T/F: X/R ratio, transmission vs distribution

TRUE.

• Transmission lines use large conductors (low resistance per km) and large phase spacing (higher inductance), so $X \gg R$. Typical $X/R$ is about 5–10 for 132–220 kV lines and 10–20 or more for EHV lines with bundled conductors.
• Distribution lines (11 kV, 400 V) use small conductors with close spacing, so $R$ is comparable to or larger than $X$; $X/R$ is about 0.5–2.

Consequences: in transmission lines voltage drop depends mainly on reactive power ($\Delta V \approx QX/V$) and power flow on angle, while in distribution feeders voltage drop depends strongly on real power ($\Delta V \approx (PR+QX)/V$), and $I^2R$ loss is a major concern.