# So many posts about phase conversion to 3-phase



## DFWKen (Apr 20, 2017)

For the last week, I've been sifting through threads here and elsewhere about running a 3-phase lathe on single-phase power mains.  It's making my brain hurt and although I've learned a lot, my concerns are still lingering. 

I'm purchasing the Grizzly G0740 3-phase (2-speed) lathe.  

Adapting a VFD to a 2-speed lathe (especially a brand new lathe) is just too labor and skills intensive.  All I really want is 3-phase power  suitable for  running the 5hp (max) lathe.  I don't care anything about frequency control; the lathe is fully adequate in stock condition for my needs.  Almost all of the controls would have to be wired directly to the VFD for jog, reversal,  speeds,  emergency stop, brake, etc.   I don't want to butcher the lathe with a whole new control panel. 


So it appears that a rotary converter is the ticket.  The lathe has a 5hp 2-speed motor.  I doubt I'll ever use the highest speed at max current draw; so is a 15HP rotary converter really required?  The price jump to build or buy a 15HP rotary converter is much higher than a 10HP.  *Would a 10HP suffice?*

And finally, doesn't anyone make an electronic phase conversion unit that is straight 60hz to 60hz and simply converts from single to 3 phase?  All I want is 3-phase power for the lathe at max 20 amps.   I want to keep the lathe totally stock. 


OH, or maybe simply replacing the motor would be the thing to do.  A 5hp 1750 rpm single phase motor would do it, but I'd probably need to change the drive pulley so that the spindle speed range would fall into useable rpm like other single-speed motor lathes.


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## RandyWilson (Apr 20, 2017)

Even if you could find such a VFD, you would have to bypass the lathe controls.  VFDs do not take kindly to pushing into a circuit that suddenly goes open; aka hitting the lathe's off button.


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## JimDawson (Apr 20, 2017)

DFWKen said:


> So it appears that a rotary converter is the ticket. The lathe has a 5hp 2-speed motor. I doubt I'll ever use the highest speed at max current draw; so is a 15HP rotary converter really required? The price jump to build or buy a 15HP rotary converter is much higher than a 10HP. *Would a 10HP suffice?*



A 7.5 or 10 HP should be more than enough.  We have a couple of RPC expert members that will be happy to offer better advice than I can.


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## DFWKen (Apr 20, 2017)

JimDawson said:


> A 7.5 or 10 HP should be more than enough.  We have a couple of RPC expert members that will be happy to offer better advice than I can.


 
This is such a great source for technical information.  
The new lathe's electrical specs are:
Motors: Main Type........................................................................................................................................... TEFC Induction Horsepower.................................................................................................................................. 5 HP / 2.5 HP Phase.................................................................................................................................................... 3-Phase Amps..................................................................................................................................................... 14A/10A Speed..................................................................................................................................... 3450 / 1725 RPM Power Transfer ............................................................................................................................... V-Belt Drive Bearings..................................................................................................... Shielded & Permanently Lubricated Coolant Pump Type........................................................................................................................................... TEFC Induction Horsepower............................................................................................................................................. 1/8 HP Phase.................................................................................................................................................... 3-Phase Amps........................................................................................................................................................... 0.4A Power Transfer ............................................................................................................................... Direct Drive Bearings..................................................................................................... Shielded & Permanently Lubricated

I don't know if a single-phase motor would be reversible (if indeed the stock lathe is reversing via phase manipulation or simply a gear change in the head).

Ken


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## f350ca (Apr 20, 2017)

This company makes a solid state phase converter, but they aren't cheap.
http://www.phaseperfect.com/p/t/overview
They run silent, occasionally the 10hp lathe will warm it up and the cooling fan comes on but the surface grinder and Hardinge don't work it hard enough. Up to the current limit they don't care whats connected  or how its switched. Same as having 3 phase coming from the panel.

Greg


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## Bob Korves (Apr 20, 2017)

American Rotary https://www.americanrotary.com/ is also a good source of rotary phase converters.  Building your own is also a real possibility, and you can save a lot of money that way if you want to supply the time and effort, and is not that difficult.  There is help available on this forum for choosing components and tuning it to best match your machine(s).


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## NCjeeper (Apr 20, 2017)

A 10 hp rpc should be right for your 5 hp motor.


