MODULE 6 — Distribution

6.1 DC Distribution Systems

Radial System

Simple, cheapest. If fault occurs, all consumers downstream lose power. High voltage drop at far end.

Ring Main System

Loop starts and returns to sub-station. Higher reliability. Fault isolates a segment, others stay on.

Interconnected System

Ring fed by two or more sub-stations. Highest reliability, best voltage profile.

SS SS SS1 SS2

6.3 AC Distribution

3-phase, 4-wire system
$$ V_{Line} = \sqrt{3} \cdot V_{Phase} $$
$$ V_{Phase} = 230V, \; V_{Line} = 400V $$
R Y B 230V 400V