cctalk Digest, Vol 88, Issue 2

Chuck Guzis cclist at
Tue Jan 4 14:28:55 CST 2022

On 1/4/22 12:15 PM, Jonathan Chapman via cctalk wrote:
> One of the top Google results:
> Really really, there's only two pigs on the pole. And yet, delta power, though at a lower rating than transformer nameplate (vs. if you had three).

As I understand it:

High-leg delta is independent of open- or closed-delta.

Open delta uses two single-phase transformers primaries connected to
phases AB and BC.  Secondaries are series-connected and 3-phase output
is taken from the high end of either secondary and the common connection.

Mostly a cost-savings measure as the efficiency isn't very good.

On high-leg, one of the secondaries is center-tapped  and split
single-phase is fed from the center tap and either end of the secondary.
  Said configuration can be a 3-winding full delta configuration or the
open-delta as detailed above.


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