can you run a 3 phase motor on single phase power?

[onetreeforge]

I have had this problem for a long time, there is no 3 phase power where I live, just 240 volt single phase, but I just been told its sometimes posable to wire a 3 phase motor to run on a single phase?. now I have a power hammer and need 3 phase.

 

I saw people had made converters on the net but this looked very complacated, any info would be very helpfull 

[Thomas Dean]

short answer--no.  buy a single phase motor. you can do that cheaper than buying a converter and the elctric co just south of me was going to charge a friend $4,000 to run an extra line to his shop for him to have 3ph.  My elect. co-op told me whenever to let them know and they will do so for free! at the moment I have no need for it.

[Steve Sells]

IF you have a 3ph delta connection I can rewire the motor to run on the remaining two lines at about 60% power, to keep things moving until full power is restored, a 3 ph Wye coinnection, no.  this is where the stories about running a 3ph motor on single phase comes from, its not a long term solution. only temporary.

 

 If you have single phase you can get a phase converter which at best is about 80% effecent.  the best bet is buy a new single phase motor,  its cheaper in the long run

 

IBEW 305 Electrician

[781]

Google 3 phase converters. It is possible to wire one with capacities or run off a motor that is running but not powering a machine. You can only run 3/4 of the idle motor so a 10 HP will run a 7 1/2 HP but up to 50 HP by combining smaller motors. You also need to wrap a pull cord around the shaft to start the rotation.

[SoCal Dave]

I looked into the same situation you are dealing with.  There was also the issue of stealing power from my home while running the 3 phase motor.  So, I did get a new single phase "general farm motor" for a power hammer and it works great without any side issues. The phase converter wasn't cheap either.  

[onetreeforge]

Thanks for the replys guys, I was looking thrugh google alot and they say I would loose upto 80% of power and burn the winding out, I see people have made converters out of a cople old motors, one spinning the other then run the 3 phase wires to the motor to be powered.

 

I was looking at the powerlines and the 3 phase cables are about 2 miles from my shop, they will never ever run them to my place.

 

 

How meany HP would I need to runn a 35 pound spring hammer?

[Thomas Dean]

I have a 1hp motor on my 25# Little Giant, at 1750rpm. what the book recommends. I'm sure it would be plenty for you 35# hammer.

[onetreeforge]

I just bought a one and half HP Crompton parkinson single phase motor off the internet, will see if I can pick it up on sunday

[onetreeforge]

I was looking on youtube and people had done that, I wonder it that would run a 3 phase mig?

[dimenickel]

well, it depends

i'm not sure about electronic stuff or welders...as my experience is with hydraulic's

 

you want your rotary to be much bigger for things that have a hard start

eg.. for my hydraulic press i use a 7.5hp work motor and needed a 15hp rotary phase converter  ( motor and box ) to be able to use it

 

the advantage is that you can buy the cheeper industrial surplus motors ( which are more durable )

 

hopefully others will chime in about welders ?

[cvmikeray]

TECO VFD 1-3 HP should do the trick.

Here is a conversion I did for a South Bend Lathe, but the concept is the same.

 

http://www.youtube.com/watch?v=llTO2X-jOIA

[timgunn1962]

According to his profile, the OP is in New Zealand. The power supply system there is, as far as I know, similar to much of Europe and rather different to the USA.

 

A single phase domestic supply is usually one phase of a 415V phase-phase 3-phase supply as the live, together with a Neutral, taken from the Star (Wye) point, at Earth (Ground) potential, giving 240V Live-Neutral.

 

A phase converter to provide 415V 3-phase can be built, but needs a 240-415V step-up transformer as the first part. This adds expense and complexity. It can still be a viable DIY project, but is apt to become a hobby in itself, rather than something knocked together in a weekend to let you get on with your real hobby.

 

240V input VFDs will usually give 240V 3-phase output. There are rare examples that include a step-up stage to 400V and give their output at 400V phase-phase. They tend to be hard to find and very expensive.

 

Most small 3-phase modern motors (up to about 3 kW) have 6 terminals in the connection box and can be wired in Star (Wye) for 380-440V, or Delta for 220-240V. Above about 4 kW, they tend to be wireable for roughly 400V in Delta and 700V in Star. This is to allow "Star-Delta" starting, which greatly reduces the current draw on initial startup when compared to Direct-On-Line (across-the-line) starting. It's something that tends to be seen on big industrial motors and doesn't seem likely to be of interest to many of us. If you are buying a 3-phase motor to use with a 230V VFD, it's worth noting that the change from 230/400V to 400/700V is not at a standard motor size; it needs checking for the specific motor.

