Performance of Stress Grading Systems in an Aerospace Environment

With increasing environmental concerns, more electrical power is expected to be applied in future aircraft with a higher operation voltage level. All existing aircraft cables are unscreened cables that can withstand a relatively low voltage level. Therefore, screen cables are promising alternatives to withstand high voltage levels as it can avoid electric discharge in the air around the cable, while still managing insulation thickness effectively for weight control. However, the cable screen at the end of the cable has a sharp edge that causes a high electric field area. It can lead to partial discharge and permanent failure of insulation systems. Stress grading system is an effective method to control the electric field around the cable termination and has been widely used. However, there is limited information related to its applications in aerospace environments. The paper aims to investigate the feasibility of applying stress grading tapes at screened cable terminations for future aircraft. Partial discharge inception voltages at a cable termination were measured under aerospace conditions. Then the corresponding partial discharge inception electric fields were simulated based on finite element method. The results indicated that the application of stress grading system can increase partial discharge inception voltage up to 30% in an aerospace condition. Furthermore, partial discharge inception voltage is affected by frequency with a stress grading system, while it is stable without a stress grading system.