SarkariResultOutPYQ
HardAdditional Assistant Engineer (Electrical)2026✓ Editorially verified
PDF

GMD Method for 3-Phase Capacitance

In a 3-phase transmission line, if Dm is the geometric mean distance (GMD) between conductors, r is the radius of each conductor, and ε is the permittivity of the surrounding medium, which expression gives the capacitance per phase for a symmetrically spaced line using the GMD method?
⚑ Report issue

Found a wrong answer, translation, image or source problem? Send it to editorial review.

Answer & Explanation
Correct AnswerC. C = 2πε / ln(Dm/r)

Quick Explanation

For a transposed or symmetrically spaced 3-phase line, the phase-to-neutral capacitance per unit length is C = 2πε / ln(Dm/r), where Dm is the effective mutual spacing and r is conductor radius for capacitance calculations.

Formula / Key Relation

C = 2πε / ln(Dm/r) F/m
GMD Method for 3-Phase Capacitance explanatory diagram

Detailed Explanation

Correct Answer

C — C = 2πε / ln(Dm/r)

Explanation

For a transposed or symmetrically spaced 3-phase line, the phase-to-neutral capacitance per unit length is C = 2πε / ln(Dm/r), where Dm is the effective mutual spacing and r is conductor radius for capacitance calculations.

Key Concept

GMD Method for 3-Phase Capacitance

Formula

C = 2πε / ln(Dm/r) F/m

Exam Point

Capacitance has 2πε in numerator and ln(D/r) in denominator.

Common Mistake

Do not reverse the logarithm; ln(r/D) would make the expression physically incorrect.

Quick Trick

Capacitance has 2πε in numerator and ln(D/r) in denominator.

Common Mistake

Do not reverse the logarithm; ln(r/D) would make the expression physically incorrect.

Exam Tip

Capacitance has 2πε in numerator and ln(D/r) in denominator.

Continue learningRelated PYQs & Exam ContextExam path, knowledge path and deeper practice links.
Study concept · GMD Method for 3-Phase Capacitance →Practice conceptPractice topic
1Previous Exam Appearances
7All Related Questions

Previous Exam Appearances

01 ADDITIONAL ASSISTANT ENGINEER.pdf2026Q. 74

More Questions From This Concept

Same Subtopic PYQs

Same Subtopic PYQsThe capacitance of an overhead transmission line increases with 1. increase in mutual geometrical mean distance. 2. increase…✓ Verified · Practice →

Related Topic & Exam PYQs

Related Topic & Exam PYQsFor a transposed 3-phase transmission line, the mutual distances between the conductors are 4 m, 4 m, and…✓ Verified · Practice →Related Topic & Exam PYQsWhich of the following factors increases corona power loss?✓ Verified · Practice →Related Topic & Exam PYQsWhy are ground wires installed at the top of 400 kV transmission towers?✓ Verified · Practice →Related Topic & Exam PYQsThe type of line support in transmission line does not depend upon the:✓ Verified · Practice →Related Topic & Exam PYQsWhich conductor characteristic is most effective in reducing the corona effect in EHVAC transmission lines?✓ Verified · Practice →Related Topic & Exam PYQsIn an AC distribution system, what is the primary function of a distributor?✓ Verified · Practice →
PYQ DiscoveryBrowse all verified PYQs
Open Index
Ready for exam mode?Practice this knowledge in Premium Mock Tests
Open Mock Tests →