Transfer characteristics of electric-power lines passing through urban and suburban areas

• Series impedance of power lines passing through urban and suburban areas.
• Influence of urban metal installations on electric power lines characteristics.
• Influence of urban and suburban conditions on electric power line characteristics.

Distribution systems consist of single-phase, two-phase, and/or untransposed three-phase lines serving unbalanced loads. Because of that during normal operating conditions of a distribution line, unbalanced currents flow through the ground and neutral conductor(s). Also, a fluctuating magnetic field exists around and along the line and it interacts with the surrounding metal installations. Currents induced in these installations reduce the part of the current returning through the ground and neutral line conductor(s). Thus, for determination of the actual values of series impedance of distribution lines it is necessary to take into account the existence of surrounding metal installations. Independent of their basic function, these installations spontaneously form a large network of different mutually connected elements that are in direct or indirect contact with earth. Also, this network is mainly under the surface of the earth and it has structure and topology that cannot be visually determined or verified. However, from the standpoint of the influence on distribution line parameters all these, known and unknown, metal installations can be substituted by only one equivalent conductor. The favorable effects of this conductor on the series impedance of different types of distribution lines are evaluated.