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how to power 460v 3ph on 240 single?

GLTHFJ60

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15hp is 15hp so it's still going to require the same amperage feed whether it's straight single phase or single to a VFD. I believe the rule of thumb on a single phase VFD is to size the feed wire for 125% of the motor size....so the feed to the 15hp VFD should technically be sized for a 70a circuit.

Amps arent the same when comparing different voltages, say 15hp w/460v vs 15hp w/240v. Also, three phase motors have three conductors to send the amps, meaning less amps per conductor, as compared to a 240v single phase motor.
 

arse_sidewards

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Amps arent the same when comparing different voltages, say 15hp w/460v vs 15hp w/240v. Also, three phase motors have three conductors to send the amps, meaning less amps per conductor, as compared to a 240v single phase motor.
I think he means that the for a 20hp motor you're always gonna need enough amperage on the 1ph feed to get that 20hp regardless of whether you convert it to 3ph or step the voltage up before it gets to the motor.
 

bgaidan

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I think he means that the for a 20hp motor you're always gonna need enough amperage on the 1ph feed to get that 20hp regardless of whether you convert it to 3ph or step the voltage up before it gets to the motor.
Correct.

Simply pointing out the fact that the feed circuit for a single phase 15hp motor is going to need to be sized the same as it would for a 3 phase 15hp motor fed by a single phase VFD (or slightly larger factoring losses from the VFD) so there's no real savings in wiring or circuitry.
 

AlxJ64

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This seems to be where all of the RPC guru's hang out so I am firing off a question in here but might be on the early side.
Looking at picking up a larger mill and it comes with an RPC. Seller has little knowledge of it; story is that he bought the machine, RPC, and tools out of a smaller shop and when he got it home he realized he didn't have enough panel amperage to run it in his tiny attached garage in an older neighborhood.

Anyways, the machine is a 7.5 Hp 440V 3 phase machine (1940s Cinci Mill) and he says the RPC is in fact 220V single ph to 440V 3 ph as he saw the machine running so I guess that means there is a transformer unit involved as well.

The QUESTION.... is it plausible or possible, but may be in bad practice to try and pull 220/240, from the RPC prior to the transformer and use that to run a few other machines of mine that I have not yet bought VFDs for? They are all 3 HP and 5 HP stuff and are a Barnes Gear Drive Drill, Cinci Universal Tool Grinder, medium Colchester "Student" lathe, and a giant WW2 vertical bandsaw. I already have my Bridgeport and larger Colchester lathe on their own VFDs and even the M-Head Bridgie has a VFD rated motor upgrade and is running a Pot to control speed.

Thoughts? I guess I'll know more when I get possession of the RPC setup but I am having to rearrange my shop layout to plan for the Cinci No 2 vertical so might as well plan my electrical needs too.
 

arse_sidewards

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It's a pretty safe bet that the RPC doesn't have a transformer. It's also a pretty safe bet that the motor is dual voltage and wired for 2xx input.

Make sure you completely disassemble and reassemble the Cincinnati so I don't have to do it blind when I do mine. :flipoff2:
 

[486]

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it'll be fine, pretty much no RPC is sized specific to any machine, as the ideal configuration changes with load, and load on machines generally changes wildly. Also, rpc systems work better the more shit they're running, so if anything it'd be a potential benefit to run more junk off of it

unless they're running the step-up then the rpc, but you might be able to set up your other shit to run on 440 too which would save a couple bucks on wire size

just trace out the wires and 'well would you just look at it'
 

GLTHFJ60

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it'll be fine, pretty much no RPC is sized specific to any machine, as the ideal configuration changes with load, and load on machines generally changes wildly. Also, rpc systems work better the more shit they're running, so if anything it'd be a potential benefit to run more junk off of it

unless they're running the step-up then the rpc, but you might be able to set up your other shit to run on 440 too which would save a couple bucks on wire size

just trace out the wires and 'well would you just look at it'

X2
 

AlxJ64

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It's a pretty safe bet that the RPC doesn't have a transformer. It's also a pretty safe bet that the motor is dual voltage and wired for 2xx input.

Make sure you completely disassemble and reassemble the Cincinnati so I don't have to do it blind when I do mine. :flipoff2:
You mean that the Cinci is wired for Dual input V or that the RPC output motor is a dual motor and is wired to output 2xV feeding the 440 to the mill.

I will certainly plan on going through the machine and cleaning it up before it gets shoved into its spot and other machines stacked around it. I'll post a thread on it in here once I get my hands on it. Comes with some tooling and the RPC but its cheap because getting it out of the guy's shop is the real challenge as nobody wants to rent the 12K Forklift for $600 a day and then crib across his yard like he did to get it in there. I have alternate plans.
 

arse_sidewards

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You mean that the Cinci is wired for Dual input V or that the RPC output motor is a dual motor and is wired to output 2xV feeding the 440 to the mill.

I will certainly plan on going through the machine and cleaning it up before it gets shoved into its spot and other machines stacked around it. I'll post a thread on it in here once I get my hands on it. Comes with some tooling and the RPC but its cheap because getting it out of the guy's shop is the real challenge as nobody wants to rent the 12K Forklift for $600 a day and then crib across his yard like he did to get it in there. I have alternate plans.
I mean the motor in the Cincinatti can be wired to accept either voltage as input. Most 3ph motors are this way. Check the data plate and compare with how it's wired.

