208 3ph to 230-240 Y transformer

oldsparky52

Senior Member
I'm curious, why that large of a transformer for a 100-amp circuit?

If you have the proper OCP in place, I don't believe the NEC has a problem in under using a transformer's rating. I have heard that transformers might waste more energy when lightly loaded.
 

david luchini

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infinity

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It will feed a 3ph sub panel that is powering a bunch of 240 3ph equipment one is a 100amp welder.

https://www.larsonelectronics.com/p-149825-.aspx?keyword=&gclid=CjwKCAjw96fkBRA2EiwAKZjFTUsOa-CgqEZm09OUjgT-nTEVKNXefRoEe8lD45ow9L7KSo5C-rJOZBoCQuwQAvD_BwE

This is the transformer they want me to get. Sorry it a 75kva not 112 that was wrong
So I'm guessing that this will be a 3Ø, 3wire, 240 volt system without a neutral? If you need to supply any 120 volt loads then a 3Ø,4W Delta secondary might be better. A 240 volt Wye system has a phase to neutral voltage of 139 volts.
 
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Bill 12

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Vallejo, ca
So we are trying to keep from running a new service which would entail changing a main panel to a 400amp and doing a hot tap and 200ft of new wire
 

Jraef

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Very confusing thread; let's try to clarify:

So you HAVE a 208V 3 phase system, right?

They WANT you to supply their equipment with 240V 3 phase, is that right?

If so, on that 240V system, do they need you to have 120V single phase as well?
 

oldsparky52

Senior Member
So we are trying to keep from running a new service which would entail changing a main panel to a 400amp and doing a hot tap and 200ft of new wire
Have you done a load calculation for the new equipment? Is there room in the existing service load calculation to accept the new loads?

And that 112 kVA transformer is overkill for a 100-amp sub panel.
 
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