Ferranti effect
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.[1]
The Ferranti Effect will be more pronounced the longer the line and the higher the voltage applied.[2] The relative voltage rise is proportional to the square of the line length.[3]
Due to high capacitance, the Ferranti effect is much more pronounced in underground cables, even in short lengths.
It was first observed during the installation of underground cables in Sebastian Ziani de Ferranti's 10,000 volt distribution system in 1887. [4]
[edit] References
- ^ Ferranti Effect handout, Kathmandu University (internet archive)
- ^ Line-Charging Current Interruption by HV and EHV Circuit Breakers, Carl-Ejnar Sölver, Ph. D. and Sérgio de A. Morais, M. Sc.
- ^ A Knowledge Base for Switching Surge Transients, A. I. Ibrahim and H. W. Dommel
- ^ J. F. Wilson ,Ferranti and the British Electrical Industry, 1864-1930, Manchester University Press, 1988 ISBN 0719023696 page 44
