The Pulse Width Modulation (PWM) inverter plays an important role in express locomotive. Especially after traction motors are fed by fast switching inverters, the interturn insulation is destroyed more heavily. However, a new type of polyimide corona resistant film is developed and used in insulation of traction motors. In order to investigate the service life of this kind of traction motor, the mechanism and characteristics of dielectric breakdown of polyimide corona resistant are studied in the paper. Experiments have been carried out on specimen according to the condition of traction motor. The breakdown point of tested sample film is analyzed through energy spectrum analysis and electron microscopic photograph. At last, it is presented that the characteristics and mechanism of breakdown of polyimide corona resistance film.

开发了一种基于3层CöS结构的电能量计费管理系统，该系统通过公用数据通信网将各电厂采集的电能量数据远程传输到控制中心，由控制中心进行计费、查询、生成报表、数据分析等处理，并以Web方式发布在Internet上供用户查询。详细介绍了系统的目标、结构、工作原理和功能，分析了3层CöS结构应用程序的优点和工作原理，并给出了采用Delphi实现这种3层CöS结构的方法。

The insulation on-line monitoring and fault diagnosis for high voltage power equipments is one of the most important techniques to maintain the reliability of power system. Since 1990s, the insulation on-line monitoring and fault diagnosis techniques have been greatly developed in China. Many universities, companies and research institutes have made great effort in this field. In this paper, the progress in China with the respects to partial discharge (PD) detection methods, on-line calibration, interference suppression, and fault diagnosis are reviewed.

青藏铁路格拉段是世界上海拔最高的高原铁路，雷击过电压保护面临高原和冻土两大难题。针对雷击过电压的影响因素,在分析格拉段雷暴活动情况及沿线高原冻土地区地质特点的基础上，提出铁路沿线防雷接地工程的实施办法。结合高原冻土地区的特点，探讨了格拉段防雷接地技术的新思路和急需解决的问题。