Hello student!!

The effect in which the voltage at the receiving end of the transmission line is more than the sending voltage is known as the Ferranti effect. Such type of effect mainly occurs because of light load or open circuit at the receiving end.

Ferranti effect is the increase in voltage occurring at the receiving end of a very long (> 200 km) AC electric power transmission line, relative to the voltage at the sending end, when the load is very small, or no load is connected.

The Ferranti effect is more pronounced the longer the line and the higher the voltage applied.The relative voltage rise is proportional to the square of the line length and the square of frequency.

The Ferranti effect is much more pronounced in underground cables, even in short lengths, because of their high capacitance per unit length, and lower electrical impedance.

The Ferranti effect is a phenomenon that describes the increase in voltage  that occurs at the receiving end of a long transmission line  relative to the voltage at the sending end. The Ferranti effect is more prevalent when the load is very small, or no load is connected (i.e. an open circuit). The Ferranti effect can be stated as a factor, or as a percent increase.

Ferranti Effect occurs when current drawn by the distributed capacitance of the line itself is greater than the current associated with the load at the receiving end of the line(during light or no load).

This capacitor charging current leads to a voltage drop across the line inductor  of the transmission system which is in phase with the sending end voltages. This voltage drop keeps on increasing additively as we move towards the load end of the line and subsequently, the receiving end voltage tends to get larger than applied voltage leading to the phenomena called Ferranti effect in power system .