Proximity effect and Skin effect

The effective resistance of a conductor in transmission lines is increased by the proximity effect and skin effect. Let's understand each effect in detail:

1. Proximity effect:
The proximity effect is the phenomenon in which the distribution of current in a conductor is not uniform when multiple conductors are placed close to each other. When AC current flows through a conductor, it generates a magnetic field around it. This magnetic field induces eddy currents in adjacent conductors. These eddy currents create a counter magnetic field that opposes the original magnetic field, causing the current to concentrate near the surface of the conductor. As a result, the effective resistance of the conductor increases.

2. Skin effect:
The skin effect is another phenomenon that occurs in AC transmission lines. It is the tendency of AC current to flow more on the surface of a conductor rather than through its entire cross-section. This is due to the self-induced magnetic field generated by the current. The magnetic field creates a circulating eddy current in the conductor, which in turn generates an opposing magnetic field. This opposing magnetic field pushes the current towards the surface of the conductor, causing it to flow mostly near the outer surface. As a result, the effective resistance of the conductor increases.

Combined effect:
Both the proximity effect and skin effect cause the current to concentrate near the surface of the conductor. This results in an increased effective resistance. The increase in resistance leads to higher power losses in the transmission line and reduces the overall efficiency of the system.

Conclusion:
In transmission lines, the effective resistance of a conductor is increased by the combined effect of proximity and skin effects. These effects must be considered in the design and operation of transmission lines to minimize power losses and ensure efficient power transmission.