Power Line Corona Rings Optimization

Pfisterer LAPP Sefag develops and manufactures insulators and fittings for worldwide use in power supply networks. In the design process of new silicon insulators for high power transmission lines, achieving a low enough electric field on the insulator surface is crucial in order to avoid damage due to corona discharges. Following a non-standard request from a customer who wanted to guarantee a lower electrical field than usually accepted, an optimization of the geometrical dimensions of conducting corona rings placed at the end of the insulator was required.

Solution
An electrostatic assumption was used with adapted maximum voltages. Since Electrostatic analyses are not included in the Mechanical module of Workbench, a 3D thermal static analysis was used with adapted units and material properties in order to calculate the electric field in the air and in the structure. The geometrical dimensions of the corona rings were parameterized and an iterative optimization procedure allowed a decrease of the maximum electric field value to a satisfying level.

Power Line Corona Rings Optimization
Electric field in the air surrounding the insulators and power line. The complete model included a total of 179 silicon shields for the two insulators.

A useful design to start experimental validation and production without extensive iterative prototyping. Increased knowledge about the influence of geometrical parameters on the electric field