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208V Single Phase Unbalanced Current

208V Single Phase Unbalanced Current

208V Single Phase Unbalanced Current

(OP)

This question has been bothering me for a while..  

There are a lot of products on the market that can be connected using a 208V, single phase connection (two phases and one ground).  

Where does the unbalanced load go?  If I connect this equipment to two phases of a 120/208V panel (120 degree shift between phases), I should have an unbalanced load, and this load should return on the neutral wire.  But there is no neutral wire, so where does the unbalanced load go?

If this equipment draws 20A at 0 degs on the A phase, and 20A at 120 degs on the B phase, then I should expect to have 20A at -120 degs on the neutral..  Luckily I don't have to worry about the 20A of unbalanced current on the neutral because the neutral isn't connected.  

Any expert insight would be much appreciated!  Thanks!!

 

RE: 208V Single Phase Unbalanced Current

"But there is no neutral wire, so where does the unbalanced load go?"
There is no unbalanced load.  Every thing that goes out A comes ( ond goes ) back on B.

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RE: 208V Single Phase Unbalanced Current

There is an unbalance because Phases A and B are more than Phase C, which has no current.  As BJC says, however, the current goes out on A and comes back on B, so there is no neutral current.

In = Ia + Ib + Ic

Ia = -Ib
Ic = 0

In = (-Ib) + Ib + 0 = 0
 

RE: 208V Single Phase Unbalanced Current

Self,

You are trying to put your currents in phase with the two line to neutral voltages. This is incorrect. Assuming a resistive load, your A phase current will be in phase with Vab. Ib will be in phase with Vba. Then Ia=-Ib.  

RE: 208V Single Phase Unbalanced Current

(OP)
Perfect, I got it, thanks for all your help!

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