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## rgray (Apr 20, 2017)

I built one with a panel from this company: http://www.ebay.com/itm/7-5-Hp-phas...id=100005&rk=4&rkt=6&mehot=pp&sd=291141592245

And one from this company: http://www.ebay.com/itm/7-5-HP-ROTA...hash=item43c96424b5:m:mRw0inyQNhk5XqyKSAsR2Dw

And have one of these also: http://www.phoenixphaseconverters.com/

The two where I just bought boxes I found my own 3 phase motor. They are not hard to wire.


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## Silverbullet (Apr 20, 2017)

I went through the same dilemma awhile back. But I decided to build my own RPC, if your only planning on the lathe a 5hp converter should do . But if down the road you add a mill with 2 hp motor three phase you would have to upgrade to a 7 1/2 hp converter. That's why I'd suggest going for a 7 1/2 hp now. 
Ulma doctor , on here will help with what you need to build a nice RPC for half or less the price of a new made store bought model. Get on eBay and craigslist Ck for used three phase 7 1/2 hp motor , even if the shaft is damaged you don't need it anyway. Even look for used RPC , they come up on craigslist cheaper at times. But the contactor 3phase, push button switches , 220 start capacitor, some 220 run capacitors. Enclosure box , terminal block , wires , wire glands, on mine I'm using rubber mounts for the motor, and wheels to move it. Not hard to build it , but watch  handling the capacitors , they can bite if charged. Lots of the items can be picked up used. I forgot the fuse block and three fuses. I think thirty amps will do for your build but Ck with Ulma he's the pro. If I didn't live so far from him I think he'd a built mine.


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## coolidge (Apr 20, 2017)

Bob Korves said:


> American Rotary https://www.americanrotary.com/ is also a good source of rotary phase converters.  Building your own is also a real possibility, and you can save a lot of money that way if you want to supply the time and effort, and is not that difficult.  There is help available on this forum for choosing components and tuning it to best match your machine(s).



I just ordered an American Rotary 5hp the other day.


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## DFWKen (Apr 20, 2017)

Bob Korves said:


> American Rotary https://www.americanrotary.com/ is also a good source of rotary phase converters.  Building your own is also a real possibility, and you can save a lot of money that way if you want to supply the time and effort, and is not that difficult.  There is help available on this forum for choosing components and tuning it to best match your machine(s).



Pricey, indeed!  $3,000 for a 10HP.   Rotary phase converter is in my future.  A 10hp will be much easier and less expensive.


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## NCjeeper (Apr 20, 2017)

10 hp delivered to your door for $720.
http://www.ebay.com/itm/281062664604?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT


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## DFWKen (Apr 20, 2017)

NCjeeper said:


> 10 hp delivered to your door for $720.
> http://www.ebay.com/itm/281062664604?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT



That's not a bad price. Building my own would be near $500 even with a used motor. The 10HP sounds like it'll do the trick. Some sites say 15HP for a 5hp lathe duty application; but the specs seem way over the requirements of this lathe.  Maybe they're for 100% duty cycle at max current. (Which I'll never see)

Will look for a motor first. Building appears simple.  I have experience re building up to 50hp a/c compressor controls. The required components look very familiar.  

So I think I have a plan.  Excited about stepping up to a nicer economy lathe from my old Chinese 10 x 36.


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## coolidge (Apr 20, 2017)

By the way American Rotary told me I'd need 30 amps of single phase for the 5hp RPC I purchased, which I have, but how much are you going to need for a 10hp, just thought I would throw that out there.


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## NCjeeper (Apr 20, 2017)

Going to be running mine off of a 50 amp circuit that have for my welders.


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## coolidge (Apr 20, 2017)

Speaking of electrical which always drains my wallet my new 3ph band saw requires a 3ph 20 amp Square D breaker...which cost me a whopping $99 from American Rotary dang! I thought maybe American Rotary was jacking up the price but I ran the part# and that's what it cost elsewhere.  The 20 amp panel mount receptacle $40, plug end $40, well you get the picture electrical adds up.


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## DFWKen (Apr 20, 2017)

coolidge said:


> By the way American Rotary told me I'd need 30 amps of single phase for the 5hp RPC I purchased, which I have, but how much are you going to need for a 10hp, just thought I would throw that out there.


yeah, 50 amp breakers and #8 wire should do it.  All my shop wiring is in metal conduit and the longest run from the sub panel is only like 15'.


