[AMPS] 3-phase fan motor - help please

[Dave Kirkby]

Chris W Tran wrote:

> Monday 24th August 1998
>
> Hello all
>
> I'm building a new HF amp. and the electric motor on the
> blower/fan I have needs a 3-phase supply (it is about
> a 1/3 HP motor)
>
> Can anyone tell me how I can run this motor off the AC
> supply in my house - I have 2 phases available and I was
> thinking of connecting the 2 phases, then a capacitor (or
> inductor) to the 3rd phase connection on the motor.
> Would this work ??
>

The domestic mains in the UK is single phase, not two phases. The live
and neutral have a voltage between them that's 230 V RMS single phase
(325 V peak) - having said that, most places I've checked still seem
nearer 240 V RMS.   Unless you have something really odd, you have
single phase mains.

Industrial places, farms and some houses do have 3 phase mains. My house
has 3 phase mains, probably installed as my house is electrically
heated, and therefore I consume a lot of electricity (one day I will
hopefully get oil heating installed, but gas is not an option in many
rural places, including mine)

I once found an article on the internet  called 'Building a phase
converter - includes self starting' by Jim Hanrahan, revised 11-24-95.
(I've quoted the exact title, date in original format, so there is no 3
between 'a' and 'phase'). You might be able to find it on the internet
(sorry I don't have the web page, but I could copy my printed copy if
you get stuck). This discusses how to run 3 phase motors from single
phase mains. I once looked at this problem. You will find quite a bit
about it on newsgroups devoted to hobbyist use of lathes, milling
machines, saws and other machinery.

The other option, that I once discussed with a motor rewinder, was
getting a 3 phase fan rewound to run single phase. They said this can
often be done, but I have never had it done.

Personally, with a fan as small as 1/3 hp, I would not waste my time,
and just buy another fan. You would probably spend more money building a
converter than the fan is worth.

Dave Kirkby, G8WRB



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