... devie (in short :SPD, alias:surge protector , surge arrester ) is suitable for TN-S,TN-C-S,TT,TI etc power supply system of AC ... device separate from the power system and give the indication signal , green meas normal , red means abnormal, Kevin wiring mode , ... electric network automatically , at the same time giving the indication signal . Visual window shows white for normal working and it shows ...