 

Many older motors only have three terminals in the connection box, so can only be run on the original design voltage. Reading between the lines somewhat, I get the impression the OP probably has an old 415V motor on a similarly old Power Hammer.

 

The most practical solution seems to be the one taken: buy a single-phase motor and fit that.

 

I was discussing VFDs with someone who knows a bit about PHs a while back. He seemed to think a VFD on certain types of PH would be useful for the gentle stuff. As I understand it, the blow energy changes with the square of the speed, so it seems like it could work very well. I don't know enough about PHs to have an opinion.

 

The obvious way to find out would be to run a PH from a VFD. However, this is not necessarily a good idea, as most older PHs have old motors. It should be fine on a new one though.

 

The waveform from a VFD is very hard on old motors, and the winding insulation can break down very quickly. It's not usually a problem if the motor has been rewound in the last 30-40 years, as the insulation will be whatever was in general use at the time of the rewind. Motors from about 1970 onwards don't seem to be a problem, at least in my limited experience.

 

As for running a 3-phase MIG, it's worth checking whether it's really 3-phase, or just uses 2 phases of the 3-phase supply to give a single phase at 415V. If the latter, it would run from a step-up transformer.

 

Alternatively, there are some pretty meaty single-phase MIG welders available. I've just got an Oxford S-MIG 410-1 at work and it seems to be a very capable machine.  http://www.weldingsuppliesdirect.co.uk/welding/Oxford-S-MIG-410-1-SMIG4101.html

[ianinsa]

Your power power setup is similar to ours, so it's often a dodle te sort a small ie. less tham 5hp three phase with single phase by adding a simple capasitor. take a pic of your plate and your connection on the top of the motor and maybe we can make a plan. I've also made a phase convertor for my Durban house, it works but is expensive and quite a mission. Regards Ian

[onetreeforge]

Thinks for all the info guys, I should have made it more clear that its a diffrent system here,

 

 

Single phase MIGs and arc welders, motors sell for alot more money, I have been offered so much big 3 phase machinery for free and had to turn it down

 

Here is a picture of the powerlines witch finish by my shed, the top ones are high voltage, the lower ones go thrugh a transformer then into the house.

[Steve Sells]

I dont know where you got your electrical training from , but I would like to see where you came up with the 50 foot comments?  NEC 310-16 is clear about voltage drop calculations and amperage ratings are derived from that,

 

I worked hard for my certifications, and I have seen how guess work can burn down a building or get some one killed with advice to people to do it themselves. 

 

Please get real electrical advice from people that do know about this stuff.  Being told to DIY when these questions show one is not experianced is unprofessional, dangerous and fool hardy.

[Francis Trez Cole]

yes VFD is the ticket check out http://www.waynecoeartistblacksmith.com/WayneCoeArtistBlacksmith.html you will find him on Iforgeiron as will

[ianinsa]

Francis, Wayne has some neat stuff however firstly NZ is half a world away and secondly his domestic power is 240V 50hz and here I speak under correction- it's probably not what Wayne stocks.

Steve, indirectly he has asked you - a suposed expert - and you were'nt exactly full of helpfull advice. When one is drowning it is preferable for someone to throw you a pair of childrens waterwings, than to have someone with a lifepreserver in his hands waving it about saying "that idiot should have thrown him one of these!". I don't wish to pick a fight nor squabble(I know some guys and I'm not saying you have very fragile ego's) but if you know how, then tell the man how to do it affordably and if you don't then say so!

Regards Ian

[Steve Sells]

Francis, Wayne has some neat stuff however firstly NZ is half a world away and secondly his domestic power is 240V 50hz and here I speak under correction- it's probably not what Wayne stocks.

Steve, indirectly he has asked you - a suposed expert - and you were'nt exactly full of helpfull advice. When one is drowning it is preferable for someone to throw you a pair of childrens waterwings, than to have someone with a lifepreserver in his hands waving it about saying "that idiot should have thrown him one of these!". I don't wish to pick a fight nor squabble(I know some guys and I'm not saying you have very fragile ego's) but if you know how, then tell the man how to do it affordably and if you don't then say so!

Regards Ian

 

My first reply to this question was given within an Hour of OP, and read:

 

IF you have a 3ph delta connection I can rewire the motor to run on the remaining two lines at about 60% power, to keep things moving until full power is restored, a 3 ph Wye coinnection, no.  this is where the stories about running a 3ph motor on single phase comes from, its not a long term solution. only temporary.

 

 If you have single phase you can get a phase converter which at best is about 80% effecent.  the best bet is buy a new single phase motor,  its cheaper in the long run

 

This was my first post in reply to the question,  And while I do not see much real information added to what I first posted from anyone else, you state you dont want to start a fight, and then say I am not helpful?  You sir gave me insults. I gave honest answers.