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Phase Perfect - Conversion single phase to 3 phase.

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Chipper5783

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Threads about addressing conversion from single phase to 3 phase come up frequently. Often one aspect of inquiry is how to make 3 phase machines work with as little spend as possible - people have come up with some great solutions. I got into this hobby 35 years ago, and started out with a commercially made, 5 hp rotary converter. The RPC worked great for that first lathe, and made it easy to power the next 8 machines that followed. In all, I think I have 13, 3 phase motors from very small up to 5 hp. The RPC worked well, the drawbacks were that it did not start the lathe well on the higher speed motor setting. With the 4J chuck on I'd get one start and the second start befor too long would trip the RPC thermals. Also, the particular unit was quite noisy (though I have seen others that are much quiter).

I've wanted to play with a CNC machine and when an agreeable opportunity for an industrial machine came up, I took the plunge. This VMC has a 15 hp spindle motor and most of the advise I got was that it was a poor idea to run this unit on an RPC. The best solution would be a Phase Perfect. So off to the store for a 20hp PP. The price tag was painful, it cost as much as the VMC!

Phase Perfect is a solid state phase converter, similar to an RPC in that L1 & L2 pass right through, the voltage balance is essentially spot on and it is rated for motor starting right to the capacity of the machine (20 hp) in my case. Needless to say the 5hp motors start very well (sort of like having 8 new speeds on my lathe to choose from). There is an annoying buzz, which I can't hear as soon as a machine is running.

As a whole shop solution it is awesome. I had to pull a new supply for the converter (it is a higher current device), but for the rest I simply swapped the supply to the 3 phase sub-panel and everything was available to run. The VMC started great (I know nothing about CNC stuff - however that will be another post). I encourage more folks to consider PhasePerfect - and this coming from a person who is a fan of RPC phase converters (and a penny pincher too). I've no affiliation, just a satisfied customer.
 
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f350ca

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I bought the 10HP version 12 years ago. Starts the 10hp motor on my lathe with no complaints but it has a clutch so spins up easy.
That annoying high pitch buzz goes away with age, getting deaf so it doesn't bother me anymore. That lends to my only complaint about the unit, they need a bright indicator light, been meaning to hook up a 60 watt bulb for an indicator, it occasionally gets left on overnight as it sits there pretty much silent.
The big lathe will work it enough to turn on its internal cooling fans, but the Hardinge and the surface grinder won't make them come on unless the shop is really hot in the summer.

Greg
 

dpb

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Do you lose motor power with the Phase Perfect?
 

Janderso

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F350ca,
I am so glad to hear you say that.
I called American Rotary Thursday, just about had me talked into a 15 hp ADX15 RPC to Run my Clausing Colchester 15.
Meanwhile I had some discussions with some friends in this forum that feel the 15 is overkill for my 7.5hp motor.
The Clausing is clutched, full speed until the spindle is engaged.
I bought the American Rotary ADX10. Saved $600. Hope it is ok.
I feel pretty good about it.
 

f350ca

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Having a clutch certainly reduces the inrush current. I've had no experience with rotary phase converters but would guess you'll be alright, the Phase Perfect is designed to start a 10HP motor under load, the clutch just makes it easy.
The Summit lathe I have uses a wet clutch / brake pack. With a heavy part in the 16 inch four jaw it takes it a couple seconds to spin it up.

Greg
 

dfsmoto

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I run a Fadal VMC 40 off my 30hp rfc and am in the process of running more equipment off of it. I almost went the phase perfect route but honestly I think the price is a little on the ridiculous side. Yes they are more efficient but the line that is synthesized sags out almost as bad as a rfc.

What CNC are you running? These old Fadals have a large transformer that all 3 lines go into so the current is basically averaged anyway. Also Fadal and especially Haas like to overstate their hp numbers. The actual in rush of current is surprisingly low on most CNC machines due to the soft starting of the inverter. I know my rfc is Overkill but I run my spindle at 10k rpm almost always. I talked to a guy that was running 3 15 hp cnc's off a 20hp rpc. He had been doing that for years with 0 issues.
 

alloy

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I've been watching the replies on this and I have a Fadal VMC15 I picked up in October. I got a 25hp motor off ebay for $500 shipped and bought a converter panel from Croman Converters for $300. I had to run a new 70 amp circuit in my shop and installed volt meters in the converter panel to monitor voltages. I started the converter up and checked the voltages and had to move the taps on the transformer one position to accommodate the voltage I have. I've been running since October with zero problems. I ran this machine where I work for 8 years and I see no difference in how it acts with the rpc powering it. The phase perfect is cost prohibitive for me where I only have $800 in my rpc.

I have a VFD on my manual mill but now having the rpc opens up possibilities of getting more 3 phase machines without having to spend money on more VFD's. I don't have any plans on getting more machines, but you never know what I'll run across.
 

John Ridley

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I have a much more modest 2HP motor. Very happy with the $99 Chinese VFD I got off Amazon.

For smaller motors like this it's nice having a VFD on each machine so they can be soft start and stopped, and I can program emergency stop and such, plus being able to control RPM per machine.

I guess the reason for buying a big one for a whole shop would be because you have single motors that are that big, don't want to shell out for that big of a converter multiple times and will only ever run one motor at a time?
 

dfsmoto

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I have a much more modest 2HP motor. Very happy with the $99 Chinese VFD I got off Amazon.

