for the offer strantor but I live in the Philadelphia area. If I decide to do that rewind down the road I'm sure I can pick up an old three phase to practice on for cheap. And thank you all for your patience and advice, I know it's not easy dealing with a n00b!
There are instructions in the Rosenberg text on how to reconnect the leads to the winding to reduce the voltage. I was under the impression that a three phase motor would run on one phase, but that it just wouldn't start on one phase, no?What do you mean by "reconnect"? Are you planning on just hooking up 120vac to 2 phases of the 3 phase motor; or are you talking about performing your custom singlephase configuration?.
You might find this Rotary Converter & Motor/Generator manufacturer information enlightening.I was under the impression that a three phase motor would run on one phase, but that it just wouldn't start on one phase, no?
Sounds to me like you're talking about wye/delta wiring. wye is usually used for low voltage (230V usually in my experience) and Delta (480V usually in my experience) This is only for motors where you can access both ends of all 3 windings. if they're connected up inside, you won't be able to change that. if it's rated at 230V then it's probably already hooked up for "low voltage"There are instructions in the Rosenberg text on how to reconnect the leads to the winding to reduce the voltage. I was under the impression that a three phase motor would run on one phase, but that it just wouldn't start on one phase, no?
I can't answer that with 100% certainty because I've never worked in a rewind shop, but I'm pretty sure they just take what you give them and redo it. I've always been told that before you do anything with motor windings, you should write it all down because the rewind shop doesn't have anything to go by if you don't. I know that it takes a lot of engineering to determine #of turns, air gap, HP, amp draw, wire gauge, insulation, speed, #poles, etc. I doubt the rewind shop employs an engineer to figure all this stuff out when someone's brought in a motor without windings or with wrong windings. They may or may not have templates of "what works" for different sized motors. I don't know. I do know that sometimes even when you bring the motor still intact they can screw it up and then the motor will run hot.I'm still interested in rewinding the motor as a single phase, but I have a few unanswered questions like what gauge wire to use, and the exact winding confirugation. I know it has to have 4 poles to spin at 1750rpm, but other than that I'm really in the dark. How does a winding shop figure out what configuration to use when an unwound motor comes in?