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## Ulma Doctor (Apr 20, 2017)

as a point of information,
a 7.5 hp RPC would suffice for powering a 5hp lathe
as a matter of fact i have run 10 hp machinery from a 7.5 hp RPC without incident. ( i don't recommend the practice, unless you have large single phase input wiring)


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## ELHEAD (Apr 20, 2017)

Bought a static converter off eBay, it came from phaseconverterusa . Suited for my 5 HP grinder. Works great. Wrong item shipped the first time. But customer service was very prompt and made correction in no time flat. Would definitely buy from them again. Oh yeah this only cost appx. $50 last yr.


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## NCjeeper (Apr 21, 2017)

Only problem with a static converter is the motor is going to be running at 2/3rds its capacity. That really makes your lathe speeds goofy when trying to get the right feed/speed for a job.


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## ELHEAD (Apr 21, 2017)

Maybe I am too pragmatic, but most of us tend to use less than 2/3 of the available power we have.
The trade off,  .667 X 5 hp = $50, 1 X 5 = $3000.
 Just my thinking.


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## rgray (Apr 21, 2017)

Ulma Doctor said:


> i have run 10 hp machinery from a 7.5 hp RPC without incident



I didn't know that was possible. Good to know.
I thought I was being all crazy running 6hp from a 3hp rpc (4 machines) But that's mild compared to what you did.


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## Bob Korves (Apr 21, 2017)

rgray said:


> I didn't know that was possible. Good to know.
> I thought I was being all crazy running 6hp from a 3hp rpc (4 machines) But that's mild compared to what you did.


Are you planning to run more than one machine at a time?  If not, you only need a phase converter capable of running the largest machine.  The phase converter only needs to handle the load that is running.  I think I also recollect that turning on additional three phase machines makes them also act to help build the missing phase, i.e., I think (correct me if I am wrong) that you only need to size a phase converter to run your largest three phase motor, even if you turn on additional machines.


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## dennys502 (Apr 21, 2017)

This is the one I bought.   30 Amp breaker.
http://www.ebay.com/itm/Rotary-Phas...018813?hash=item5aee0f06bd:g:5NcAAMXQHDlRdrRl

I bought a 3 phase panel so I could run the lathe, Mill and power feed for the radial arm saw.


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## rgray (Apr 21, 2017)

Bob Korves said:


> I think (correct me if I am wrong) that you only need to size a phase converter to run your largest three phase motor, even if you turn on additional machines.



I've had it told to me that if you have a 3hp rpc and start your 2hp mill, you can now start up a 5hp load.
I don't think you can work with them both under load only one (either) course if you were running the mill you wouldn't start the 5hp unit, but if running the 5hp unit you can't unless the mill is running or you name is Ulm Doctor (jealous teasing)

The old school thinking is get a 20-25hp rpc and you can run a 10hp motor. The guy I got my mill from spent thousands of dollars having a 25hp rpc put together to run the mill. He never got it finished and I bought the mill from him and have been running it for years on a 3hp rpc. (2hp bridgeport)

I think your thinking is the best idea (size the converter to the largest load)


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## rgray (Apr 21, 2017)

dennys502 said:


> I bought a 3 phase panel so I could run the lathe, Mill and power feed for the radial arm saw.



Nice one. I notice the specs say single motor start 5hp total motor run 15hp.
Wonder if they are just being conservative on the starting spec.


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## Reeltor (Apr 21, 2017)

I have a 15hp rotary phase converter.  I don't need one that large but I came across a NOS 15hp motor for $130.  I bought the motor and then the phase converter electronics box.  It was easy to mate the box to the motor and then to the machines.  Getting the motor locally will save you a ton of cash.  I think the 15hp box was only $200 when I bought mine.  You should be fine with a 5hp RPC or if you wanted some cushion then get a 7.5 or 10hp.
I went with a RPC instead of a Static Converter, I didn't want to de-rate the power to the motor.

