contact protection and indirect protection is maintained after crash, the circuit is no harmful.安全电压...sufficiently low, the circuit is not harmful.人体保护physical protection =》物理保护(避免直接接触和间接接触)concept:if direct
芝加哥市区污水处理区metropolitan water reclamation district of greater chicago(mwrdgc)的工作任务:1、 确保该地区区民的饮水安全和健康;...西西南污水处理厂由西厂和西南厂合并而成,现称为司提克内水回收厂(stickney water reclamation plant),是一座具有90多年历史的污水处理厂西厂于1930年建成投入运行,为一座有