110v motor – 2.2kw – on a domestic power supply?

[ell81Participant @ell81]

OK, so on FB marketplace I have seen a 110v 2.2kw motor, 22.7a. Will I be able to run this off a 240v power supply with a 110v transformer(the type used on building sites)?

I am unsure because I don’t know how amperage works to be honest. 13a plugs and a 22.7a supply? How would this work? Thanks.

[DC31kParticipant @dc31k]

A 2.2kW load on 110v will need a 32A plug and socket.

When you hire a floor grinder from Speedy Hire, they recommend a 5kVA transformer:

https://www.speedyservices.com/hire/speedy/18_0302-h-SPE-DFG-280-5-255mm-Single-Head-Floor-Grinder-110v-49kg

Your biggest challenge might be preventing the 230v to the transformer from tripping when the motor is started. That may require a different curve on the supply breaker.

How do you intend to start and stop the motor?

 

[Neil LickfoldParticipant @neillickfold44316]

So you need to know if the motor is rated 50/60 hz or 60hz.  I have just done this exercise, and then decided to wait and buy the tool made for 220v50hz instead of getting the 110v 60hz. In my case, I would need to get a 220v to 220v Single phase VFD to go from 50 hz to 60hz 220v. Then get a  transformer to get from 220/240v to 110/120v 60 hz.

All this because the unit I was looking at buying uses the 60hz for timing. I was also told that the motor in the unit were known to burn out from over heating running on the 50hz. I can only assume that the reduction in RPM , meant that the fan was not bring the required amount of air through for cooling.  The 220v 50 hz motor and the 110v60hz motors, are rated at the same 27k rpm at 100%

Most likely , if it is just a normal motor, a 3kw stepdown transformer should have enough capacity to run it.  If it was rated for 60 hz, will run at 83% of the rated rpms.

Neil

[Howard LewisParticipant @howardlewis46836]

The UK power supply is a nominal 240 volts, so applying that to a 110 volt motor will overload both the domestic supply (Presumably using a 13 Amp socket and plug, which cannot supply 22.7 Amps)

So in short   DON’T.  You will probably burn out the motor, if the fuses don’t blow, or circuit breakers trip, in time.

Using a 110 volt “contractor” type transformer, if the motor draws 22.7 Amps, together with the losses in the transformer, (22.7 /2 + ?) you will probably be close to fully loading the 13 Amp socket.

(The transformer is actually centre tapped to deliver 55 volts each side of earth).

[BazyleParticipant @bazyle]

The transformer will likely cost more than getting a 240v motor. Is it for a lathe? A hobbyist is unlikely to need more than 1.5kW even if it is an industrial machine like a Colchester triumph. One of the gotchas in picking up a cheap big lathe.
A mill also would typically be 1.5 HP for a vertical and only big one ton horizontals will want 2kw.

[SillyOldDufferModerator @sillyoldduffer]

Yes, but the transformer and it’s plug have to be rated for the job.  And be of the right type!  The first example I found (£90) has two 16A outputs, not a single 32A, and digging into the spec showed it’s not rated for continuous operation.  This one risks magic smoke!

A 110Vac transformer able to supply 32A continuously costs about £150.   And strictly speaking it shouldn’t be plugged into an ordinary 13A socket.

What’s needed depends on both amps and time.   A cheapo 16A transformer will run a lightly loaded 22.7A motor that’s more OFF than ON.  It won’t run a heavily loaded 2.5kW motor that’s more ON than OFF, not for long anyway! How much work is this motor is expected to do, and for how long?

It’s borderline.   Gut feel is a 110V motor is more trouble than it’s worth!  Is it a “bargain”? MachineMart sell a 3HP motor for £186, no need for a transformer, and it will run on an ordinary socket.

Briefly:

Watts is Amps times Volts

and, energy consumed takes time into account – kilowatt hours.  This determines how much you pay and how hot the equipment and wires get.   So a 2.5kW component rated with a 50% duty cycle will burn out if it’s left running for too long.   More to it than amps, though they are a good start.

Dave

[MacolmParticipant @macolm]

A little knowledge may be dangerous, but meddling with what you do not understand may teach you enough to have a bit more knowledge next time!

Anyway, as regards supply frequency for transformers and induction motors, the lower the frequency, the greater the cross section of the magnetic path – er as usual subject to the usual ifs and buts. Many 60Hz motors are designed to work at 50Hz, but if instead the design is close to the bone at 60Hz, use at 50Hz will result in overheating, made worse by any fan which will shift less air at 50Hz. So it really needs to be labelled 50-60Hz to have much chance to be problem free. It is much more likely that a 50Hz motor would work just fine for 60Hz at the same voltage.

[Robert Atkinson 2Participant @robertatkinson2]

Dove,

For AC power (Watts) in inductive circuit (motors and transformers) is not Volts times Amps it’s Volts times Amps times power factor. Volts times Amps is VA. When rating a transformer you must use VA not Watts. If you have a 1kW motor with a 0.9 power factor the transformer must be 1111VA (Watts / PF) so larger than expected.

OP Unless you have a “free” transformer don’t bother.
You could use a autotransformer which would be smaller, lighter and cheaper than a isolating “site” transformer but does provide the safety improvement.

Robert.

[ell81Participant @ell81]

Thanks everyone. I decided against it in the end – by all your replies it sounded dodgy. So I just ordered a 240v single phase 1.5kw motor. Should do the trick.

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