Electronic – A confusion about radial schemes in power distribution

power-engineering

My lecture notes about distribution systems/radial schemes say the following:

•In this scheme, feeders radiate from a substation in all
directions and feed distributors at one end only.

• SA is the feeder which feeds the distributor BC at its end B.

The lecture includes the following picture of a radial scheme:

enter image description here

Question: How does this form a complete circuit ? Put differently, the service lines are not part of a circuit as far as I can see.

Best Answer

You are looking at a single-line diagram. Each of those feeders is actually a three-phase AC transmission line.

We draw three-phase circuits as single lines to simplify the drawing, because drawing three parallel lines for every single feeder clutters up the drawing and doesn't convey any extra information.