Abstract: The mission of relay protection in the high voltage power supply line of factory is introduced．The basic requests for protection equipment are put forward，and the principle，characteristics and usages of the common relay protection method are discussed．

Key words: relay protection, breakdown, over-·current~single-·phase earthing

摘要： 介绍了在工厂高压供电线路中继电保护装置的作用；提出对保护装置的基本要求，对常用的继电保护方式的 原理、特点和使用进行探讨．

关键词: 继电保护, 故障, 过电流, 单相接地