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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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Bundled conductors are mainly used
To increase shunt capacitance
To decrease shunt capacitance
To increase series reactance
To decrease series reactance
To decrease series reactance
Bundled conductors, consisting of two or more conductors connected in parallel per phase, are primarily employed in EHV and UHV transmission lines to reduce series reactance and suppress corona discharge. By effectively increasing the Geometric Mean Radius (GMR) of the conductor bundle, the inductive reactance of the line is significantly lowered.
Bundled conductors, consisting of two or more conductors connected in parallel per phase, are primarily employed in EHV and UHV transmission lines to reduce series reactance and suppress corona discharge. By effectively increasing the Geometric Mean Radius (GMR) of the conductor bundle, the inductive reactance of the line is significantly lowered.
L=2×10°−7ln(GMRGMD) — Inductance per unit length
XL=2πfL — Series inductive reactance
The inductive reactance of a transmission line is given by XL=2πfL, where inductance L is proportional to ln(1/GMR). When conductors are bundled, the GMR increases, which causes the effective inductance (L) to decrease. Consequently, the reduction in inductance leads to a lower series reactance (XL), improving the power transfer capability of the transmission line.
Bundled conductors reduce corona loss and radio interference by lowering the surface voltage gradient.
The surge impedance loading (SIL) of the line increases as reactance decreases.
Bundled conductors lead to an increase in shunt capacitance (C), not a decrease, which helps in voltage regulation.
The number of conductors per bundle is chosen based on the voltage level (e.g., 2 for 400kV, 4 for 765kV).
Reduced line inductance (lower XL)
Increased line capacitance (higher C)
Reduced corona effect and power loss
Increased surge impedance loading
Increased wind loading on towers
Higher mechanical complexity and cost
Requirement for spacers and dampers
Extra High Voltage (EHV) transmission lines
Ultra High Voltage (UHV) transmission lines
Lines where surge impedance loading needs to be maximized
Option A is incorrect because bundling actually increases shunt capacitance due to the increased effective surface area.
Option B is incorrect because capacitance is proportional to ln(1/r), and the increase in effective radius during bundling increases capacitance.
The reduction in series reactance enhances the steady-state stability limit of the power system.
D is correct — Bundled conductors effectively increase the Geometric Mean Radius (GMR) of the line, which significantly reduces the line inductance and, consequently, the series inductive reactance.
Always remember: Bundling increases the effective radius, which increases Capacitance (C) and decreases Inductance (L). Since XL=ωL, XL decreases; since XC=1/(ωC), XC also decreases.