The correct answer is: C. Long transmission lines
Shunt capacitance is the capacitance between the conductors of a transmission line. It is usually neglected in the analysis of short transmission lines because its effect is small. However, for long transmission lines, shunt capacitance can have a significant effect on the line’s performance.
The reason why shunt capacitance is neglected in the analysis of short transmission lines is because the effect of the capacitance is small compared to the other effects, such as the resistance and inductance of the line. The capacitance of a transmission line is proportional to the length of the line, so for a short line, the capacitance is small.
However, for a long line, the capacitance can be significant. The capacitance of a transmission line is also proportional to the square of the voltage, so for a high-voltage line, the capacitance can be even more significant.
The effect of shunt capacitance is to reduce the effective resistance of the line. This is because the capacitance provides a path for current to flow that is in parallel with the resistance of the line. This means that less current flows through the resistance, and so the resistance has less of an effect on the line’s performance.
The effect of shunt capacitance is also to increase the effective inductance of the line. This is because the capacitance provides a path for current to flow that is in series with the inductance of the line. This means that more current flows through the inductance, and so the inductance has more of an effect on the line’s performance.
The effect of shunt capacitance can be significant for long transmission lines. It can reduce the effective resistance of the line and increase the effective inductance of the line. This can affect the line’s performance in a number of ways, such as by reducing the line’s power transfer capability and increasing the line’s losses.