A few months ago I picked up a 15 hp severe duty baldor motor that appears to be brand new from the scrap yard for a whopping $60
Don't ask me why I bought it .... let's just say it is hard to resist a bargain .
And please don't ask why I am thinking about building another phase converter when the 10 hp converter I have now more then meets my needs .
I don't have a good answer for that either except I don't know what else to do with this big heavy monster .... and it can't hurt to have a back up right ?
my plan is to build it as cheap as possible with a pony start and that brings up my first question.
If I direct couple my pony motor to the idler motor will I have to take the start and run capacitors on the pony out of the circuit to prevent drag on the idler once I turn the power to the pony off ?
And the next question. .
What if any alternative's are there to a magnetic contactor to prevent it from attempting to restart after a power loss ... I live out in the country so this is a must .
Rotory phase converter questions
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Magicniner
- Posts: 532
- Joined: Thu May 30, 2013 4:40 am
Re: Rotory phase converter questions
Can't you use one-way bearings between the starter shaft & pulley (aka sprag clutch) they even do them with internal and internal keyways for this kind of application 
Re: Rotory phase converter questions
Why use a pony motor? Capacitors are available from people who scrap HVAC equipment. Also contactors and relays. Keeps the moving parts count down.
Here's how to use them;
http://www.bing.com/search?q=capacitor+ ... sp=1&ghc=1
CZ
Here's how to use them;
http://www.bing.com/search?q=capacitor+ ... sp=1&ghc=1
CZ
Re: Rotory phase converter questions
I have a couple reasons to use a pony motor , first is I already have a suitable motor for the pony ... I'd have to buy more capacitors .
Second is with a pony motor I don't have the huge in-rush of current to start the idler.
My 10 hp generator already dims the lights when starting
But the biggest reason is I already have 95% of everything needed to build it with a pony versus self starting and with no immediate need except as a back up I don't feel the need to spend any money that isn't absolutely necessary.
The sprag is a good idea , I'll have to think on that a bit .
Second is with a pony motor I don't have the huge in-rush of current to start the idler.
My 10 hp generator already dims the lights when starting
But the biggest reason is I already have 95% of everything needed to build it with a pony versus self starting and with no immediate need except as a back up I don't feel the need to spend any money that isn't absolutely necessary.
The sprag is a good idea , I'll have to think on that a bit .
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John Hasler
- Posts: 1852
- Joined: Tue Dec 06, 2016 4:05 pm
- Location: Elmwood, Wisconsin
Re: Rotory phase converter questions
No. Disconnecting power from the pony does so (but as long as it has the same synchronous frequency as the converter motor and is direct-coupled to it you can leave it connected and running).stephenc wrote:A few months ago I picked up a 15 hp severe duty baldor motor that appears to be brand new from the scrap yard for a whopping $60
Don't ask me why I bought it .... let's just say it is hard to resist a bargain .
And please don't ask why I am thinking about building another phase converter when the 10 hp converter I have now more then meets my needs .
I don't have a good answer for that either except I don't know what else to do with this big heavy monster .... and it can't hurt to have a back up right ?
my plan is to build it as cheap as possible with a pony start and that brings up my first question.
If I direct couple my pony motor to the idler motor will I have to take the start and run capacitors on the pony out of the circuit to prevent drag on the idler once I turn the power to the pony off ?
No practical ones for that size machine.And the next question. .
What if any alternative's are there to a magnetic contactor to prevent it from attempting to restart after a power loss ... I live out in the country so this is a must .
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Rich_Carlstedt
- Posts: 1757
- Joined: Sat Dec 21, 2002 12:16 am
- Location: Green Bay Wisconsin USA
- Contact:
Re: Rotory phase converter questions
1. Pony start is good as it eliminates a huge inrush of current.stephenc wrote:...................................................
....... build it as cheap as possible with a pony start.....................
If I direct couple my pony motor to the idler motor will I have to take the start and run capacitors on the pony out of the circuit to prevent drag on the idler once I turn the power to the pony off ?.....................................................What if any alternative's are there to a magnetic contactor to prevent it from attempting to restart after a power loss ... I live out in the country so this is a must .
2. Why do you have start and run caps on the pony ? If it is 3 phase also, are you starting it with the 10 HP Converter or is it on it's own static convertor circuit ?
3. Once you kill power to the pony motor , it will not be a load on your rotary convertor as no power is flowing in its circuit, however you will have more noise and unnecessary wear on the pony motor. I would have a clutch arrangement, using a one way needle (as mentioned) or a V belt and pivoting pony motor.
4. Magnetic contactor is the only answer to your quest.
Rich
Re: Rotory phase converter questions
Practically speaking, the contactor is the only viable solution. The loads are too big for other switching means.stephenc wrote:What if any alternative's are there to a magnetic contactor to prevent it from attempting to restart after a power loss ... I live out in the country so this is a must .
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Music isn’t at all difficult. All you gotta do is play the right notes at the right time!
Music isn’t at all difficult. All you gotta do is play the right notes at the right time!
Re: Rotory phase converter questions
to explain the start and run caps ... The pony motor is a 1hp single phase .
I'm not real worried about a little bit of extra noise due to having the pony direct coupled . Once it's built it will go up in the attic where I don't have to listen to it run .
It will also allow me to get it directly above my service panel drasticly reducing the amount of wire needed to hook it up .