WNY Phase Converters---http://phaseconverterusa.com/Standard-Series_c_27.html


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## Ulma Doctor (Apr 21, 2017)

just to be clear,
a phase converter, is responsible for getting the intended motor fired off.
some brands will use potential relays others do not.
the potential relay type use potential relays and start capacitors to send a heavy DC boost, in addition to single phase supply of sufficient capacity, to get the 3 phase motor to turn on
these type of converter will send a boost of DC power every time the voltage or current drops below a predetermined threshold.

once the 3 phase motor is turning and has single phase supply, it will create the third leg of power through winding induction of the spinning shaft.
the third leg is lower voltage and electrically retarded in relation to the other 2 phases of supply.

once a 3 phase motor is fired off and it's output is combined with other 3 phase motors, the total 3 phase circuit is stronger and helps compensate for the phase lag
the RPC is merely an extension of the concept , run a motor on single phase to generate 3 phases and operate other motors form the strength of the combined generative capacity


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## ValveInHead (Apr 22, 2017)

DFWKen said:


> For the last week, I've been sifting through threads here and elsewhere about running a 3-phase lathe on single-phase power mains.  It's making my brain hurt and although I've learned a lot, my concerns are still lingering.
> 
> I'm purchasing the Grizzly G0740 3-phase (2-speed) lathe.
> 
> ...


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## Downunder Bob (Apr 23, 2017)

DFWKen said:


> For the last week, I've been sifting through threads here and elsewhere about running a 3-phase lathe on single-phase power mains.  It's making my brain hurt and although I've learned a lot, my concerns are still lingering.
> 
> I'm purchasing the Grizzly G0740 3-phase (2-speed) lathe.
> 
> ...


I have heard that if you put a decent sized (heavy) pulley on the 3 phase converter motor it will help with starting load.


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## DFWKen (Apr 28, 2017)

The new lathe arrived today.  UPS called and said it would be delivered yesterday, but they were wrong.  It missed the truck in Kansas City.  Nonetheless, it's here today.  
so is a 10hp rotary phase converter.  It was listed on Craigslist about 70 miles from my home.  I offered a low-ball offer and he came back with a slightly low-ball price.  I committed and traveled to Burleson, Texas to pick it up.  Tested it on 220 VAC and it started and ran quietly.   

I had also made a low-ball offer on eBay for another rotary phase converter; not expecting to win it.   This one included a manufactured control box and a 10hp motor with a shaft sticking out.  To my surprise, the seller agreed to my low ball offer.  So I paid for it.  Now, I have two nice 10hp rotary phase converters.  Not sure which I want to use for my workshop.  Will sell the other.  

When UPS delivered, the worker said that they're not allowed to drive in allys.  Bummer.  I'd even gone to the local UPS freight office a couple of days ago to make sure that they could deliver via bobtail and liftgate in my rear entry.  They said yes.  Today, they said, "No".   
Without a plan B, I didn't know what to do!  Too far to walk it around back on a pallet jack.  But the UPS guy was very friendly and cooperative.  He understood my plight.  so he drove to the end of the alley where we off loaded.  Then, I used a towing strap and my pickup to pull it about 300 yards up the alley to my driveway.   I tipped him very nicely!  He deserved it.  

Took all the rest of the day and into the night to get it uncased and moved into my workshop.  I have a 4,000 lb shop hoist.  It did the job nicely, although lifting it off the foot-tall pallet was a chore requiring lifting the pallet 8" in several steps with cribbage so that the legs of the shop crane would go under.  With my towing strap, I was able to raise the lathe off the pallet, slide the heavy pallet out,  and lowered the lathe to the pavement (after removing the center panel and brake so that the legs would fit without bending the brake).  Pulled it into my workshop with a come-along and put it in its new home.  It'll be there now for the duration.  It's going to take days and plenty of solvent to get the preservative off.  Then, I'll hook up the phase converter (still not sure which converter to keep and which to resell), and go through the several pages of initial lathe setup.   I think I'll take a break and level it tonight.  

I think I should start a new post about setting up my new 14 x 40 lathe in case anyone is interested.


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## Downunder Bob (Apr 28, 2017)

DFWKen said:


> The new lathe arrived today.  UPS called and said it would be delivered yesterday, but they were wrong.  It missed the truck in Kansas City.  Nonetheless, it's here today.
> so is a 10hp rotary phase converter.  It was listed on Craigslist about 70 miles from my home.  I offered a low-ball offer and he came back with a slightly low-ball price.  I committed and traveled to Burleson, Texas to pick it up.  Tested it on 220 VAC and it started and ran quietly.
> 
> I had also made a low-ball offer on eBay for another rotary phase converter; not expecting to win it.   This one included a manufactured control box and a 10hp motor with a shaft sticking out.  To my surprise, the seller agreed to my low ball offer.  So I paid for it.  Now, I have two nice 10hp rotary phase converters.  Not sure which I want to use for my workshop.  Will sell the other.
> ...


