12470 to 208 transformer

I can't seem to find a transformer for 12470 pri to 208 sec. Any
suggestions? Vendors?
I've heard people talk about parallel transformers. If the turn ratios are
the same and impedances are the same is it as simple as hooking two 50kVA
transformers together to get 100kVA? (Wouldn't that be an open delta
instead?)
Please help me clear this confusion!
Reply to
KIP
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By the way is there a chart or cheat sheet that will tell me all those possible configurations? I know the basics like 120/240, 480, 277 but I'm weak on the 7200, 2300 stuff.
Thanks again!
Reply to
KIP
What are you trying to power? Is it three-phase or single-phase? This will help to answer your questions.
Charles Perry P.E.
Reply to
Charles Perry
Then if you want to use overhead transformers, you buy 3 7200V to 120V transformers and connect them wye - wye. You will get 208 volts from phase to phase. If you want a padmounted transformer, you buy a three phase transformer with a 120/208V wye secondary.
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sells overhead distribution transformers, as do others. Three phase padmounted transformers can be had from several manufacturers also, including
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and
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.
What size motor?
Charles Perry P.E.
Reply to
Charles Perry
Square D makes 3 phase dry type transformers in this voltage rating from 112.5 to 3000 kVA. They are listed as voltage code 42.
Didn't check for oil-filled, but I am sure they are just as easy to get.
Reply to
BFoelsch
Search manufacturers' web pages. Or better yet, call them. They will have an application engineer that can make sure you get the correct transformer for your application. Even better, contact a licensed engineer to design the installation.
Charles Perry P.E. no I am not soliciting work.
Reply to
Charles Perry
| By the way is there a chart or cheat sheet that will tell me all those | possible configurations? I know the basics like 120/240, 480, 277 but I'm | weak on the 7200, 2300 stuff.
You have to start by knowing the voltage(s) available, and the voltage(s) you can utilize or need. And of course you need to know if your load must have a neutral or not. Then it is a matter of choosing the configuration to get there.
In some cases you should have a WYE transformer secondary. If the load needs a neutral then you should get a WYE (but if you have to use a DELTA there is a thing called a ZIG-ZAG transformer than can synthesize the neutral). If the load does not need a neutral, then a WYE still works and is preferred, but a DELTA can work.
Understanding the voltage ratio is the next issue. DELTA is simple since it has just one voltage. With a WYE there are two voltages (phase to ground and phase to phase) where the phase to phase voltage is 1.73205080756887729 times the phase to ground voltage. That number is the square root of 3 and you'll only need to use 1.732 for almost all work with it. Many engineers just use 1.73 and for recognizing voltages 1.7 is enough.
Some voltages you might see which can use WYE:
110.000 phase to ground --> 190.526 phase to phase (190) (old stuff) 115.470 phase to ground --> 200.000 phase to phase (Japan industrial) 120.000 phase to ground --> 207.846 phase to phase (208) (USA) 127.017 phase to ground --> 220.000 phase to phase (Mexico) 138.564 phase to ground --> 240.000 phase to phase (rare) 220.000 phase to ground --> 381.051 phase to phase (380) (outside North America) 230.940 phase to ground --> 400.000 phase to phase (outside North America) 240.000 phase to ground --> 415.692 phase to phase (416) (UK, Australia, US military) 277.128 phase to ground --> 480.000 phase to phase (North America) 346.410 phase to ground --> 600.000 phase to phase (Canada, rare in US) 400.000 phase to ground --> 692.820 phase to phase (690) (Europe industrial) 577.350 phase to ground --> 1000.000 phase to phase (US mining) 2400.000 phase to ground --> 4156.922 phase to phase (4160) (US legacy distrbution) 7200.000 phase to ground --> 12470.766 phase to phase (12470) (US distribution)
Reply to
phil-news-nospam
Thank you both.
1.73205080756887729 > times the phase to ground voltage. That number is the square root of 3 and > you'll only need to use 1.732 for almost all work with it. Many engineers > just use 1.73 and for recognizing voltages 1.7 is enough. > > Some voltages you might see which can use WYE: > > 110.000 phase to ground --> 190.526 phase to phase (190) (old stuff) > 115.470 phase to ground --> 200.000 phase to phase (Japan industrial) > 120.000 phase to ground --> 207.846 phase to phase (208) (USA) > 127.017 phase to ground --> 220.000 phase to phase (Mexico) > 138.564 phase to ground --> 240.000 phase to phase (rare) > 220.000 phase to ground --> 381.051 phase to phase (380) (outside North America) > 230.940 phase to ground --> 400.000 phase to phase (outside North America) > 240.000 phase to ground --> 415.692 phase to phase (416) (UK, Australia, US military) > 277.128 phase to ground --> 480.000 phase to phase (North America) > 346.410 phase to ground --> 600.000 phase to phase (Canada, rare in US) > 400.000 phase to ground --> 692.820 phase to phase (690) (Europe industrial) > 577.350 phase to ground --> 1000.000 phase to phase (US mining) > 2400.000 phase to ground --> 4156.922 phase to phase (4160) (US legacy distrbution) > 7200.000 phase to ground --> 12470.766 phase to phase (12470) (US distribution) > > -- > --------------------------------------------------------------------------
Reply to
KIP

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