What is ferrantic effect?

Output voltage is greater than the input voltage or receiving end voltage is greater than the sending end voltage.

The Ferranti effect is a rise in voltage occurring at the receiving end of a long transmission line, relative to the voltage at the sending end, which occurs when the line is energized but there is a very light load or the load is disconnected.

This effect is due to the voltage drop across the line inductance (due to charging current) being in phase with the sending end voltages. Therefore both capacitance and inductance are responsible for producing this phenomenon.

The Ferranti Effect will be 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.

Due to high capacitance, the Ferranti effect is much more pronounced in underground cables, even in short lengths.