Ferranti effect

In electrical engineering, the Ferranti effect is an increase in voltage occurring at the receiving end of a long transmission line, above the voltage at the sending end. This occurs when the line is energized, but there is a very light load or the load is disconnected. The capacitive line charging current produces a voltage drop across the line inductance that is in-phase with the sending end voltages considering the line resistance as negligible. Therefore both line inductance and capacitance are responsible for this phenomenon.[1]

Illustration of the Ferranti Effect; addition of voltages across the line inductance

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]

The Ferranti effect is much more pronounced in underground cables, even in short lengths, because of their high capacitance.

It was first observed during the installation of underground cables in Sebastian Ziani de Ferranti's 10,000 volt distribution system in 1887.[4]

References

  1. ↑ Ferranti Effect handout, Kathmandu University (internet archive)
  2. ↑ Line-Charging Current Interruption by HV and EHV Circuit Breakers, Carl-Ejnar Sölver, Ph. D. and Sérgio de A. Morais, M. Sc.
  3. ↑ A Knowledge Base for Switching Surge Transients, A. I. Ibrahim and H. W. Dommel
  4. ↑ J. F. Wilson, Ferranti and the British Electrical Industry, 1864-1930, Manchester University Press, 1988 ISBN 0-7190-2369-6 page 44
This article is issued from Wikipedia - version of the Tuesday, May 03, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.