Technical details System pro M compact®

Systempro M compact ®Technical detailsOVR Surge Protective DevicesSPDsCommon mode and/or differential mode protectionCommon modeCommon mode overvoltages appear between the live conductors and earth, e.g. phase/earth orneutral/earth.A live conductor not only refers to the phase conductors but also to the neutral conductor.This overvoltage mode destroys equipment connected to earth (class I equipment) and also equipmentnot connected to earth (class II equipment) which is located near an earthed mass and which doesnot have suffi cient electrical isolation (a few kilovolts).Class II equipment not located near an earthed mass is theoretically protected from this type ofattack.PhNI mcNote:Common modeovervoltages affectall earthing systems.UDifferential modeDifferential mode overvoltages circulate between live conductors: phase/phase or phase/neutral.These overvoltages have a potentially high damaging effect for all equipment connected to theelectrical network, especially ‘sensitive’ equipment.PhNNote:Differential mode overvoltages affectthe TT earthing system.These overvoltages also affectthe TN-S earthing system if thereis a considerabledifference in thelengths of theneutral cable and theprotective cable (PE).I md11ABB11/81