Ferranti Effect refers to a phenomenon in long transmission wherein the receiving end voltage is higher than the voltage at the sending end. The line capacitance in long transmission lines cause the higher voltage at the receiving end. The Ferranti Effect is more pronounced when the transmission line is lightly loaded eg. at night.
A transmission line draws a charging current from the current source. This charging current causes a voltage drop due to line inductance which is in series. This voltage drop is in phase opposition to the voltage at the receiving end. Thus, it causes the voltage at the sending end to drop lower than the receiving end.
The Ferranti effect can also be observed in cables based transmission systems. The effect is more in cables even for shorter lengths as cables have higher capacitances.