Neutral current estimation for multi-grounded concentric neutral cable system

Concentric neutral cable system is a most popular practice in distribution systems of North America. Because of the special structure of this type of cable, the concentric neutral conductor serves as a current-carrying conductor and the neutral current can´t be measured directly. The potential over loading of neutral conductor may result in cable over-heating. In order to understand the neutral current distribution along the cable, especially for multi-grounded neutral cable system, this paper presents a method to estimate the neutral current by the known three phase currents only. The impacts of each system parameters on the neutral current are also investigated.