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Consider the following statements:
1 ┬╖ By using bundle conductors in an overhead line, the corona loss is reduced.
2 ┬╖ By using bundle conductors, the inductance of transmission line increases and capacitance reduces.
3 ┬╖ Corona loss causes interference in adjoining communication lines ┬╖ Which of these statements are correct?
1 and 2
2 and 3
1 and 3
1, 2 and 3
1 and 3
Bundle conductors reduce the electric field intensity at the surface of the conductors by increasing the effective radius of the transmission line ┬╖ Since corona loss depends on the voltage gradient being higher than the critical disruptive voltage, increasing this radius effectively raises the critical voltage, thereby minimizing corona loss and associated interference.
Bundle conductors reduce the electric field intensity at the surface of the conductors by increasing the effective radius of the transmission line ┬╖ Since corona loss depends on the voltage gradient being higher than the critical disruptive voltage, increasing this radius effectively raises the critical voltage, thereby minimizing corona loss and associated interference.
L=2├Ч10тИТ7ln(GMRGMDтАЛ) тАФ Inductance per meter
C=ln(GMD/GMR)2╧А╧╡0тАЛтАЛ тАФ Capacitance per meter
The effective GMR (Geometric Mean Radius) of a bundled conductor is much larger than that of a single conductor ┬╖ As the effective radius ReffтАЛ=nrтЛЕdnтИТ1тАЛ increases, the inductance L=2├Ч10тИТ7ln(GMRGMDтАЛ) decreases, and the capacitance C=ln(GMD/GMR)2╧А╧╡0тАЛтАЛ increases, contrary to the claim in statement 2.
Corona loss is proportional to (f+25)drтАЛтАЛ(VтИТVcтАЛ)2
Bundle conductors increase the surge impedance loading (SIL) capacity of the line
Interference in communication circuits occurs due to the high-frequency harmonics generated by corona discharge
Reduction in corona loss and radio interference
Increased power transfer capability
Reduction in line inductance
Increased wind loading on towers
Complexity in design and installation
Higher costs due to additional hardware and spacers
Extra High Voltage (EHV) transmission lines
Ultra High Voltage (UHV) transmission lines
Statement 2 is incorrect because the use of bundle conductors actually increases the capacitance (due to larger effective diameter) and decreases the inductance.
Corona loss is often calculated using Peek's Law.
C is correct тАФ Bundle conductors decrease inductance and increase capacitance, while successfully reducing corona loss and communication interference.
Always remember that bundling increases the effective radius, which inversely affects L (decreases) and C (increases), a classic relationship tested in both Power Systems and EMFT.