Electrical Breakdown in High-Voltage Winding Insulations of Different Manufacturing Qualities

摘要

The results show that electrical tree propagation is the main electrical degradation mechanism that leads to breakdown of the main wall insulation, and that poor impregnation of the insulation and type of taping can reduce time to breakdown significantly. Due to an increasing demand for new, or the refurbishment of, power stations, high-voltage rotating machines continue to play a significant role in generating electrical energy. An important component of these machines is their electrical insulation. Although much research has been done to improve the material, about a quarter of all failures still are related to insulation problems. The state of the art of winding insulation is a composite of mica, binder resin, and a support material, the so called mica tapes. A peculiarity of the insulation is that the tapes are intermediate products, which usually are produced by a different company than the manufacturer of the final insulation or the entire machine. Such a discontinuity in the production process results in many different types of insulation systems and a variation in manufacturing quality.