Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
By using bundled conductor, the critical voltage for formation of corona will
Increase
Decrease
Remain same
Unpredictable
Increase
The critical disruptive voltage for corona formation is directly proportional to the effective radius of the conductor. By using bundled conductors instead of a single conductor, the effective radius (Geometric Mean Radius) increases, which raises the voltage required to exceed the breakdown strength of air, thus increasing the critical disruptive voltage.
The critical disruptive voltage for corona formation is directly proportional to the effective radius of the conductor. By using bundled conductors instead of a single conductor, the effective radius (Geometric Mean Radius) increases, which raises the voltage required to exceed the breakdown strength of air, thus increasing the critical disruptive voltage.
VcтАЛ=g0тАЛ╬┤mrln(rDтАЛ) тАФ Critical disruptive voltage formula
reqтАЛ=nrтЛЕdnтИТ1тАЛ тАФ Effective radius of bundled conductors
Corona occurs when the surface voltage gradient of a conductor exceeds the dielectric strength of the surrounding air (approx. 30 kV/cm peak). For a single conductor, the electric field intensity E=rln(D/r)VтАЛ. By bundling multiple conductors, the effective radius r of the arrangement increases (calculated as the geometric mean of the distances), which reduces the surface potential gradient for a given voltage, thereby delaying the onset of corona.
Corona loss is reduced with bundled conductors due to higher critical voltage.
Bundling increases the effective surface area, reducing the maximum electric field stress.
Higher critical voltage leads to lower radio interference and audible noise.
This technique is standard practice in EHV (Extra High Voltage) and UHV (Ultra High Voltage) transmission lines.
Reduced corona loss
Increased power transmission capacity
Lower line inductance
Reduced radio interference
Increased wind loading on towers
Higher capital cost due to more hardware
Complex mechanical design
EHV transmission lines (400kV and above)
UHV transmission lines
The factor g0тАЛ represents the disruptive strength of air, typically 21.1 kV/cm (rms).
Option B (Decrease) is incorrect because an increase in effective radius reduces the surface voltage gradient, not increases it.
A is correct тАФ Using bundled conductors increases the effective radius of the line, which raises the critical disruptive voltage required to trigger corona discharge.
Always remember that in transmission lines, reducing the maximum surface potential gradient EmaxтАЛ is the primary goal for minimizing corona; bundling is the most effective way to achieve this geometrically.