### Overview

I simply want .. as a modeler .. to logically wire transformers to my structures. I found this YouTube page – Northwest Lineman College – which has what looks to me like really good information. If someone who is “in the know” .. could translate this into simple diagrams that we modelers could use and even understand would be a ‘good thing’. I suppose what I really would like is a matrix showing wires coming in .. single, dual, triple, quad primary and then the various secondary lines .. why we might want different primary lines .. what we need for the secondary’s.

### Three single-phase distribution transformers connected to a three-phase three-wire ungrounded delta primary-voltage system to obtain three-phase three-wire delta secondary service

Figure 4-21 shows the proper connections for three single-phase distribution transformers connected to a three-phase three-wire ungrounded delta primary-voltage system to obtain three-phase three-wire delta secondary service.
The illustration is for a 2,400-volt primary system and voltages would be connected the same. Single-phase transformers with secondary windings constructed for voltage of 240/480 should be used to obtain 480-volt three-phase secondary service.

### Three single-phase distribution transformers connected to a three-phase four-wire grounded neutral wye primary-voltage system to obtain 208Y/l20- or 480Y/277-volt secondary service

Figure 4-22 shows the proper connections for three single-phase distribution transformers connected to a three-phase four-wire grounded neutral wye primary-voltage system to obtain 208Y/l20- or 480Y/277-volt secondary service

### Three single-phase distribution transformers connected to a three-phase three-wire ungrounded neutral delta primary-voltage system to obtain 208Y/l20-or 480Y/277-volt secondary service

Figure 4-23 shows the proper connections for three single-phase distribution transformers connected to a three-phase three-wire ungrounded neutral delta primary-voltage system to obtain 208Y/l20-or 480Y/277-volt secondary service.

### Using two transformers to obtain three-phase service, for a delta primary circuit

The proper connections, using two transformers to obtain three-phase service, for a delta primary circuit are shown in figure 4-24.

The capacity of the two transformers is now, however, only 58 percent instead of 66 2/3 percent of what it would appear to be with two transformers.