程控电话下井使用,对实现煤矿井下通讯现代化具有重要意义。为防止电火花引燃瓦斯和煤尘,井下通讯信号采用本质安全型——即把电能限制到不能引起瓦斯煤尘爆炸的程度。故程控电话下井,关键要解决两个问题:一是程控电话交换机对井下电话机的供电电源应 Program-controlled telephones to go down and use, to achieve the modernization of coal mine communications is of great significance. In order to prevent electric spark from igniting gas and coal dust, the underground communication signal adopts intrinsically safe type - that is, limiting the electric energy to such an extent that it can not cause gas and coal dust explosion. Therefore, the program-controlled telephone to go down, the key to solve two problems: First, program-controlled telephone switches underground power supply should be