Research on Insulation Problems of the Polymer Insulated Busbar with Tape Winding Insulation

The polymer insulated busbar is a new type of current carrying equipment which is being more and more widely used all over the world. The tape winding insulation polymer insulated busbar is one of the major types of this kind of equipment which uses winded PTFE or PET tape to form its insulation. This article aims to discuss its characteristic insulation problems caused by its insulation materials and structures. An FEA (finite element analysis) was introduced to calculate the electric field distribution in a typical insulation structure. The radial and axial electrical strengths of samples of PTFE and PET tape winding insulation with different winding tensions were tested. And finally, an experiment on a real size polymer insulated busbar with prefabricated defect to observe the propagation and development of the discharge failure between tape layers. The result reveals that, the dielectric strength of the surface between the tape layers is the key point of the insulation of the tape winding insulation polymer insulated busbar; and this strength is determined by the surface pressure. Thus, the electrical performances of the whole insulation are related more firmly with the insulated tape's mechanic strength rather than its dielectric strength. The propagation processes of the discharge between tape layers are also summarized. From this research, the methods to improve the performances of the tape winding insulation polymer insulated busbar and to detective the discharge between tape layers can be concluded.