The most common classification of overhead AC transmission lines is based on their length and operating voltage. This classification is crucial for understanding how to model and analyze their performance, as different lengths have different electrical characteristics. The three types are:

• Short transmission lines: Typically less than 80 km in length and operating at voltages below 20 kV. For these lines, the effects of capacitance are considered negligible due to their short length, and only resistance and inductance are significant.

• Medium Transmission Lines: Ranging from 80 km to 240 km in length with operating voltages between 20 kV and 100 kV. At this length, the capacitance of the line becomes a significant factor and must be accounted for in performance analysis.

• Long Transmission Lines: Longer than 240 km and operating at very high voltages, usually above 100 kV. For these lines, all four electrical parameters—resistance, inductance, capacitance, and conductance—are considered to be uniformly distributed along the entire length of the line for accurate analysis.