I would think a combination of visual examination and voltage readings would do the trick.
If there's no neutral conductor on the service bonded to ground, it must be delta.
If one conductor is grounded and there are only two other service conductors, it will be a corner-grounded delta, and you'll get the same voltage reading between the two hot legs and from each hot leg to ground.
If there are three conductors plus a grounded neutral, it could be wye or 4-wire delta.
Wye will show the same voltage from each phase to ground; 4-wire delta will show the characteristic "high leg" voltage on one phase.
Re: Wye or Delta?#67113 06/27/0607:00 AM06/27/0607:00 AM
Just like a lot of other things, the Americans are conveniently backward. Delta-Star Tranny's are used here to supply LV 400/230V installations. No bad combinations, no 120/240/277/460/480, you name it combinations, why does the US always have to be a PITA and be different??. The rest of the world is 50Hz, Grow up!!. And don't get me started on Metrics.
Re: Wye or Delta?#67115 06/27/0612:44 PM06/27/0612:44 PM
Maybe it is because we have had electricity longer. You guys have been dealing with it, what? 60 years or so? When was it that the US Army wired up that place? ;-) sorry
Seriously, part of the problem here is that we have reminants of the Edison vs Westinghouse wars from the early 20th century and some folks won't change. We are lucky not to have DC grids. Once you come down off the national grid the local power companies are free to offer whatever they want or whatever the customer wants. You can make a case for any of the various schemes that enter buildings. Life might be easier if we did have a single national standard for services but then the IBEW would lose some of the mystique that makes it the sectet society it is.
Metrics is another whole question. That is a commie plot and we think the French were behind it. ;-) Some believe it was just a way to charge the same for a smaller bottle of whiskey. (750 vs a "fifth")
Re: Wye or Delta?#67117 06/27/0604:51 PM06/27/0604:51 PM
I don't think the voltages themselves are a problem - but arrangements like corner grounded delta or 4 wire delta do seem somewhat overly complex for people who see on a dailoy basis you can live perfectly with 4w wye supplies and loads that are either connected in wye or delta.
Re: Wye or Delta?#67119 06/27/0608:55 PM06/27/0608:55 PM
Man, don't get me started on 50Hz! I work sites all around the world, and every time we have 50Hz it's a headache. The voltages aren't that big a deal, but having to derate all these UPS systems because the magnetic flux is saturating the transformer core is just killing me... Wanting a 750kVA and having to pay for a 750 but only getting a 625, man, it hurts. Can't even throw money at 'em to rewire the transformers with a different core because the 50Hz transformers are too big! 60Hz is 20% more efficient, why don't ya'll just give it up and switch to 60Hz? All your motors and transformers would be smaller and cheaper ya know!
The worst is when there is a mix of US and european voltages and frequencies, that tends to get messy...
[This message has been edited by SteveFehr (edited 06-27-2006).]
Re: Wye or Delta?#67120 06/27/0609:52 PM06/27/0609:52 PM
I think corner delta is one of the best solutions out there. If I just have 3 phase loads I can do the whole thing with 2 pole equipment that basically looks/costs like single phase. We did a lot of pumping stations this way. You just need to be sure it gets serviced by qualified people who know what is going on.