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Circlip
06-29-2009, 03:37 AM
A respected collegue (No Sir John, another one) has a mains electricity supply of 240V 50Hz. He is moving to a location where the supply is 240V 60Hz. So, the question being, does he have to scrap all his 50Hz appliances? The smaller ones aren't much of a problem, but what about things like large fridges, freezers and aircon units? Motors on Machine tools???

Regards Ian.

small.planes
06-29-2009, 03:45 AM
Nope, they will just run a bit faster....

Dave

J Tiers
06-29-2009, 08:15 AM
INDUCTION motors will be affected. They will run at 6/5 speed.

Universal (brush-type) motors won't be much affected.

Most things will be OK, allowing for speed.

Some grinders might be surprising in a not-good way, might want a belt change.

Refrigeration devices will pump 6/5 the refrigerant volume, which can be an issue in certain cases.

AC clocks will gain a surprising amount.

aboard_epsilon
06-29-2009, 09:11 AM
if moving to the USA ..it may be a big problem

they have L1 AND L2...........we only have live and neutral ( L1 or L2 or L3 and neutral).

all the best.mark

thistle
06-29-2009, 10:38 AM
I run 50 hz machines on 60 hz 230v , no problem.

Circlip
06-29-2009, 11:41 AM
Thanks so far Guys, the move is from Malaysia (240V 50Hz) to The Phillipines (240V 60Hz)

Regards Ian.

jimmstruk
06-29-2009, 12:50 PM
My enco mill came from the factory with 2 speed charts, one for50 htz and the other for 60htz. I am assuming the motor was made to use either type of hookup. JIM

SDL
06-29-2009, 03:31 PM
if moving to the USA ..it may be a big problem

they have L1 AND L2...........we only have live and neutral ( L1 or L2 or L3 and neutral).

all the best.mark

And if L1 to L2 =220V and L1 to N = 230V other than the speed difference on motors what is the problem?

Steve Larner

aboard_epsilon
06-29-2009, 03:46 PM
And if L1 to L2 =220V and L1 to N = 230V other than the speed difference on motors what is the problem?

Steve Larner

for motors i suppose so ..what about the electronics .

and i know your ideas of phase converters don't work over hear ..so i assume the two lives wouldn't either .,..when switched ..

there will be transformers on the freezers to run the display and caps on the motors.

i really don't know enough ..but i would be cautious

all the best.markj

thistle
06-29-2009, 04:14 PM
usually only makes one bang.

J Tiers
06-29-2009, 09:24 PM
if moving to the USA ..it may be a big problem

they have L1 AND L2...........we only have live and neutral ( L1 or L2 or L3 and neutral).

all the best.mark

The legend of a big difference lives on......... it NEVER dies........ but it's still wrong.

Even the phase converter designs will work.

Why wouldn't they?

All it takes is two lines 230 volts apart........ the neutral issue is no issue at all, particularly since very few 230V appliances even use the neutral.

aboard_epsilon
06-30-2009, 03:46 AM
The legend of a big difference lives on......... it NEVER dies........ but it's still wrong.

Even the phase converter designs will work.

Why wouldn't they?

All it takes is two lines 230 volts apart........ the neutral issue is no issue at all, particularly since very few 230V appliances even use the neutral.

if we could build a phase converter with a single motor and no caps no transformer..and just have another motor spinning it up to speed then disconnecting the pony motor or pulling on the thing with a bit of rope rapped around it....we would do...but we don't ..i wonder why.

http://www.youtube.com/watch?v=BOPFdFgfH6E

J Tiers
06-30-2009, 09:02 AM
if we could build a phase converter with a single motor and no caps no transformer..and just have another motor spinning it up to speed then disconnecting the pony motor or pulling on the thing with a bit of rope rapped around it....we would do...but we don't ..i wonder why.


Wonder on.... or try it and see that it works.

People have done it, quite successfully. But then, the specific folks I recall were in Australia........ Colonists don't give a rip, they just do it if it needs doing :D

Grounding one lead does NOT make an RPC impossible........

You will get a result that is similar to the old-style "grounded delta" we used to have in some places for 3 phase.... but that system worked, and so will an RPC.

The difference would be that if for some reason your design uses the US 120V to neutral for controls, then obviously some change might be required to the contactor coil voltage....

But, there is no reason whatever otherwise.

Even regular appliances work fine on US 230 V... There is a legend that the neutral wire somehow has less insulation and might break down and kill you...... bollocks.....

Your own safety laws require both wires to withstand the exact same voltage to ground, so that isn't a valid argument.

Some US appliances might not work on your voltage, if they used the US neutral.

But coming the OTHER way is not an issue for any normal appliance or machine I can think of at the moment. There might be a special case somewhere, but nothing common or likely.

aboard_epsilon
06-30-2009, 11:53 AM
well i have a very good memory of questions Ive asked in the past ,,

and i was told that Jim's Rosen's idea may not work for me, back in 2003 here

http://www.practicalmachinist.com/vb/showthread.php?t=102173&highlight=phase


there is somewhere, (cant find it ) a thread with David Cofer.........he was building the same as Jim ..i asked and was told not possible by the Brits on the board

if it does work (bare in mind ..im not going to spend a lot on a 6hp motor ...then finding out it wont) ..will a 6hp three phase motor as in Jim's design make 6hp usable output ..or do i need a ten-hp for that.

because, Ive a problem getting my 5.5 hp expensive RT to power my 5hp car lift...and think now Ive blown caps on the converter by overloading it with the car ramp.

6 hp and above is what i need ..and i need it as cheap as possible.....just to occasionally power the ramp,that's without it going up, with a car on it ..sounding like a car with a flat battery turning over engine on a cold morning.

ramp has extra complication of being three phase and nuetral...for the contactor

all the best.markj

J Tiers
06-30-2009, 11:47 PM
I've no idea why it wouldn't work... but it's cheap to find out.

Rope start (or pony motor, whatever) a motor and hook it up....... then measure the three wires vs one another. If it measures like 3 phase, it IS three phase, which is no more than you'd expect.

Sizing.... usually it takes about 1.5HP for each output HP of load.... so for you, every 750 watts of motor load would take about 1125W input.

Paul Alciatore
07-01-2009, 02:08 AM
Read the nameplates. Electrical specs are often posted there for just this reason.

Circlip
07-01-2009, 04:46 AM
Couple of points I forgot to mention, every Tuesday they have a fish and crab tea, and the broadband connection is absolutely crap at the moment. :rolleyes:

Regards Ian.

John Stevenson
07-01-2009, 04:52 AM
What about Wednesday ?

Circlip
07-01-2009, 04:55 AM
Pasta ------------- and chips.