Electric-Field Analysis of Spacer Cable Systems for Compact Overhead Distribution Lines

Spacer cable systems (SCS) have been shown to be an appropriate solution to reduce the fault rates within wooden areas. Although the SCS are designed as a coordinated system with dielectric compatibility between materials, electrical tracking on the insulating materials has been reported once in operation. The problem of high electric-field concentration on the contact points between the covered conductor and spacer or ties cannot be controlled by modifying the material properties since the issue is more related to the zero-angle contact points. In this paper, 3-D finite-element modeling is used to compute the electric-field distribution on SCS. According to the simulation results, the electric-field enhancement seen around the seat area of the spacer is in contact with the cable and can be reduced to some degree by using materials with the same dielectric properties; however, even if the materials are compatible, an intense electric field on the area of contact is present. It is considered that instead of trying to find an exact match of the materials properties, the tracking resistance must be improved as much as possible in order to extend the service life of the system.