对笼型感应电动机供电的超灵敏瞬时故障保护

供电系统中的相间故障,可能会损坏设备,与引起火灾或爆炸;如果发生在石油化工厂或煤矿井下则更为危险。仅仅以电流大小来作为笼型感应电动机供电系统的短路保护,已不能完全令人满意。本文论述了一种具有理想特性的相间故障保护装置。

Investigation and Evaluation of Multilevel H-NPC Converter for Electrically Driven Trains

In this paper the operation of a three level H-bridge converter as well as its parallel operations is analyzed and simulated on the computer. Based on the simulation results the operating behavior between （a） a three level H-bridge neutral point clamped convener, （b） a three level back-to-back H-bridge neutral point clamped convener, （c） two three level H-bridge neutral point clamped converters parallel connected is being compared. From the simulation results it is obvious that in the first two cases the ripples, the distortion in primary and secondary winding currents, and the power factor are quite satisfactory and almost identical to each other. In the third case as compared with the first two, it is observed that current harmonics with higher amplitude appear in the primary winding of the transformer.

关于制作三路载波机的几点体会

电信工作以长途为网,在我国国民经济大跃进的高潮中,各地邮电工业部門大量研究和制造各式载波机,发展复用長途线路的多路通信系統,使邮电通信工作多、快、好、省地滿足党和国家的通信需要,为社会主义建设服务,为全国工农业继续大跃进服务,是当前的一項重要的政治任务。目前,三路载波机通信设备的应用日益普遍。因此本文所介紹的制作三路载波机的經驗,特別是其中理論和实际相结合来分析载频稳定度的問题,可作重要的参考。为了广泛交流制作载波机的经驗,本刊欢迎这样切合实际需要的文章,请各地邮电工业部門组织稿件,及时介绍推广。