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Self GMD method is used to evaluate
Inductance of the overhead transmission lines
Capacitance of the overhead transmission lines
Inductance and capacitance both of the overhead transmission lines
None of above
Inductance of the overhead transmission lines
The Self Geometric Mean Distance (Self GMD), often referred to as the Geometric Mean Radius (GMR) or DsтАЛ, is a fundamental parameter used to calculate the internal inductance of a conductor ┬╖ It accounts for the internal flux linkages of a conductor by representing the effective radius of an equivalent hollow conductor with no internal flux.
The Self Geometric Mean Distance (Self GMD), often referred to as the Geometric Mean Radius (GMR) or DsтАЛ, is a fundamental parameter used to calculate the internal inductance of a conductor ┬╖ It accounts for the internal flux linkages of a conductor by representing the effective radius of an equivalent hollow conductor with no internal flux.
L=2├Ч10тИТ7ln(DsтАЛGMDтАЛ)┬аH/m тАФ Calculation of inductance using GMD and Self GMD
DsтАЛ=reтИТ1/4тЙИ0.7788r тАФ Self GMD (GMR) for a solid cylindrical conductor of radius r
Inductance calculation involves two components: internal and external flux linkages ┬╖ By replacing the physical conductor with an equivalent one having a radius DsтАЛ (where DsтАЛ=rтА▓=reтИТ1/4 for a solid round conductor), the internal flux linkage is mathematically simplified to zero, allowing the total inductance to be calculated using external inductance formulas solely based on the geometric distances between conductors.
Self GMD (DsтАЛ) is strictly a parameter for inductance calculation, not capacitance.
For capacitance calculation, the actual physical radius (r) is used instead of the GMR (DsтАЛ), because there is no internal electric flux.
It simplifies the complex analysis of flux linkages within stranded or bundled conductors.
The value of DsтАЛ depends on the physical geometry and arrangement of conductor strands.
Simplifies calculation of transmission line parameters for bundled conductors.
Provides a unified method to handle internal flux linkage mathematically.
Does not apply to capacitance calculations.
Requires knowledge of specific conductor strand geometry for bundled configurations.
Power system transmission line modeling.
Calculation of steady-state stability parameters.
The factor eтИТ1/4 arises from the integration of magnetic flux density inside a circular conductor.
Option B is incorrect because capacitance calculation uses the physical radius r, as potential is uniform across the cross-section of the conductor.
A is correct тАФ Self GMD is used to account for internal flux linkages when determining the inductance of overhead transmission lines.
Always remember: use GMR (Self GMD) for inductance (because of internal flux) and use physical radius (r) for capacitance (because of charge distribution on the surface).