On 1/4/22 12:15 PM, Jonathan Chapman via cctalk wrote: > One of the top Google results: > > https://www.engineeringradio.us/blog/2012/02/the-open-delta-three-phase-service/ > > 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. --Chuck
