Thread: electric motor issue, USA to Australia

Originally Posted by Lumber Cruncher

Finally took off the wrappers and reassembled by Delta Unisaw after moving to Australia from USA in 2005 - my 120V tools, e.g. router, miter saw, have been working fine with a voltage converter, even though I am aware that Hz is different. I thought the table saw would be a cinch as it was already 240V and wouldn't mind the Hz difference that much either - well I pushed the switch but it didn't like the Ozzy power - it ran for about 3 sec then went dead!!! Have I blown it up beyond repair? Will I need a new motor? Is there anywhere I can take it for retrofitting if that is what's needed? Any thoughts would be appreciated as I am an electrical klutz - as you have no doubt realised by now. As far as I know it is a standard Unisaw and should have a "3 HP, single phase, 230 volt, TEFC motor with full voltage motor starter"

Uhh I don't think the 50 Hz thing would normally make any difference except the 16% slower speed which shouldn't matter either way too much. So...what changed in three years? Sometimes capacitors go bad...was there any odour or other symptoms? did any smoke come out? (No smoke being a good sign of course).

Here's a thing: Did you have it wired up for 120 back in North America? If so then there would be terminal connection changes to be made. Also you will have smoked the motor if that's true.

If this is beyond your comfort level I'd remove it and consult your nearest motor re-winding service for a diagnosis.

Good luck

Greg

Isn't 240v in America 2 phases whereas in a Australia it's 1 phase?

That shouldn't matter to a motor...the potential between the conductors is still 240v either way. I have a U.S. made Baldor motor 120/240v that works fine when wired to the 240v terminals. (and I imagine less fine when not)

Possible problem is that at 50Hz the US 220V 60Hz motor doesn't spin fast enough to disengage the starting circuit.
Not sure what the outcome would be, but seem to recall "Dead motor" is one of them


ian

That's a thought, but start capacitors are typically switched out at 75% or less of rated rpm. Since 50Hz should deliver 83.3% of rated speed the centrifugal switch should work ok. I'm going to see if there's any online info about these motors.

Can the OP advise if he had it wired in a 240v circuit originally?

Greg

the saw was used at 240V in USA - never wired for 120V - didn't get any smoke or smell either, just a quick spin and then dead - I thought initially it was due to circuit breaker in the house tripping because of excessive amps but that wasn't the explanation as none of the breakers had tripped and nothing else had gone out - it is related to the motor - the saw has been sitting in a garage for 3 years without use so maybe something has failed internally - I suppose I will have to remove the motor and have it looked at - does anyone have any suggestions where to take such an electrical motor for inspection/repair? thanks

another thing - I had to connect the saw to the power by daisy chaining about three extension cords together as it is located in a backyard shed that does not yet have power - also, I used an USA-AUS adapter that was not able to include the earth pin (against my better judgement but this was just to see if the saw worked) - is it possible that the motor may have sensed it was not earthed and so shut itself down? if so, perhaps there is a reset button somewhere on the motor - thanks

More likely the daisy chaining of 3 extension cords resulted in a substantial voltage drop and may have damaged the motor and/or starting capacitor.

But I'm not an electrician and am only expressing an opinion, not a fact

Originally Posted by Big Shed

More likely the daisy chaining of 3 extension cords resulted in a substantial voltage drop and may have damaged the motor and/or starting capacitor.

But I'm not an electrician and am only expressing an opinion, not a fact

That doesn't seem to me likely to cause anything an ordinary mistimed power failure would cause.

Wiring might be a problem, I don't have a clue whether yanks wire stuff the way we do, and a gap in the earth might be BAD.

I'd take myself down to the local dealer for such goods and asking questions such as "Do you service <insert brandname here> table saws and "Who do you recommend to look at this?"

Or local and call your friendly Delta rep.

The extension cord thing shouldn't be a problem UNLESS one of them is a reel type with a built-in circuit breaker (mine has a 10A breaker hidden in the reel which has caused me grief in the past*. It sure sounds like something is popping during the inrush current phase of motor spin-up. (Where the current spike is much larger than the running current as listed on the motor's nameplate. this is exactly when a too small breaker shows itself.

I'd be surprised if your motor has any but the basic features, and while not an expert by any means, have never heard of a control circuit which looks for the presence of a protective earth.

In my earlier post I hope that I didn't insult you by suggesting that you had overlooked the correct voltage...I have never met you so had to ask the obvious...the perils of internet advice.


I just re-read your post and noted the plug adapter. Those things can be crap too and is a likely culprit.


*I also have one with a fuse in the plug like the British have...maybe?

How long of a run of cord did you use, and is it standard 10 amp cord?

Greg

Also, page 995 of the yellow pages lists the local motor repair joints, havn't used any hence no tips.

Aha Greg

you may have hit on it - one of the cords was a reel type, and I haven't checked it for function since; also the adapter was a very light duty one and could have burned out - which I didn't check; I will look into this further on the weekend - many thanks - if that turns out to be the problem then I will feel the complete dufus, but most appreciative of your insight

by the way - I certainly didnt feel insulted at all - we Yanks are sensitive but not that sensitive

cheers! Jeff

Jeff

My understanding is that single phase 240V US is what we call 2 phase which is 480V.

This would mean that your USA power line into the motor would be two active wires of 120V each. Our system uses both lines to start the motor then it cuts back to one line for running.
I think that you will find that you have supplied the motor with 240V aus instead of 2 X 120V US which has toasted the windings. I think the cheapest way out would be to bolt in a new 3hp 240V single phase Aus motor. Needs a 15amp plug & socket. Careful attention to shaft size so that drive pulley will fit. If a new pulley is required; machined cast iron are best.

Ken

Before you haul it away to hospital, can you temporarily move it closer to the powerpoint? And try it there? That could confirm or eliminate the extension cords, and/or the adapter, as alleged offenders.

I'm not a sparkie BTW.

Joe

Originally Posted by Lumber Cruncher

Aha Greg

you may have hit on it - one of the cords was a reel type, and I haven't checked it for function since; also the adapter was a very light duty one and could have burned out - which I didn't check; I will look into this further on the weekend - many thanks - if that turns out to be the problem then I will feel the complete dufus, but most appreciative of your insight

by the way - I certainly didnt feel insulted at all - we Yanks are sensitive but not that sensitive

cheers! Jeff

The dufus would be the guy who lugged his new inverter welder back to the shop, complete with "this is a piece of crap" attitude only to discover that
A: it was fine, and
B: Those pecky reel cords have a current limiter and
C: That he can be a jerk. and that
D: When a Canadian is a jerk he lets everone think he's a Yank. All part of the service.

On 240v power: The North American scheme involves a centre tapped transformer to get two 120v actives that are 180 degrees out of phase, it is not true two phase power (Although I'm told that some areas of Philadelphia have true two phase-go figure). The potential...the number of volts-between our 240 active and the neutral wire is 240v. The potential between two 120v actives that are 180 degrees apart is the same 240v. The motor's windings can't tell the difference.

Greg