Screening Factor of Pipe-Type Cable Systems

After reviewing the background of zero sequence impedance of pipe-type cables, the paper describes in general the longitudinal voltages induced in adjacent auxiliary cables due to a fault in power transmission systems. The magnitude of the induced voltage is influenced by the screening effect of the power cables. The screening factor and the impedance of the steel pipe have been measured in the laboratory by short-circuit tests on a 275-kV cable sample with a simulated ground return path. The results are used to illustrate the application in induced voltage calculations in a typical example.