New toy.

[DavidA]

I've just bought a Denford Viceroy 280 synchro at a very favorable price.

Problem is that it is  (naturally) three phase.

It looks from the info I gleaned from Lathes.com that it will probably be a 1.5 Kw motor.  Haven't looked closely at the lathe yet as it was bought from work and I do know it is a good one.

So,  I need some advice on what is the best way to go to set up a three phase 415 Volt supply that will run this motor.

Do I go for a static convertor or a  rotary ?

Or do I cobble together something using my spare 1.7 Citroen Diesel engine and a three phase gen head ?

I do want the supply to be able to run other motors by simply plugging in.  I don't want a dedicated supply just for this machine.

What do you lot think ?

Dave.

[awemawson]

I'd look seriously at an inverter these days. Presuming that you have a main motor and a suds pump can they be wired delta for 240 V ? - If so then that's the way I'd go with a 240 single to 240 three phase inverter. If not you can run a 415 three phase inverter off 415v single phase by applying the 415 v to two of the three inputs. Derive the 415v from a 240-415 isolating transformer. De-rate the inverter as only two of the three input diodes are being used.

Don't forget the suds pump won't be happy at low speeds if you use the inverter for speed control - perhaps give it it's own small inverter, or replace the pump with a single phase one.

[John Rudd]

You could go for one of the cheap Chinese vfd's from EBay for about  £100 of you could buy a Teco/Imo unit for twice the price..suitably rated of course...either way stick it in a box with a 3ph socket on the outlet and it should serve othe users......
And it depends if the motor is a dual voltage job.....415/220...???

[DavidA]

It really needs to be a 415 Volt 3 phase supply.

Here is the machine.

http://www.lathes.co.uk/viceroy/page3.html

Mine comes with the milling attachment.

Dave.

[awemawson]

Rotary converter then. The Transwave offerings are the best in my opinion. Make sure that the generated third leg is not used for the control relays, although this is less critical with a rotary than a static.

[DavidA]

Andrew,

I notice that Transwave don't appear to mention the output voltage on their site.

Am I right to assume that the rotary converters are all 415 volt ?

Dave

[awemawson]

Both the rotary ones I've owned were. The only choice usually is whether they give a neutral or not. I would recommend getting one with a neutral as it is more versatile than without.

They are a very good company to deal with, and good with phone support. I'll never forget my first static Transwave - had it for several years without trouble, then it fell off it's shelf breaking the internal voltage sensing relay. I rang them up to order a new one, and they insisted on sending me one free gratis, despite me protesting that it was entirely my own fault that it had broken and was years out of warranty.

[Arbalist]

If the motor connections will allow it you may be able to run it off 240V single phase. I ran my three phase milling machine from a single phase supply for several years. You only get 80% of rated power but I never noticed the difference on my mill. Just a thought. Cost me the princely sum of £11 I think for the required capacitor. It sure didn't hinder me selling the mill on either when I moved house. 

[Jonny]

The Transwave are about same price as digital inverters, got both.

I don't use the Transwave due to the noise it generates under load and also not being able to maintain spindle speed with minimal cut, think its 5.5hp running 3hp motor. You will regret it.

Op said not an option for 220v he wants plug and play, that leaves rotary which suffer from spindle slowing, rotary convertor or digital inverter all plug and play.

[awemawson]

I never noticed spindle slowing on my Transwave rotaries.

1st one I had was about 3kW off a standard 13 plug and ran my Bridgeport and my two Colchester Students (Flat head and a round head). Obviously being single handed in the workshop it was rare all worked at the same time, but it did happen ocassionally.

2nd one was a 15kW big beast, but it ran a chiller for my 100kW induction furnace, which was a fixed load - I did manage to blow the 60 amp company fuse with it though  A cup of tea for the EDF bloke who replaced it got it upgraded to 100 amps !

When I ran my Moog Hydrapoint 1000 I made two vast static convertors, one for it's 5 kW compressor, and another for the main machine which had a very big hydraulic pump in it.

[Arbalist]

Dave doesn't specify what "other motors" he wants to run on three phase so I'm wondering at what point it would make more sense to get a three phase supply? Cost must vary a lot depending on location etc but I'd certainly beg the question before looking at converters etc. it won't cost anything for a quote.

[awemawson]

When we moved here I rang EDF for a ball park figure for running three phase into my workshop overhead from the transformer that is less than 50 foot from the building. I was told a minimum of £5K and I budgeted £7K for the work and put in an application.

Within a couple of weeks some yellow coated EDF men came knocking at the door, I assumed due to my application. No, they wanted a way-leave to grant access to their transformer to replace the cables with the new 'bunched' ones.

I swapped a way-leave for my three phase connection 

When they came to re-cable they couldn't get their digger under the guy wires for the transformer poles and I ended up lending them my small one 

[Arbalist]

Nice one Andrew! 