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## Downunder Bob (Apr 28, 2017)

Nice looking machine, will be waiting for install and setup pics and story.


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## DFWKen (May 25, 2017)

Phase converter all wired up with appropriate fused (breaker) power main and supplying 3-phase power to my lathe.  All seems well.  
HOWEVER, the idling current draw of the converter seems excessive.   With no 3-phase load, the converter/motor is drawing 15 amps on one leg and 14 on the other from the single phase power main.  I was expecting much lower power consumption when not under any load other than its own internal friction and power losses.  (like almost zero . . .just enough to keep the Phase Converter spinning.  

Does 14 amps and 14 amps sound correct?


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## Ulma Doctor (May 25, 2017)

14A @ 10hp is quite good for an idling 3 phase motor on single phase supply
is your line voltage closer to 220v or is it closer to 240v?


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## Downunder Bob (May 25, 2017)

DFWKen said:


> Phase converter all wired up with appropriate fused (breaker) power main and supplying 3-phase power to my lathe.  All seems well.
> HOWEVER, the idling current draw of the converter seems excessive.   With no 3-phase load, the converter/motor is drawing 15 amps on one leg and 14 on the other from the single phase power main.  I was expecting much lower power consumption when not under any load other than its own internal friction and power losses.  (like almost zero . . .just enough to keep the Phase Converter spinning.
> 
> Does 14 amps and 14 amps sound correct?



It does seam rather high, I assume we're talking about a rotary converter here. does it spin freely with the power off, , (bearings), what size is the motor? could you be measuring circulating currents by measuring the phases? what is the current draw back at the single phase supply?


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## DFWKen (May 25, 2017)

bobshobby said:


> It does seam rather high, I assume we're talking about a rotary converter here. does it spin freely with the power off, , (bearings), what size is the motor? could you be measuring circulating currents by measuring the phases? what is the current draw back at the single phase supply?



I'll need to go measure the unloaded 220VAC primary to see if it's closer to 240V or not.  

Bobshobby, the current draw is measured at the single phase supply to the 3-phase motor while it is running and there is absolutely no 3-phase load at all.  It seemed high to me and would add a hunk of $$$ to our electric bill if the phase converter was accidentally left ON overnight.  

I was going to mount the converter outside in a weather-resistant enclosure to get the noise out of the workshop.  But that invites accidentally leaving it energized.   I should put a motor timer on the motor start that turns it off in 3 hours unless I extend the time.


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## Ulma Doctor (May 25, 2017)

15a is roughly about 2hp equivalent consumption of the single phase line @230v


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## whitmore (May 26, 2017)

DFWKen said:


> Phase converter all wired up with appropriate fused (breaker) power main and supplying 3-phase power to my lathe.  All seems well.
> HOWEVER, the idling current draw of the converter seems excessive.   With no 3-phase load, the converter/motor is drawing 15 amps on one leg and 14 on the other from the single phase power main.



That might not be energy that you're paying the power company for; there's a phase-angle correction,
which you can check.  Turn off electric water heater and furnace/AC, look at five minutes of 
power-company-meter reading with the RPC running, then turn it off and look at another five minutes.

Some of the current you're measuring is due to the start/run capacitors in the RPC, and doesn't
mean real electric power.    The power meter indicates this, but ammeter measurements don't.


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## Downunder Bob (May 26, 2017)

DFWKen said:


> I'll need to go measure the unloaded 220VAC primary to see if it's closer to 240V or not.
> 
> Bobshobby, the current draw is measured at the single phase supply to the 3-phase motor while it is running and there is absolutely no 3-phase load at all.  It seemed high to me and would add a hunk of $$$ to our electric bill if the phase converter was accidentally left ON overnight.
> 
> I was going to mount the converter outside in a weather-resistant enclosure to get the noise out of the workshop.  But that invites accidentally leaving it energized.   I should put a motor timer on the motor start that turns it off in 3 hours unless I extend the time.



