The main advantages of a High Transmission Line are the following: The transmission of electric power is carried at high voltages due to the following reasons
(i) Reduces the volume of conductor material:
Consider the transmission of electric power by a three-phase line.
Let P = power transmitted in watts
V = line voltage in volts
cosφ = power factor of the load
l = length of the line in meters
R = resistance per conductor in ohms
p= resistivity of conductor material
a = area of X-section of conductor
we know that current = power/voltage
resistance per conductor is given by,
we know that total power loss is a multiplication of the square of current and resistance, therefore,
now we have to determine the cross-section area of the conductor which is given by,
the volume of the conductor is the multiplication of area and length, which is given by,
From the above equation, it is clear that the for a given power, power loss, length, and resistivity, the volume of conductor material required is inversely proportional to the square of transmission voltage and power factor. In other words, the greater the transmission voltage, the lesser the conductor material required.
(ii) Increases transmission efficiency
Assuming J to be the current density of the conductor, then,
Now input power is given by
We know that transmission efficiency is given by the ratio of output power to the input power which is given by,
(iii) Decreases percentage line drop