I was fairly certain that a magnetic contractor was my only viable option , I had to ask though because this is the only real piece of the puzzle I am missing .
Back to the salvage yard tomarow to see if there's one to be found .
Something else just popped into my head while I was out mowing grass .
Is there any reason to not run a three phase welder on a rotory converter ?
I don't have a three phase welder , but I see them sell dirt cheap at auctions quite frequently. I could use a good welder .
I'm not real worried about a little bit of extra noise due to having the pony direct coupled . Once it's built it will go up in the attic where I don't have to listen to it run .
It will also allow me to get it directly above my service panel drasticly reducing the amount of wire needed to hook it up .
I was fairly certain that a magnetic contractor was my only viable option , I had to ask though because this is the only real piece of the puzzle I am missing .
Back to the salvage yard tomarow to see if there's one to be found .
Something else just popped into my head while I was out mowing grass .
Is there any reason to not run a three phase welder on a rotory converter ?
I don't have a three phase welder , but I see them sell dirt cheap at auctions quite frequently. I could use a good welder .
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Rich_Carlstedt
- Posts: 1757
- Joined: Sat Dec 21, 2002 12:16 am
- Location: Green Bay Wisconsin USA
- Contact:
Re: Rotory phase converter questions
That does not explain the start and run caps ?stephenc wrote:to explain the start and run caps ... The pony motor is a 1hp single phase .
.........................................
If you use a pony motor for starting, you need NO start caps
Rich
Re: Rotory phase converter questions
There is a start and run capacitor on the pony motor ... single phase .
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John Hasler
- Posts: 1852
- Joined: Tue Dec 06, 2016 4:05 pm
- Location: Elmwood, Wisconsin
Re: Rotory phase converter questions
A three-phase welder will work as long as it does not need a neutral connection.stephenc wrote:to explain the start and run caps ... The pony motor is a 1hp single phase .
I'm not real worried about a little bit of extra noise due to having the pony direct coupled . Once it's built it will go up in the attic where I don't have to listen to it run .
It will also allow me to get it directly above my service panel drasticly reducing the amount of wire needed to hook it up .
I was fairly certain that a magnetic contractor was my only viable option , I had to ask though because this is the only real piece of the puzzle I am missing .
Back to the salvage yard tomarow to see if there's one to be found .
Something else just popped into my head while I was out mowing grass .
Is there any reason to not run a three phase welder on a rotory converter ?
I don't have a three phase welder , but I see them sell dirt cheap at auctions quite frequently. I could use a good welder .
Re: Rotory phase converter questions
The RPC you are attempting is the
Ferraris-Arno method. Although the 3 phase motor will run (at reduced power), it will not self-start. Once the motor is running on single phase, the eddy currents in the rotor will induce an EMF in the in the unenergized windings that we can utilize to run other 3 phase motors, I am not a fan of using capacitors to pervert the single phase input to permit a shift in phase enough to start the motor, as it remains in the circuit during the run, and can cause undesirable interactions with the generated current. I think the pony is the only way to go, and is the way I constructed my converter years ago. At the time, I posted under Ferraris-Arno, and as far as I know, its still there.
My design used 3 contactors ( 1 double throw), and is actuated by momentary push buttons at multiple locations. The first contactor is the start/stop and power interruption control The output of the first contactor actuates the double throw contactor through the centrifugal switch on the pony, which is no longer connected to the start winding. Both the start and run windings in the pony are paralleled and connected directly to the NO (normally open) contacts. When the pony, and the RPC, comes up to speed, the centrifugal contacts open, the DPDT contactor drops out, and the power from the first contactor to the 3rd contactor, which places the larger motor that will be the RPC in the circuit, as well as connecting the 3rd side of the delta to the output , which is now 3 phase.
The pony, and all of it's electrics, is completely out of the circuit, and just coasts.
One hint! Isolate the RPC from the structure, preferably on the floor on rubber, as mine telegraphs the vibrations to the wall, and is noisier than it has to be.
Bill Walck
Ferraris-Arno method. Although the 3 phase motor will run (at reduced power), it will not self-start. Once the motor is running on single phase, the eddy currents in the rotor will induce an EMF in the in the unenergized windings that we can utilize to run other 3 phase motors, I am not a fan of using capacitors to pervert the single phase input to permit a shift in phase enough to start the motor, as it remains in the circuit during the run, and can cause undesirable interactions with the generated current. I think the pony is the only way to go, and is the way I constructed my converter years ago. At the time, I posted under Ferraris-Arno, and as far as I know, its still there.
My design used 3 contactors ( 1 double throw), and is actuated by momentary push buttons at multiple locations. The first contactor is the start/stop and power interruption control The output of the first contactor actuates the double throw contactor through the centrifugal switch on the pony, which is no longer connected to the start winding. Both the start and run windings in the pony are paralleled and connected directly to the NO (normally open) contacts. When the pony, and the RPC, comes up to speed, the centrifugal contacts open, the DPDT contactor drops out, and the power from the first contactor to the 3rd contactor, which places the larger motor that will be the RPC in the circuit, as well as connecting the 3rd side of the delta to the output , which is now 3 phase.
The pony, and all of it's electrics, is completely out of the circuit, and just coasts.
One hint! Isolate the RPC from the structure, preferably on the floor on rubber, as mine telegraphs the vibrations to the wall, and is noisier than it has to be.
Bill Walck