Hi-Leg Delta Panel

[roger]

George,

It's not without purpose

it most certainly is. :wink:

Any two-pole (line-to-line load) or three phase load wouldn't see the high leg.

Exactly, it is not a high leg in relation to a phase to phase connection and doesn't exist, it is simply one point of a delta connected set of windings.

The high leg doesn't exist in any system connection, it is a voltage read from two unrelated points.

This is no different (kinda but not really) from taking a reading from a point on an ungrounded winding to earth, you will see some potential difference (especially with a high impedance DMM) but in reality it is unusable (unstable in any case) when connected to a low impedance resistance.

Roger

 

[LarryFine]

Any two-pole (line-to-line load) or three phase load wouldn't see the high leg.

Exactly, it is not a high leg in relation to a phase to phase connection and doesn't exist, it is simply one point of a delta connected set of windings.

Correct. It would really be more accurate to say that any 1-phase or 3-phase line-to-line load would not see the high leg as a high leg, meaning it would look no different to the load than the others.

Any line-to-line load would see only the difference between hot wires, which is equal among all three phase wires. Only the voltage from each to earth (ground, neutral, etc.) would measure different.

The fact that a high-leg-to-neutral happens to be the same voltage as line-to-line on a 208/120v Y system is not relevant; the high-leg-to-neutral 208v is not intended to be used as 208v line-to-line is.

 

[George Stolz]

Good way to look at it. Thanks!