【通信应用笔记】在电信设备的环保理念 AN579 APPLICATION NOTE PROTECTION CONCEPTS IN TELECOMMUNICATIONS EQUIPMENT INTRODUCTION The goal of a telecommunication network (see Figure 1) is to permit data exchange (speech or digital) be- tween two or more subscribers. The network is made up of different parts which are subject to various disturbances. The most susceptible elements are the lines, due to their length and their geographical location. Disturbances strike the lines and are then propagated to the extremities of the lines at which lie telephone sets and the subscriber line interface cards (SLIC). So the lines receive two kinds of overv……