Ferranti Effect on:
[Wikipedia]
[Google]
[Amazon]
In A Knowledge Base for Switching Surge Transients, A. I. Ibrahim and H. W. Dommel
The Ferranti effect is much more pronounced in underground cables, even in short lengths, because of their high capacitance per unit length, and lower
In electrical engineering
Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems that use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the l ...
, the Ferranti effect is the increase in voltage occurring at the receiving end of a very long (> 200 km) AC electric power transmission
Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines that facilitate this movement form a ''transmission network''. This is ...
line, relative to the voltage at the sending end, when the load is very small, or no load is connected. It can be stated as a factor, or as a percent increase.
It was first observed during the installation of underground cables in Sebastian Ziani de Ferranti
Sebastian Pietro Innocenzo Adhemar Ziani de Ferranti (9 April 1864 – 13 January 1930) was a British electrical engineer and inventor who pioneered high-voltage AC power in the UK, patented the Ferranti dynamo and designed Deptford power stat ...
's 10,000-volt AC power distribution system in 1887.
The capacitive line charging current produces a voltage drop across the line inductance that is in-phase with the sending-end voltage, assuming negligible line resistance. Therefore, both line inductance and capacitance are responsible for this phenomenon. This can be analysed by considering the line as a transmission line
In electrical engineering, a transmission line is a specialized cable or other structure designed to conduct electromagnetic waves in a contained manner. The term applies when the conductors are long enough that the wave nature of the transmis ...
where the source impedance is lower than the load impedance (unterminated). The effect is similar to an electrically short version of the quarter-wave impedance transformer, but with smaller voltage transformation.
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
In electrical engineering, impedance is the opposition to alternating current presented by the combined effect of Electrical_resistance, resistance and Electrical_reactance, reactance in a electrical circuit, circuit.
Quantitatively, the impedan ...
.
An equivalent to the Ferranti effect occurs when inductive current flows through a series capacitance. Indeed, a lagging current flowing through a impedance results in a voltage difference , hence in increased voltage on the receiving side.
See also
*LC circuit
An LC circuit, also called a resonant circuit, tank circuit, or tuned circuit, is an electric circuit consisting of an inductor, represented by the letter L, and a capacitor, represented by the letter C, connected together. The circuit can act ...
"A series resonant circuit provides voltage magnification."
*Reflections of signals on conducting lines
A signal travelling along an electrical transmission line will be partly, or wholly, reflection (physics), reflected back in the opposite direction when the travelling signal encounters a discontinuity (mathematics), discontinuity in the charact ...
* Failure of the first trans-Atlantic telegraph cable
*Telegrapher's equations
The telegrapher's equations (or telegraph equations) are a set of two coupled, linear partial differential equations that model voltage and current along a linear electrical transmission line. The equations are important because they allow trans ...
* Characteristic impedance#Transmission line model
References
{{Reflist Electric power transmission Electrical phenomena Ferranti Transmission lines