What is the main purpose of a bundled conductor compared with a stranded conductor?

Bundling reduces corona and reactance at EHV; stranding gives flexibility and strength

Bundling gives flexibility; stranding reduces corona

Bundling increases inductance to limit fault current

Compared with a single conductor, how does a bundle change inductance and capacitance?

Inductance decreases, capacitance increases

Inductance increases, capacitance decreases

How is a bundled conductor built?

Two or more separate sub-conductors per phase held 30-45 cm apart by spacers

Many wires twisted into one conductor

A steel core wrapped with aluminium strands

Two phases laid together in one cable

2081 Chaitra (new course) · 4 marks

Stranded vs bundled conductors

Short answer

Stranded conductor consists of many wires twisted together into one conductor for flexibility. Bundled conductor uses two or more sub conductors per phase separated by spacers to increase effective radius, reducing corona and line inductance in EHV lines.

Differentiate between stranded and bundled conductors.

A stranded conductor is one conductor made of many thin wires twisted together. A bundled conductor is one phase made of two or more separate (usually stranded) sub-conductors held apart by spacers.

Basis	Stranded conductor	Bundled conductor
Construction	Many strands twisted in layers into one conductor	2, 3, 4 or more sub-conductors per phase, 30–45 cm apart
Main purpose	Flexibility and mechanical strength	Reduce corona and reactance at EHV
Used in	All overhead lines (LT to EHV)	EHV/UHV lines (220 kV and above)
Effect on GMR	Slightly lower than solid ( $0.7788r$ for solid; e.g. $0.726r$ for 7 strands)	Much larger equivalent GMR ( $\sqrt{d\,D_s}$ for 2-bundle)
Inductance	Almost unchanged	Reduced
Capacitance	Almost unchanged	Increased
Corona	Little effect	Corona loss and radio noise greatly reduced
SIL / capacity	No significant change	Increased (lower $Z_c$ )
Accessories	None special	Spacers / spacer-dampers
Example	ACSR Dog (6/1 strands)	Twin ACSR Moose per phase on 400 kV

 Stranded (one conductor)   Bundled (one phase)
        o o                   (o)------(o)
       o O o                      spacer
        o o

✓ Answer checked by Claude Opus 5.5 (high effort)

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