Running a single phase motor from a 3 phase supply

[ericmark]

The auto transformer is the normal method however the created new neutral will not be a true neutral. Seem to remember there was also a wound unit called a reactor I have many years ago used them to get a centre tap without using the earth for radar units in traffic lights. Basic design is a transformer star winding but the secondary is not used. It is so long ago I can't remember the calculations for size.

In the main they are used where the supply is from a delta transformer or generator to get a earth. If I needed one I would need to call in a specialist as this is so unusual.

I think my first call would be to a rewind specialist and ask them for advice. You come across many strange systems working abroad including running an old motor with large flywheel with a star winding and using the star point of the motor to get the false neutral. In the UK I would simply swap motor for a 3 phase one.

 

[Spark123]

My first port of call would be to get access to the distribution board.
I don't think an auto transformer is a good idea, a bog standard transformer with isolated primary 415v and secondary 240v with one pole of the secondary earthed is imo a much better if he decides to go the transformer route.

 

[Jackrae]

It is my understanding that you could also get inverters that convert single phase to three phase, in order to run 3 phase motors from single phase.
Life sadly is never straightforward, I am a fully qualified sparks.............BUT, the supplies in our firm are controlled by a facilities provider, running that elusive neutral will involve considerable cost and at least a 2 month wait, much cheaper to find an alternative solution.

That being the case, can you advise how your plant, offices, canteen etc gets its 230V supply for lighting and 13A sockets etc of there is no neutral ??

 

[Brigade77]

That being the case, can you advise how your plant, offices, canteen etc gets its 230V supply for lighting and 13A sockets etc of there is no neutral ??

I think we're meant to pretend that there is no 240v or neutral anywhere within a 5km radius !

 

[DIYedboy]

Jack..............haven't you read my earlier posts?..........all DB's are locked and are controlled by a different company, of course there a neutrals.................but the neutral bars are in the DB's n'est pas?

Dork...............there you are again.

As the existing single phase motor will be pulling around 15 amps, any transformer will have to be so large it'll be cheaper to bung in a 3 phase motor. Many thanks to everyone that have given useful help

 

[Iggifer]

Can't the DB you need access to develop a fault that mysteriously disappears just before they turn up to gain access?

I don't know what the deal is, but I would assume you might get a quicker response for a fault than an elective change. Then whilst they're there, you can get the neutral sorted for this compressor.

Even if this entails a penalty charge for a wasted callout, will probably still work out cheaper

 

[flameport]

Jack..............haven't you read my earlier posts?..........all DB's are locked and are controlled by a different company,

What happens when a breaker trips because of some minor insignificant problem?
Or a dangerous situation occurs that requires the electricity to be shut off immediately?

 

[DIYedboy]

I have been waiting 2 months for them to hardwire my drill press and grindstone.............a tripped breaker can take 2 days to reset (this involves phoning in the fault to an office in Liverpool and then they will 'prioritise' the urgency)!

Ig and Flame, your suggestions are all good, but I'll never know if/ when they will turn up. It's a lot less aggro to buy the new motor.

The moral of the story is NEVER sub out facilities maintenance

 

[Jackrae]

2 days to reset a breaker trip ?
And one wonders why some industries are going to the dogs.
Sounds like it's time you got rid of the bean counters and for your company managers to get their collective fingers out of their rectums.

 

[SimonH2]

2 days to restore a tripped breaker, yeah that sounds efficient. The mind boggles at whoever signed off on a contract allowing for that - which effectively means you can have days of non-production with presumably no comeback.
Time to look into locksmithing courses nearby - a key skill in locksmithing is being able to pick locks

 

[stillp]

a key skill in locksmithing is being able to pick locks

An angle grinder usually works...

 

[SimonH2]

Croppers are quicker and cleaner - but suffer from the same issue that it's hard to pretend that nothing's been fiddled with later In situations like this, I suspect it's quite important to be able to pretend that no-ones been fiddling - hence picking a lock being a useful trick.

 

[Spark123]

I wouldn't dream of it . Master keys are always a handy thing to have too

 

[ban-all-sheds]

Sounds like it's time you got rid of the bean counters and for your company managers to get their collective fingers out of their rectums.

I think it is time for the company managers to be prosecuted for EAWR contraventions.