Ferranti effect

In electrical engineering, the 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.

It was first observed during the installation of underground cables in Sebastian Ziani de Ferranti's 10,000-volt AC power distribution system in 1887.

Therefore, both line inductance and capacitance are responsible for this phenomenon.

The Ferranti effect is more pronounced the longer the line and the higher the voltage applied.

[3] 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.

An equivalent to the Ferranti effect occurs when inductive current flows through a series capacitance.