3 phase to single phase?

[lastminute]

Anyone using a 3ph m/c on single ph supply?
Whats the best way to convert?

Thanks for any advice.

Gerry

 

[Myfordman]

Maybe read my paper on the subject?

http://homepage.ntlworld.com/bob.minchi ... Issue3.pdf

 

[lastminute]

Thanks Myfordman, a well written document...sadly I'm baffled by it all!

 

[Myfordman]

Oh! It was written to try and help rather than baffle.
What sort of machine are we talking about?
If you want to send me a nice clear sharp photo of the motor plate so I can read all the numbers, I can try and help further

Email me at [email protected] if you would like me to assist. There is always a way - I've not had a failure yet!

Bob

 

[woodbrains]

Oh! It was written to try and help rather than baffle.
What sort of machine are we talking about?
If you want to send me a nice clear sharp photo of the motor plate so I can read all the numbers, I can try and help further

Email me at [email protected] if you would like me to assist. There is always a way - I've not had a failure yet!

Bob

Hello,

I can vouch for this, Bob sorted me out with an inverter for my Elliott Progress drill press. It is brilliant.

Mike.

 

[lastminute]

Thanks Bob...I've seen a 3ph Startrite sawbench, the supplier is looking to see if he has a single ph in his store.
So I'm just thinking ahead in case I take it with 3ph motor.

Regards

Gerry

 

[Myfordman]

Thanks for the endorsement Mike - would 5% discount on your next purchase be ok? :lol: :lol:

Pleased to hear you are happy with the result.

Bob

 

[wallace]

It all depends on how many 3 phase machines you think you might get. The options are change motor to single, use an inverter which is good for one machine and can offer braking, or a converter which could be static or rotary. I have a static which runs lots of machines but has its problems reduced power. A rotary is better but more expensive

 

[lastminute]

Are single phase motors that are suitable for the Startrite easy to find/fit?
would it be costly?

 

[Myfordman]

For a given power, a single phase motor will tend to be bigger than its 3 phase counterpart.
If the motor is old then the shaft dimensions will be imperial and the common, newer single phase motors will be metric shafts. The distance from the centre of the shaft to the feet will be different. sometime a spacer can be fitted in but it might means different belts
The mountings could well be different too.
So it depends how tight the space on the startrite is and if the trunnion can still swing over the full range without hitting something.

All fixable if you have decent engineering skills and machinery to modify pulleys and cut keyways.
The other route is electrical. Stick with the 3 phase motor it is fitted with and use an inverter or converter. no mechanical issues at all.
The choice between inverters and converters depend on the type of motor whether it is dual voltage (inverter route) or single voltage then converter is one way (as my paper says)
However I can supply modified second hand inverters with 12 months warranty on my work that will run single voltage motors. The costs are similar to a motor change. Your choice is mechanical work or simple electrical changes and I provide all the info you need. But I stress that I am not trying to persuade you to buy anything here as it is against the rules and the mods are tight on this even though I'm only trying to help and I do not profit from it.
Talk to others via PM and they will verify my services. I always offer 30days money back if not satisfied and no one has ever taken me up on that.

Bob

 

[lastminute]

Thanks Bob, a nice and simpler explanation for me.... seems like I have choices now without having to worry.
I await word from my Startrite supplier, re which motor!

Gerry

 

[Myfordman]

Gerry & Other readers.
I have been warned regarding the level of help that I have offered through this thread and so this will be the last post from me in this thread.
My contact details are above and you are welcome to contact me directly. The restriction does mean however that future readers will not be able to increase their understanding of the issues and possible practical solution(s).
Bob

 

[CHJ]

Gerry & Other readers.
I have been warned regarding the level of help that I have offered through this thread and so this will be the last post from me in this thread.
My contact details are above and you are welcome to contact me directly. The restriction does mean however that future readers will not be able to increase their understanding of the issues and possible practical solution(s).
Bob

Bob that is a silly reaction to any comments you have received from a moderator.

I have not been party to exactly what has been said to you but I suspect it was to ask you to refrain from making comments about the supply of equipment (advertising, regardless of profit ) in open forum.

It is exactly the same problem we encountered when you took umbrage following requests to curb posts on a similar line when demonstrating products while signed in as "9fingers"

If you cannot see that such phrases as:-

.........
However I can supply modified second hand inverters with 12 months warranty on my work that will run single voltage motors. The costs are similar to a motor change. Your choice is mechanical work or simple electrical changes and I provide all the info you need. But I stress that I am not trying to persuade you to buy anything here as it is against the rules and the mods are tight on this even though I'm only trying to help and I do not profit from it.
.........Bob

are likely to cause complaints from legitimate advertisers or commercial suppliers of products who we as moderators block etc. then I am personally at a loss.

 

[memzey]

Please, please, please let's all play nicely. I'd personally be gutted if Bob stopped posting or felt he couldn't contribute freely. At the same time I understand the point on treating all parties fairly even though bob always seems to offer excellent advice and support to forum users.

 

[Myfordman]

OK I'll break my own rule straight away.
The difficulty I have is saying the there is a solution to 415v 3 phase motors from single phase supply, without saying who can provide it.
The answer to that is myself or one other commercial supplier as far as I know.

My intention in saying I'd not post further in this thread is to minimise/eliminate the risk of an outright ban - I've been there before and not intending to go there again.

I will help out in other threads when I'm able so Memzey you should not be concerned.
Possibly best if this branch of the thread is not continued further and we just stick to helping the OP

Bob

 

[woodpig]

It depends on the machine and the type and orientation of the motor but I ran a three phase milling machine on single phase with nothing more than a single capacitor and swapping a few wires over in the terminal box. I happily used the machine like that for several years. You only get about 80% of the motors rated power but nobody told the motor that and it never stalled on me. :lol: it also made selling the machine easier when a house move came up.

 

[Random Orbital Bob]

Thanks for that Bob, I think many of us appreciate that individuals that offer a lot of skill and expert knowledge in a niche area (like motors) yet simultaneously operate a commercial enterprise walk a bit of a tightrope in open forum.

Perhaps it might be helpful to make it a little less opaque for people so you can refer back to this thread.

Bob runs a modest motor and accessories (eg inverters et al) supply and repair business which is less about profit than it is about Bob's vociferous interest in the topic area. He has helped many forum members over the years with his wealth of knowledge and expertise and has gone to the trouble of documenting a very useful "paper" helping to demystify some of the "black art" which we all associate with the dreaded "windings" and "phases". Bob can be reached through the normal channels if forum members wish to discuss his professional capability.

What the moderators must ask everybody to respect is that messages promoting businesses, commercial interests etc are not allowed in open forum because within a short period the forum would simply be awash with sales spam, ruining it for all. This isn't a blue sky notion that "might" happen, it is an ongoing threat which the moderators (largely invisible to forum members) are busily removing on a daily basis. Voluntarily I might add.

So.....heads up. Bob has a motors business...but he cant talk about it, and neither can Custard, or Richard Jones or Peter Sefton etc etc etc ad nauseum. But what the smart ones do is contribute intelligent and useful insights into threads and that way become known. It's just a more subtle way of promoting one's value without actually putting up a price catalogue! I'm sure we all get the message.