OK you had me a little confused, you said 15A on one leg and 14A on another, I assumed you were referring to phase leads, so am I to assume you are referring to the single phase active and neutral leads,if so they should read the same. I still think it's rather high although Ulma doctor says it's about right. And I suspect he knows more about it than I do. It will be interesting to see how much it draws when running a good 3 phase load.

As for running the RPC outside or in any out of the way place, you could wire up a lamp that will show when the RPC is powered on. A mate of mine did that with his shop compressor, he had a green light next to the remote on off switch.


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## Downunder Bob (May 26, 2017)

Ulma Doctor said:


> 15a is roughly about 2hp equivalent consumption of the single phase line @230v



Mike are you sure that it's about 2HP. I would have thought it would be closer to 4HP. unless it has a very poor power factor.


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## Ulma Doctor (May 26, 2017)

bobshobby said:


> Mike are you sure that it's about 2HP. I would have thought it would be closer to 4HP. unless it has a very poor power factor.


the draw is slightly greater than 2hp on the single phase input, a 3hp single phase motor would draw around 17a full load current
full load current for a 3 phase 10 hp motor running on 3 phase 230v, is about 28 amps


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## Downunder Bob (May 27, 2017)

Ulma Doctor said:


> the draw is slightly greater than 2hp on the single phase input, a 3hp single phase motor would draw around 17a full load current
> full load current for a 3 phase 10 hp motor running on 3 phase 230v, is about 28 amps



Mike, I have just realised my confusion, I'm not used to thinking in terms of 3 ph at those low voltages, here in downunder all our single ph is 240v and our 3 ph is 415 v.As a result I'm thinking of currents roughly half of what you are using. Sorry, thanks for the patience.


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## Ulma Doctor (May 27, 2017)

No worries mate!
We have 240v single phase and 208 or 230v 3 phase as well as 440/460v 3 phase
I have wired up a few machines that came from down under to run on our supply
The machines come in with 415v 5 wire plugs
I omit the blue neutral and i convert the control systems. the remaining 4 wires do the work with 208-230v 3 phase supply to the machine.
The conversions are battle tested and have served many well

All the best


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## DFWKen (May 27, 2017)

whitmore said:


> That might not be energy that you're paying the power company for; there's a phase-angle correction,
> which you can check.  Turn off electric water heater and furnace/AC, look at five minutes of
> power-company-meter reading with the RPC running, then turn it off and look at another five minutes.
> 
> ...



*Interesting, Whitmore.  I'll do that.  I just figured that if my ammeter shows 15 amps, then that's what I'm paying the power company for. 

*


bobshobby said:


> OK you had me a little confused, you said 15A on one leg and 14A on another, I assumed you were referring to phase leads, so am I to assume you are referring to the single phase active and neutral leads,if so they should read the same. I still think it's rather high although Ulma doctor says it's about right. And I suspect he knows more about it than I do. It will be interesting to see how much it draws when running a good 3 phase load.
> 
> As for running the RPC outside or in any out of the way place, you could wire up a lamp that will show when the RPC is powered on. A mate of mine did that with his shop compressor, he had a green light next to the remote on off switch.



*Thank you, Bobshobby.  I'm using a clamp-type ammeter, clamping it around one input lead to the phase converter motor and then the other.  It does seem strange that they're not reading the same current.  All current going into the motor should also be going out, shouldn't it?  But indeed, one leg consistently reads 14 amps while the other reads 15.  *


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## Downunder Bob (May 28, 2017)

DFWKen said:


> *Interesting, Whitmore.  I'll do that.  I just figured that if my ammeter shows 15 amps, then that's what I'm paying the power company for.
> 
> *
> 
> ...



Interesting and somewhat intriguing, I can only assume you are losing 1 Amp somewhere. Is it possible you have an earth leakage problem? Do you have earth leakage breakers on your system or not?  I wonder if Ulma doctor can throw any light on this, as it is my understanding that current in equals current out.


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## Downunder Bob (May 28, 2017)

Ulma Doctor said:


> No worries mate!
> We have 240v single phase and 208 or 230v 3 phase as well as 440/460v 3 phase
> I have wired up a few machines that came from down under to run on our supply
> The machines come in with 415v 5 wire plugs
> ...



