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Traveling voltage wave and current wave have the same wave forms and travel together along the transmission line at a velocity
Of sound
Of light
Slightly less than that of light
Slightly less than that of sound
Slightly less than that of light
Traveling waves on a transmission line propagate at a velocity determined by the medium's permittivity and permeability. Since overhead lines are mostly air-insulated, this velocity is very close to, but always slightly less than, the speed of light in a vacuum due to losses and the presence of the conductors.
Traveling waves on a transmission line propagate at a velocity determined by the medium's permittivity and permeability. Since overhead lines are mostly air-insulated, this velocity is very close to, but always slightly less than, the speed of light in a vacuum due to losses and the presence of the conductors.
v=LCтАЛ1тАЛ тАФ Velocity of electromagnetic wave in terms of line parameters
v=╬╝╧╡тАЛ1тАЛ тАФ Velocity of light in the transmission medium
The velocity of a traveling wave is given by v=LCтАЛ1тАЛ, where L and C are the inductance and capacitance per unit length. For an overhead line, LтЙИ╬╝0тАЛ2╧Аln(D/r)тАЛ and CтЙИln(D/r)2╧А╧╡0тАЛтАЛ. Combining these leads to v=╬╝0тАЛ╧╡0тАЛтАЛ1тАЛ=c, which is the speed of light. Real conductors and finite conductivity result in a velocity slightly lower than c.
The velocity of electromagnetic waves in a vacuum is cтЙИ3├Ч108 m/s.
For overhead lines, the velocity is approximately 95% to 99% of c.
For underground cables, the velocity is significantly lower due to the dielectric constant (epsilonrтАЛ) of the insulation, typically vтЙИ╧╡rтАЛтАЛcтАЛ.
Allows calculation of fault location using traveling wave protection relays.
Provides accurate timing for wave reflection analysis in power systems.
High velocity creates steep-fronted surges which can stress insulation.
Attenuation of the wave occurs as it travels, complicating signal recovery.
Fault location in long-distance high-voltage transmission lines.
Analysis of lightning surge propagation in substations.
The velocity in overhead lines is approximately 300 meters per microsecond.
Option B is incorrect because the velocity is affected by the permeability and permittivity of the surrounding medium, preventing it from equaling the absolute speed of light in a vacuum.
C is correct тАФ Traveling waves propagate at a velocity slightly less than the speed of light due to the characteristics of the transmission line medium.
Always remember that while overhead lines propagate near the speed of light, underground cables propagate much slower because their dielectric constant is much higher than that of air.