Question

The losses in transmission lines are:
(A) Radiation losses only
(B) Conductor losses only
(C) Dielectric heating only
(D) All of the above

Answer 1

Hint: There are mainly two types of losses in transmission lines: technical losses and non-technical losses. In technical loss we have radiation loss, conductor loss, dielectric heating loss, coupling loss and corona loss. In case of non-technical losses there are power theft, metering inaccuracies, etc.

Complete step by step solution:
In a transmission line we face the following types of losses:
(i) Radiation loss: It happens when the distance between the conductors in the transmission line is comparable to the wavelength. In such cases the electromagnetic and electrostatic field of the conductors acts as small antennas which conducts out energy to the nearby conducting materials.
(ii) Conductor loss: Conductor losses are often called power loss. It is mainly due to the resistance of the conductor. Conductor also is also due to frequency which is known as skin effect. Skin effect is the tendency of the alternating current by which they tend to increase the current density near the surface more than that at the core i.e. the current appears to flow on the skin of the conductor.
(iii) Dielectric heating loss: Dielectric heating loss is due to the potential difference between the two conductors of a transmission line. When air is the dielectric, loss is negligible. However, in case of solid conductors it increases with the frequency.

Therefore, the correct answer here is option D (All of the above).

Note: Two more types of loss should be kept in mind i.e. coupling loss and corona loss. Coupling loss occurs when connection between two transmission lines are made. Corona is the luminous discharge that occurs between two transmission lines. It generally destroys the transmission line.