Electric Field and Potential Distribution in a 420 kV Novel Unibody Composite Cross-Arm

The use of uni-body composite cross-arm in a fully composite-based pylon is a new concept for the next generation of overhead transmission lines. The cross-arm is stressed by phase-to-phase voltages except in two regions, which are stressed by phase-to-ground voltages caused by installation of shield wires. Due to a major difference between the novel cross-arm structure and traditional composite cross-arms, the electric field distribution in the uni-body composite cross-arm is of considerable interest. This paper presents and analyses the electric field distribution around and inside the hollow core uni-body cross-arm through which ground cable passes to connect the shield wires. Two different shed profiles are considered on the cross-arm and evaluated based on the guidelines of IEC 60815-3.
The 2D geometry of pylon is modeled in ANSYS Finite Element Analysis package. The electric field and potential distribution along the pylon is graphically depicted and the effectiveness of assigned shed profiles in controlling the power frequency stresses are investigated in the areas with high field intensities.