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Performance analysis of medium transmission line is done ____
By reactance diagram
By symmetrical component analysis method
By neglecting line inductance
On per phase basis
On per phase basis
Transmission line performance analysis is consistently performed on a per-phase basis, assuming a balanced three-phase system. This allows the complex three-phase power network to be reduced to a single-phase equivalent circuit, simplifying calculations for voltage regulation and efficiency.
Transmission line performance analysis is consistently performed on a per-phase basis, assuming a balanced three-phase system. This allows the complex three-phase power network to be reduced to a single-phase equivalent circuit, simplifying calculations for voltage regulation and efficiency.
VLNтАЛ=3тАЛVLLтАЛтАЛ тАФ Relationship between line-to-line and line-to-neutral voltage
IlineтАЛ=IphaseтАЛ тАФ Current relationship in Star (Y) connected systems
In a balanced three-phase system, the currents in the three lines are equal in magnitude and displaced by 120┬░. By considering only one phase (the line conductor and the neutral/ground return), the nodal equations for voltage and current become much easier to solve using methods like nominal-T or nominal-╧А circuits for medium transmission lines.
Medium transmission lines have lengths typically between 80 km and 200 km.
Per-phase analysis assumes that the load and source are balanced.
Nominal-╧А and Nominal-T circuits are used to model distributed parameters as lumped parameters.
Total power is calculated as P3╧ХтАЛ=3├ЧVphтАЛ├ЧIphтАЛ├Чcos(╧Х).
Reduces complexity of solving three simultaneous differential equations.
Facilitates the use of ABCD parameters for two-port network analysis.
Cannot be used directly if the system is unbalanced.
Requires conversion from Line-Line voltage to Line-Neutral voltage.
Voltage regulation calculation
Efficiency calculation of transmission lines
Power flow studies
The use of reactance diagrams (Option A) is specifically for fault analysis (Short Circuit Studies).
Symmetrical component analysis (Option B) is exclusively used for analyzing unbalanced fault conditions.
Neglecting inductance (Option C) would make the performance analysis of any transmission line fundamentally inaccurate.
D is correct тАФ Performance analysis of medium transmission lines is simplified by converting the three-phase system into a per-phase equivalent circuit, assuming balanced operating conditions.
Always convert three-phase power ratings to per-phase values using VphтАЛ=VLтАЛ/3тАЛ before performing any circuit calculations.