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thegophoto
Member
USA
12 Posts |
 Posted - 01/14/2009 : 20:45:35
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I have a question about a transformer supplied by a tenant. The transformer is a 75 KVA 240 to 208y/120. At the unit it is 208Y/120 and they want to step up the power to 240(all 3 phase of course). Being that the transformer creates the neutral on the 208y side, and no neutral is needed on the 240 side, does this mean that used in reverse, the "created" 240 delta will not be able to run anything except 3 phase machinery. I will ground the transformer, but not use the X0 tap. Is there any safety issues with this installation? When voltage is measured, it must be measured across 2 of the 3 hot legs and not the neutral, correct? I have spoke to the manufacturer of the trans, and he informed me that this would be an acceptable way to acheive 3 phase 240 delta power, I just wanted to see if any of the industry professionals have done this before, as I have not run across 240 delta with no neutral. Any quick help would be appreciated.
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BrianJohn
Avid Member
271 Posts |
Posted - 01/14/2009 : 20:57:01
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| You can operate single phase 240 VAC loads and 3 phase 240 VAC loads, DO NOT ground the XO, DO NOT connect a neutral to XO, you can corner ground one phase of the 240 VAC side. |
Brian John
Leesburg, VA |
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thegophoto
Member
USA
12 Posts |
Posted - 01/14/2009 : 21:07:47
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So no 120V single phase lines can be connected to this "transformed" panel, correct. By "corner grounding" you mean one of the lines can be grounded on the 240 side in the transformer, what does this do?(I believe one of the lines is already corner grounded).
Thanks for your quick response!! |
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BrianJohn
Avid Member
271 Posts |
Posted - 01/15/2009 : 19:13:31
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| Grounding one corner gives a ground reference for the phases and protects against ground faults, stabilizes voltages to ground, |
Brian John
Leesburg, VA |
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kbsparky
Moderator
USA
1976 Posts |
Posted - 01/15/2009 : 19:54:27
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I believe that corner grounding allows one to use single phase load centers in a 3-phase capacity as well. The "neutral" bar is actually one of your phases.
Much more cost effective with distribution equipment that way  |
-KB
 
Life is uncertain -- Eat dessert first !! |
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208Y/120 to 240 URGENT QUESTION!!!
