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Series inductance and series resistance of medium transmission lines are taken as:
Distributed and Lumped
Lumped and Distributed
Distributed
Lumped
Lumped
In medium transmission lines (typically ranging from 80 km to 250 km), the parameters of resistance and inductance are assumed to be concentrated or 'lumped' at specific points along the line. This simplification allows for easier mathematical modeling using T-network or ╧А-network representations instead of complex distributed parameter differential equations.
In medium transmission lines (typically ranging from 80 km to 250 km), the parameters of resistance and inductance are assumed to be concentrated or 'lumped' at specific points along the line. This simplification allows for easier mathematical modeling using T-network or ╧А-network representations instead of complex distributed parameter differential equations.
Z=R+j╧ЙL тАФ Series impedance per phase
Y=G+j╧ЙC тАФ Shunt admittance per phase
The transmission line is treated as a lumped-parameter circuit because the line length is relatively small compared to the wavelength of the power frequency (50/60 Hz). By concentrating the series impedance (R+j╧ЙL) and shunt admittance (G+j╧ЙC), we can use standard circuit analysis techniques like Kirchhoff's laws to solve for the sending and receiving end voltages and currents.
Medium lines use the ╧А (Pi) or T-model for analysis.
Distributed parameters are used for long lines (above 250 km) where wave propagation effects become significant.
Lumping parameters simplifies the calculation of voltage regulation and efficiency.
Shunt admittance in medium lines is also lumped at the ends or the center of the line.
Simplifies analytical calculations.
Provides sufficient accuracy for medium-length lines.
Avoids complex hyperbolic function calculations required for distributed lines.
Less accurate than the distributed parameter model.
Cannot account for phase shifts along the line length correctly for very long lines.
Power system analysis for sub-transmission systems.
Load flow studies for regional grids.
| Feature | Short Line | Medium Line |
|---|---|---|
Line Length | < 80 km | 80 - 250 km |
For short transmission lines (< 80 km), shunt capacitance is neglected entirely and series impedance is lumped.
Option A is incorrect because distributed parameters are reserved for long lines where wave phenomenon dominates.
D is correct тАФ For medium transmission lines, the resistance and inductance are treated as lumped parameters to simplify circuit analysis.
Always remember: Short lines neglect capacitance, medium lines use lumped parameters, and long lines require the Rigorous Solution using distributed parameters and hyperbolic functions.