[awemawson]

  oh YES   

They then came back again a couple of weeks later to borrow my 100kVA generator (now sold) that they'd seen me using while they were doing the work here - they were re-wiring in a local village that had a nursing home that needed to be kept live (or at least the patients did!) - it came back with a full tank of red diesel and several bottles of Irish Whisky  (the crew were Irish) 

[DavidA]

I had considered asking about a 3 phase supply.  But as the local sub station is nearly quarter of a mile away I thought it would probably be prohibitively expensive. I am situated right at the end of a cul de sac so probably also at the end of one phase.

The other motors I would run are a small vacuum pump (fractional HP),  and a couple of drills that come with three phase motors.

It would also allow me to use small (<1.5 Kw) motors for other general purposes.

A bit of noise isn't a problem as the rotary would only be running for a few short periods at a time. And as it would mostly be running just the lathe (max 1.5 Kw) which would not be over worked,  I foresee no problem.

Only one tool at a time would be used.

I think a 2 Kw unit would probably do me.

Dave.

[awemawson]

Very often in an urban situation they run three phase down the road, and every third house is on the same phase - done to balance the load

[Pete W.]

Hi there, Dave,

I thought the usual UK urban practice was to wire houses in sequence: red, yellow, blue, red, yellow, blue et seq. down each side of the street.  (For recent installations, read black, brown, grey, black, brown, grey et seq.)

If I'm right, you're probably nearer to a three-phase main than you thought!          

The above applies to underground mains cables and might not apply to overhead distribution.  And I'm not sure about phase sequence with the new colours.

Someone will know!                  

Hi there, Andrew, you beat me to it again!!            

[awemawson]

They do the same on overhead lines. We are on (say) L1 in the house, and our neighbours 1/2 mile away are on L2. Connection is by 'line taps' much loved by cannabis growers who don't think that their profit margin is high enough

[Arbalist]

Hi there, Dave,

I thought the usual UK urban practice was to wire houses in sequence: red, yellow, blue, red, yellow, blue et seq. down each side of the street.  (For recent installations, read black, brown, grey, black, brown, grey et seq.)

If I'm right, you're probably nearer to a three-phase main than you thought!

Yes, that's my understanding as well. Unless you're on an isolated plot three phase should be really quite close by.
As said, nothing lost by getting a quote. 

[DavidA]

I'll inquire about the supply. But I suspect it will be prohibitive.

I have to weigh the cost against my occasional use and the fact that I wont be around all that much longer.

I'm looking at around £500 for a rotary converter that will probably see me out.
I finish work (again) on Thursday(when I'm 70) and the money will get a bit tight. This new toy and it's supply are hopefully the last big expenses I have.  At least they are the last planned expenses.

You all know that old saying ' Your heart says 'yes', but your spreadsheet says 'NO'.  The wise man listens to his spreadsheet.

Dave.

[Arbalist]

You may find this interesting.

Of course a cheaper option may be to fit a single phase motor to the Lathe. That's what I was going to do to my mill before I found out about running it on single phase with a capacitor, that only cost me £11.

[DavidA]

It was actually my first intention to fit a single phase motor.  I have a couple of motors that would do the job.

But looking through the tech data I came to the conclusion that this may lead to problems with the existing control gear. (see link in post Number 3 above) Also I have the original milling machine attachment for this lathe. I just need to bolt it back on.  And,  of course, the miller is also three phase.

So, the rotary converter,  which will give me the ability to run my other (and future) three phase 415 volt machines,  looks better every time I think about it.

Dave

[DavidA]

Arbalist,

I'll have to look at that link later, I keep getting error messages when I try to view youtube videos on this machine.
But I do know the principle of creating another phase,  If I remember correctly you have to adjust the value of the capacitor until all the phases have the same voltage across them.
It is useful for running small dedicated motors.

Dave.

[Arbalist]

Dave, the YouTube link is a guy showing how he made his own Rotary three phase convertor. Could save you some money if you want to go that route. 

I did read this on another site which gives me the impression that Rotary converters are old tech compared to modern methods:

"By the way, all the phase converter is doing is offsetting one of the phases so it is 120 degrees from the others. A rotary converter works by running a 3-phase motor and using the output of that motor to create the third phase. A standard motor can generate power if an external source is spinning it. A digital converter does not have moving parts; it electronically generates the third phase, and thus is much more power efficient. I found that my machines ran cooler and smoother starts after changing to the Phase Perfect."

[vtsteam]

There are several ways to make a 3 phase converter.

One method of making a rotary converter uses a starting capacitor to start a separate 3 phase motor (called an idler) and get it up to speed until it self generates 3 phase power for your equipment. Additional capacitors can be used to tune the voltage of the 3 phases.

Another method of making a rotary converter uses a single phase motor to temporarily spin the 3 phase idler motor to get it up to generating speed. Then power to the single phase motor is shut off, and the 3 phase motor continues to run by itself, and generate 3 phase power for your other equipment. Again, additional capacitors can be used to tune the voltage of the 3 phases.

Then there are static 3 phase converters which do not use an idler motor, they use capacitors to run the actual equipment motor.

Here is a non U-tube link for information (mostly on making a static converter) it also has good information on tuning the phase capacitors for all three methods above.:

http://www.waterfront-woods.com/Articles/phaseconverter.htm