Don't use a forklift. That's a dumbass move and you'll tip the machine over. These machines are meant to be lifted with a sling around the neck.
 

SomeGuyFromOlympia

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I am in the middle of the exact same thing. I have a wysong 5ft brake that's wired 440. I contacted the MFG for schematics. Not only did they provide me with what they had, they also gave me a breakdown over email of what exactly i needed to switch over to make it run 220. Mine is not bad to convert otherwise i would have run a transformer.

The other story. I cannot stress this enough to not go with Phoenix phase converters. Someone gifted me one for my Bday a couple months back from them and it has been a disaster. Customer service was on a level of stupid that i cannot even put into words. It ended up that this unit supplies 110V to each leg with the unit off. Other than that it works I guess. Dealing with them eventually got heated so i asked about a return policy. I was then given the run around. Since I pissed them off the return policy was no longer valid. Ok, fine Fuck you then.
that's when the owner started calling my girl. (the one who bought it for me). He was harassing her trying to tell her i was an asshole. She may already know that but i ended up having to threaten to call the cops on him. Even after the threat, he wouldn't let it go and called and sent 1 more additional text to her. Fucking prick
In short ill be on my way to American rotary this weekend to get a good one.
I called Phoenix Phase Converters about buying a 60hp set up, the fact that me trying to buy their product seemed like I was a irritation to them. Called back several times and the attitude was consistent
Thant was all I needed to know, if they treat you like that before you give them money, what is the treatment going to be after they get payment?
One big irritation was I had the balls to ask about what freight company they used, Couldn't answer it. I told them that if they used Central transport the deal was off. Still couldn't answer the question and had zero ambition to get it answered

On another note
North American Phase Converters were willing to answer all my questions, including tech and follow up. They were even early on the ship date
 
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AlxJ64

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I mean the motor in the Cincinatti can be wired to accept either voltage as input. Most 3ph motors are this way. Check the data plate and compare with how it's wired.

Don't use a forklift. That's a dumbass move and you'll tip the machine over. These machines are meant to be lifted with a sling around the neck.
He said its not a dual wound motor, which I have a giant Baldor stand grinder thats the same way that I got in a lot at an auction and had hopes of one day running but it only has one set of leads in the box. This thread has forced a better understanding of the RPC setups though. I have a big 15 HP 3 phase motor kicking around too, so may just build another RPC for the remainder of the machines. Its just my personal shop so won't be running multiple machines at once.

Don't worry, I am not forking that thing, I certainly know better. I just moved my whole shop including lathes, bridgeport, big drills, and the only thing that got dumped was a 3k lb floor safe and luckily it was into soft dirt and didn't break the handles or dial. Everything machine related was carried with slings.
 

TTMotorsports

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I had a 3 phase 20" disc sander and it was wider for 460V when I got it. BUT like said above I simply hooked up the wires to the correct wiring for 240V 3 phase and have no problems after that. Also I had a mill that was 460V but i rewired it to 240V as well and ran off a RPC without issue.
 

SomeGuyFromOlympia

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slight derail

I was looking into surge protectors for the 3ph
then that led me to panel single phase surge protectors

anyone have any experience with this?
would a surge protector on the 1 ph before the RPC work?
 

[486]

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No but transformers are. I've built many rotaries but if you have to transform to a higher voltage it's not worth it.

Might as well just get a different motor at that point.
220-440 transformers are occasionally on craigslist for scrap money if you're close-ish to a larger city

ETA: and if you can get one with two separate sets of windings rather than an autotransformer (is that an isolation transformer, or is that only applied to 1:1 ones?) it'd probably smooth out the generated leg quite a bit
 

arse_sidewards

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220-440 transformers are occasionally on craigslist for scrap money if you're close-ish to a larger city

ETA: and if you can get one with two separate sets of windings rather than an autotransformer (is that an isolation transformer, or is that only applied to 1:1 ones?) it'd probably smooth out the generated leg quite a bit
I've seen one once. But the Boston area isn't exactly known for its proliferation of industry so ymmv.
 

78bronco460

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i dont have any place local that i can source parts from so its all going to be ordered online...

when first looking it up, i saw people saying step it up then phase convert, others say the opposite. wanting easy i looked up a plug and play type set up and it was around $5k, at that cost i'll pass on the press brake (i've been wanting to build one for years, but buying a real one would be ideal). i can see $2k plus think

then there is the sizing. clac i used says 460v 3ph @ 13a (90%eff. .9powerfactor?)= 11.25hp

i'm hoping something like this is big enough, seems they get allot more expensive going bigger:


and then i haven't even gone into sizing the transformer, but maybe something like this?


does this seem like a working combo?

i'm not a complete retard, i passed 3ph power systems in college (dont really remember much of the class:homer:) i can wire a home no problem. but this is a bit out of my wheel house. thehelp is appreciated
You need at least 70 amps of single phase 240 to run that machine on three phase.
 
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