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Motor maths - this makes no sense

Discuss Motor maths - this makes no sense in the Commercial Electrical Advice area at ElectriciansForums.net

Rockingit

Rockingit

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I've got a large USA artist music tour starting soon across Europe so we're having to sort out lots of reducer transformers etc, no big deal. But this has me stumped.... A USA manufacturer of a moving platform is requesting a 208v transformer @ 30A for the platform, but having doubled checked for making sure I've got the right kva for it, they've sent me the following data plate..... but are adamant on 208v. Now very confused.

[ElectriciansForums.net] Motor maths - this makes no sense
 
That goes without saying!!
 
I’m just imagining… opening night and whoever is standing ready for the grand entrance… the motor is just sitting there, buzzing… a little shake.

You going to be involved with Eurovision if it comes to UK?
 
Without the wiring diagram it’s hard to tell.
I wonder if the machine has its own step up/isolating transformer so it can be used in the USA?

if it was being permanently relocated to the U.K., I would be looking at removing it and supplying 400v to it.
as it is a temporary thing, I would supply it with the 208v as requested
 
Isn't 208V what you get across 2 phases of a 3 phase supply in the US?
Single phase motor intended to be used off of a 3 phase supply with no neutral?
 
brianmoooore said:
Isn't 208V what you get across 2 phases of a 3 phase supply in the US?
Single phase motor intended to be used off of a 3 phase supply with no neutral?
Click to expand...
Iirc they just use fewer winding on the transformers, rather than having in and thr top and put at thr bottom, thr out may be halfway down the coins so fewer turns, fewer turns giving less voltage?
 
If that's the correct plate on the actual motor, check that it's in delta and plug it in.
Is there a possibility that there's other gear associated with this that does require 208V?
 
brianmoooore said:
That's what it'll be, a 208V - 400V 3phase transformer. Link it out of circuit.
Click to expand...
That was what I’ve ended up figuring. I’ve zero interest or remit to mess about with it just because someone else has been a twit, though.
 
littlespark said:
You going to be involved with Eurovision if it comes to UK?
Click to expand...
No idea mate, I’ll be happy to survive into the autumn at this rate! Got on a flight to Stockholm this morning and my next actual weekend at home is October!! In between I’ve got a zillion shows all over the planet.
 
Had it been a US-made motor I would have ventured that it's secretly 12-wire and has its windings connected in parallel delta. But as a UK-made motor that's vanishingly unlikely and anyway it would give the correct voltage for 50Hz operation not 60Hz. Therefore I agree with the above that there's a transformer built in somewhere with 208V input.

I wonder whether they have accounted for the difference in speed on 50Hz?
 
Beware of reducing transformers. If the transformer has been designed for 60Hz it might get rather hot and unhappy on 50Hz and I have seen one that need a big red truck with blue lights when it finaly gave up... Ask them is there a variable speed drive needing 208V input and if so would it be better to specify some of Siemens or Rockwell Automation's finest for a european supply?
 
So just to square the circle with this thread, when I finally got up close and personal with this thing it wasn’t actually that motor at all and was a 208 wound delta, 60Hz. Transformer is doing just that!! (Well…. 50Hz, obviously)
 

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