For smaller motors like this it's nice having a VFD on each machine so they can be soft start and stopped, and I can program emergency stop and such, plus being able to control RPM per machine.

I guess the reason for buying a big one for a whole shop would be because you have single motors that are that big, don't want to shell out for that big of a converter multiple times and will only ever run one motor at a time?
Another reason for rpc is the older electric motors like true sine wave current and not the chopped off square wave you get from those cheap vfds. I started out with vfds and I'm eventually phasing them out (pun intended!). Except on my lathe. I like being able to jog slowly and fine tune the speed.
 

Bob Korves

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I talked to a guy that was running 3 15 hp cnc's off a 20hp rpc. He had been doing that for years with 0 issues.
Once another machine is started, it acts as an additional RPC in phase with the first one and also in phase with any others added later. A 5 HP RPC can run 100 5 HP motors, as long as they are started one at a time, not all started at once. Bigger motors than the RPC can be run as well, after additional motors are on line. The legs get matched better as more motors are added (As I understand things.)
 

f350ca

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If the single phase power is fed to the RPC and the windings in that motor generate the third leg, then wouldn't the RPC motor have to have heavy enough windings to carry the current required by the load motors. If I understand that correctly then you would be overloading the RPC's windings if you run more load than the base motor.

Greg
 

Bob Korves

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If the single phase power is fed to the RPC and the windings in that motor generate the third leg, then wouldn't the RPC motor have to have heavy enough windings to carry the current required by the load motors. If I understand that correctly then you would be overloading the RPC's windings if you run more load than the base motor.

Greg
They are not in series, they are in parallel. Each machine is pulling power from the mains. Each additional motor is also developing the third leg. You definitely need to supply enough power to run the the sum of the needs of the machines, and wiring to match.
 

Galveston

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Threads about addressing conversion from single phase to 3 phase come up frequently. Often one aspect of inquiry is how to make 3 phase machines work with as little spend as possible - people have come up with some great solutions. I got into this hobby 35 years ago, and started out with a commercially made, 5 hp rotary converter. The RPC worked great for that first lathe, and made it easy to power the next 8 machines that followed. In all, I think I have 13, 3 phase motors from very small up to 5 hp. The RPC worked well, the drawbacks were that it did not start the lathe well on the higher speed motor setting. With the 4J chuck on I'd get one start and the second start befor too long would trip the RPC thermals. Also, the particular unit was quite noisy (though I have seen others that are much quiter).

I've wanted to play with a CNC machine and when an agreeable opportunity for an industrial machine came up, I took the plunge. This VMC has a 15 hp spindle motor and most of the advise I got was that it was a poor idea to run this unit on an RPC. The best solution would be a Phase Perfect. So off to the store for a 20hp PP. The price tag was painful, it cost as much as the VMC!

Phase Perfect is a solid state phase converter, similar to an RPC in that L1 & L2 pass right through, the voltage balance is essentially spot on and it is rated for motor starting right to the capacity of the machine (20 hp) in my case. Needless to say the 5hp motors start very well (sort of like having 8 new speeds on my lathe to choose from). There is an annoying buzz, which I can't hear as soon as a machine is running.

As a whole shop solution it is awesome. I had to pull a new supply for the converter (it is a higher current device), but for the rest I simply swapped the supply to the 3 phase sub-panel and everything was available to run. The VMC started great (I know nothing about CNC stuff - however that will be another post). I encourage more folks to consider PhasePerfect - and this coming from a person who is a fan of RPC phase converters (and a penny pincher too). I've no affiliation, just a satisfied customer.
[/QUOT

Hi. I just got my Southbend model "A" into my garage. My question is this; can I use a step-up transformer before the rotary converter, or would it have to be after it? The lathe motor is 2 speed, 3 phase, 440V only. I also bought an Index 645 mill and it has a dual voltage motor, 3 phase. Supply is 220 single phase. Thanks for the help.
 

Chipper5783

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dfsmoto: The CNC machine is a 1998 Bridgeport VMC 1000. It has a multi-tap power transformer right at the front end (supply voltages can be 208V up to 490V) . I don't doubt that there may have been a cheaper option to upgrade my 3 phase that going to a PhasePerfect. Simply a larger RPC might have worked fine. I've heard so many good reviews on the PP product and they never seem to come available second hand (RPCs come up used in this area several times a year). The BP VMC seems to have a good reputation (plenty of fans and a few detractors), but the repeated warning was that as long as the machine still worked it is a good machine - if I burnt something up, then it truely is scrap. Whether that is true or not, I don't know. To date I have had no significant issues.

Even as a complete newbie on CNC, it has not taken long for it to be preferred over the manual mills (I have two well dressed manual mills, good machines that I've put plenty of hours on - the CNC is no harder to crank out a part, and much easier if there is more than one).

Galveston: I have several 575V machines (a pretty common industrial voltage level in Canada) - I have a 240-575 3 phase transformer after the phase converter. It works great with either the RPC phase converter or the PP.
 

frugalguido

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I used a Phase Perfect for many years because it was the best on running a Deckel CNC. When circuit boards for the Deckels cost $2k+ each and there are multiples of them, I didn't won't to take any chances with other methods, It was very good, clean 3 phase, can run multiple machine off of it. When I moved to a building that had 3 phase power, I sold it for close to what I paid for it originally.
 
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