[Linked Image]

This final schematic demonstrates one of the methods of deriving 2 phase systems from a 3 phase source. Notice the 86% tapped coils and the 50% tapped coils.
This is known as the "Taylor Method". I know of one other 3 phase closed delta primary to 2 phase 4 wire connection - which uses 3 transformers. It's similar to this, just tap points are swapped around a bit.

Mostly the 2 phase setups were done by means of an open delta "Tee" connection for the primary, then the 2 phase 3/4 wire output was also connected in a "Tee" arrangement [AKA Scott - TEE connection. Funny, that name seems oddly familiar to me [Linked Image]].
An open delta Tee connection is done with tapped windings, whereas the more familiar open delta Vee connection is just a closed delta with 2 transformers instead of 3.

The outputs here are "Phase 1" [two wires] and "Phase 2" [also a set of two wires].
Between the conductors of a certain Phase, there is a potential [voltage], and each one is a stand-alone phasor [phase].
Phase offset between Phase 1 and Phase 2 is 90 degrees.

This is the infamous 2 phase system - which a simple 1 phase system gets mistakenly quoted as being [Linked Image]

Comments??

Scott SET - the bringer of antiquated AC power systems

my edit is towards incorrect labels on phases - only noticed after posting -

[This message has been edited by Scott35 (edited 05-11-2001).]

Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!