Glad you know what you are doing, electricity was not my best subject when I studied marine engineering, sure I get the basics of generation and distribution, even fault finding and repair on a known system, but when it comes to wiring up motors onto a system that is different from their name plate, I'm well out of my depth.  BTW your 5 wire 3ph plug woud have been L1, L2, L3, N and E. If you leave the blue out that is the N does that mean you are usinhg the E (yellow/ green or just green on older stuff ) as your N. Are you wiring star (WYE) or Delta?

The 240v single ph here is about to change to 230v to bring us into line with Europe as they change from 220 also to 230v. We will retain the 50hz and they will keep their 60hz, So it's only a partial common system, but we will avoid the problem we have had for years where asian manufacturers design and build to the much larger European market at the old 220v and just relabel  them 240v for us here in downunder, as a result we have had an unacceptably high level of failures in motors, transformers, and other induction devices  Taiwan has recently and finally caught on, but the rest of asia, China in particular is still a problem.


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## British Steel (May 28, 2017)

Hi Bob,

Most 3-phase machinery doesn't use the neutral from what I've seen, when it does it's to get 240 for a control and low-volt lighting transformer or such - most of those can go across 2 phases using their 415v tappings instead, so no problem losing the Neutral.

 NEVER use the green/yellow Earthing (Ground, USAn) wire for carrying load current, it's there to keep you safe! If used for load and a Disaster happens, e.g. a short to the machine frame, it's intended to keep the conductive parts (and anybody touching them) at local earth voltage (e.g. no volts at all!) so no current flows through you, the user, then the current should either blow a fuse/breaker or (the safer way) trip the RCD/GFI - if load current is passing through, the earth resistance can be enough to raise the machine to a  dangerous voltage although it *SHOULD* trip the RCD/GFI - I've experienced this on green Chinese machines sold here in England with faulty electrics and high-resistance cables direct from the factory... Other importers may be as bad or worse.

The UK changed from 240 to 230 as well, "harmonising" with Europe, but there's a 5% supply tolerance on that 230v, a lot of folk in the UK complained that they weren't going to get the same power per amp and so it would put up prices, then it was explained that the voltage was staying at 240 as 230 + 5% = 241v, similar in the EU, 230 - 5% = 219v... SO everybody's happy, and the Eurocrats get to enjoy long sessions in council with 5-star meals and hotels on their expense accounts, making up more regulations that make no difference to anybody's lives 

One bit of info' re line frequencies, Europe's on 50 Hz, has been since the 40s/50s, as far as I know it's only the US and the "Pacific Rim" countries that are on 60Hz - and using 60Hz kit on 50Hz is more of a problem than the 5% voltage difference, as transformers and induction motors are "Volts per Hertz" devices and need lower applied  voltages for the same current at lower frequencies (somewhere between 15 and 20% lower) - which is why USAn kit sometimes blows on everywhere else's mains, probably why the Asian devices blew, designed for 60Hz? As an example, exporting UK 415v 3-phase kit to the USA works, as their 460 - 480v at 60Hz gives near as dammit the same current, coming back the other way ditto, as their 460-480v kit's being fed 380 - 415 so stays within current ratings - not so good going from 220/60 to 240/50 though, where it should be running closer to 200v... Lets the Magic Smoke out for good 

Dave H. (the other one)

P.S. - Glossary!

RCD - Residual Current Device (sometimes "Disconnect") - has phase and neutral conductors passing through it inside a transformer, any imbalance between phase and neutral currents means current is going somewhere else, i.e. to earth so there's a fault - it trips and disconnects the phase and neutral to keep the appliance / installation safe, usually at 30 milliamps as that's been ruled the max safe current a human can take in about 99% of electrocutions.

GFI - Ground Fault Interrupter - much the same but translated into USAn!


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## Ulma Doctor (May 28, 2017)

bobshobby said:


> Glad you know what you are doing, electricity was not my best subject when I studied marine engineering, sure I get the basics of generation and distribution, even fault finding and repair on a known system, but when it comes to wiring up motors onto a system that is different from their name plate, I'm well out of my depth.  BTW your 5 wire 3ph plug woud have been L1, L2, L3, N and E. If you leave the blue out that is the N does that mean you are usinhg the E (yellow/ green or just green on older stuff ) as your N. Are you wiring star (WYE) or Delta?


Hi Bob,
Yes sir, the green/yellow is earth ground- there is no neutral being used, just 3 hots and a ground lead
90% of the stuff i work on is wired WYE, i have only a few pieces of equipment that use Delta wired motors


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