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What is the transmission line voltage for different lengths of line?
132 kV for 120 km
220 kV for 200 km
400 kV for 300 km
All of these
All of these
In power systems, the selection of transmission voltage level is primarily governed by the transmission distance and the power to be transferred. As a rule of thumb, higher voltages are used for longer distances to reduce I2R losses, voltage drop, and conductor material requirements, making all listed pairings technically acceptable for practical overhead transmission lines.
In power systems, the selection of transmission voltage level is primarily governed by the transmission distance and the power to be transferred. As a rule of thumb, higher voltages are used for longer distances to reduce I2R losses, voltage drop, and conductor material requirements, making all listed pairings technically acceptable for practical overhead transmission lines.
VkVтАЛтЙИ5.50.62L+150PтАЛтАЛ тАФ Empirical relation for transmission voltage
PlossтАЛ=3I2R тАФ Power loss in three-phase transmission line
The relationship between line length and voltage is governed by Still's law, which suggests that the transmission voltage (VkVтАЛ) is approximately proportional to the distance of transmission (LkmтАЛ). Mathematically, VkVтАЛтЙИ5.5├Ч0.62L+150PтАЛтАЛ, where P is the power in MW; this ensures efficient power flow and maintains voltage regulation within statutory limits.
Higher voltage reduces the cross-sectional area of the conductor required for a given power.
Transmission lines are classified based on length: Short (<80 km), Medium (80-200 km), and Long (>200 km).
400 kV lines are typically used for long-distance bulk power transmission to maintain stability.
Voltage levels are standardized globally to ensure equipment interoperability.
Higher voltage reduces I2R power losses.
Lower voltage drop improves voltage regulation.
Higher voltage requires taller towers and increased insulation clearance.
Increased corona discharge losses at extra high voltages.
132 kV: Sub-transmission or medium distance transmission.
220 kV: Regional grid interconnections.
400 kV: Long-distance high-voltage backbone (EHV transmission).
The thumb rule for voltage selection is roughly 1 kV per kilometer of transmission distance as a rough estimate for HV lines.
Option D is correct because all mentioned pairings are standard industry configurations for transmission systems.
D is correct тАФ All the provided options represent standard transmission line voltage levels corresponding to their respective transmission lengths.
Always remember that increasing the transmission voltage by a factor of n reduces the required conductor cross-section by n2 for the same power loss and distance.