The transmission lines and the distribution lines themselves

The transmission lines and the distribution lines themselves are but conductors safely separated from each other and safely elevated above the ground in accordance with the National Electrical Safety Code (nesc). The electrical capacity of these lines is determined by their ability to transport apparent power. From a physical standpoint only, what are the limitations to the ability of these lines to transport this electrical power? Hint: There are quite a few.

Solution

The first limitation is the electrical resistance of the line. As the length of the line increases, the electrical resistance increases, and hence the power lost due to this resistance increases. This power loss limits the length of the transmission and distribution lines.

The second limitation is the voltage drop, which increases as the transmission line length increases.

The reliable capacity of the transmission line is made less than its physical or thermal limit to ensure reliability in case of failure of the other part of the network.