I need to install a 220v single phase sewer pump (E-one) to a building that is set up for 3 phase power. Is there an easy way to convert? The pump salesman said I could get a buck and boost transformer at Graingers. I’m no electrician, but I believe that the transformer will only correct voltage and has nothing to do with phase. I know nothing about this. Please enlighten me.
Thanks,
John
J.R. Lazaro Builders, Inc.
Indianapolis, In.
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Replies
Well first you need to identify what kind of 3 phase service that you have.
If it is apartments, large house, office, or small stores then it is most likely 120/208 Wye service. You have 3 legs, each is 120 volts from hot to neutral and 208 from leg to leg.
Some 230 (240) volt motors are speced to work down to 197 (208). If yours is such then no problem. Otherwise you need to boost the voltage up with a transformer.
But I would be suprised if they can supplied the unit in 3 phase.
The other type of 2 phase that is used for more industrial applications is 240 3 phase Delta. The transformer supply one leg (connected between 2 hots) is center tapped and the center tap is the neutral. Thus between those 2 legs and the neutral you have 120 and 240 between any hots.
With that system you would not have any problems.
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
So how do I test to see what I've got? Can I do a simple Wiggy test?John
J.R. Lazaro Builders, Inc.
Indianapolis, In.
Depends on what the Wiggly is rated for. I would not want to get one across 480 unless it and you are rated for that.One concern that I have is that there are other systems such as 480 Y and it uses a separate transformer to generate local transformer to generate 120.What is the usage of the building now? and in the past?Does it have one panel for both 3 phase and single phase loads?What kind of 3 phase motors are installed? Look at the labels and see what voltage(s) it is rated for.If there are only one panel and any motors that you see are rated at 208 and/or 230 or near those values then most likely there is no 480.IF that is the case then youc an measure each leg to neutral.If you get 120 on each leg then it is a 120/208 Wye. If you measure 120 and 2 legs and 208 on a 3rd then you have a 240 Delta system with a center tapped transformer..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Edited 5/25/2008 12:58 am by BillHartmann
I'll do some investigating. I need to clarify that it will be a sparky doing the connections and not me. I was just asking for my own morbid curiousity and prsonal knowledge.
Thanks for the info,John
J.R. Lazaro Builders, Inc.
Indianapolis, In.
"If you get 120 on each leg then it is a 120/208 delta. If you measure 120 and 2 legs and 208 on a 3rd then you have a 240 WYE system with a center tapped transformer."
That should be DELTA.
Also called a wild leg and should/must be orange.
~Peter
Yes, I got both of them backwards..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Single-phase 220 VAC meaning that the legs are 180 degrees out of phase with each other. Each leg is 120 (110) VAC potential to neutral.
Three-phase power has each phase referenced to neutral, each phase at 120 (110) VAC to neutral. However, the legs are 120 degrees phasing from each other.
From the three-phase power you would pick one of the phases which is loaded less than the others. Then run the selected phase (hot and neutral) through a transformer to up the voltage from 120 VAC to 240 VAC. Circuit protection and you're done.
Jim
Yeah, for the most likely case you need a boost transformer to boost voltage from 208 to 240. A sparky who does industrial work will know what to do. Non-trivial but not rocket science either.