Technical details System pro M compact®

Systempro M compact ®Technical detailsOVR Surge Protective DevicesSPDsCabling and installation of Surge Protective Devices in an electrical panel50 cm ruleRemember that a 10 kA lightning current passing through a 1 m length of cable generates1000 Volts. Equipment protected by a surge arrester is subjected to a voltageequal to the sum of the U pvoltage of the surge arrester, U dof its disconnector andthe sum of the inductive voltages of connecting cables (U1+U2+U3).It is therefore essential that the total length (L = L1+L2+L3) of the connecting cablesis as short as possible (0.50 m).If this length (L = L1 + L2+L3) exceeds 0.50m, it is necessary to carry out one of thefollowing:• Reduce this length by moving the connection terminals.• Choose a surge arrester with a lower U pvalue.• Install a second, coordinated surge arrester near the device to be protected so asto adapt the combined U pvalue to the impulse withstand of the equipment to beprotected.Wiring ring surfacesThe wires must be arranged in such a way that they are as close to each other as possible(see adjacent diagram) to avoid overvoltages induced by a ring surface between phases,the neutral and the PE conductor.Routing of clean cables and polluted cablesDuring installation, lay clean cables (protected) and polluted cables as shown in theadjacent diagrams.To avoid magnetic coupling between the different cable types (clean and polluted), it isstrongly advised that they are kept apart (> 30 cm) and if a crossing cannot be avoided,it should be at right angles (90°).U1U DU2U PU3➤➤ ