Scott35 has some configurations cataloged at
https://www.electrical-contractor.net/ubb/Forum15/HTML/000064.html E-C.net Technical Reference Area.
It’s half a megabyte, but there is also
http://www.cooperpower.com/Library/pdf/R201902.pdf and is a good collection of common and mutant transformer arrangements for electrical-distribution applications, using combinations of various 1ø transformers. The figures generally apply to a set of transformers with external jumpers or internally connected like in 3ø unit-substation or padmount installations.
Figure 9 is a ∆-∆ connection and common for older industrial systems or in rural areas where one transformer set is used to feed a medium-sized motor. Figure 19 is a Y-Y connection, and one use is to interconnect different transmission voltages…a variation is a wye autotransformer arrangement like figure 24.
Figure 22 is a ∆-Y connection, and probably most common over the range of transformer configurations used to directly serve utility customers—at high-to-medium- or medium-to-low-voltage. Another ∆-Y application is generator-stepup service to feed transmission circuits where the delta side is connected to medium-voltage generator(s) and the wye side faces the 69-345kV transmission system.
Figure 17 is a Y-∆ connection, and in distribution systems is a little less popular than ∆-Y because of its tendency to act as a sometimes-undesirable ‘ground source’ on the wye side.
[This message has been edited by Bjarney (edited 08-04-2003).]
