Measurement and analysis of the electric and magnetic field on a 22 kV woodpole distribution line

Summary

A device which measures the magnitude and phase of the fundamental component (50 Hz) and of the harmonics up to the 10th of the electric and magnetic fields was developed. The unit was installed on a 22 kV woodpole distribution line and measurements were compared to the power line real and reactive power flow and to the load power factor as well as to the prevailing weather conditions. The premise was that by measuring the electric and magnetic fields near a line it would be possible to derive information about the state of the line such as a conductor being dislodged from the insulator support and hanging low. The magnetic field measurements showed close correlation with the line phase current. It was expected that the measured electric field would be influenced by the position of the device relative to the conductors and ground, and would only vary due to the line voltage regulation. Contrary to this premise, the measured electric field changed significantly within hours or even some minutes. The cause for the unexpected electric field variations is explored by laboratory testing and the effect of certain modifications to the line test setup.

Additional informations

Authors

Freiburg Michael, Sun Haofei, Shimonosono, Albano Maurizio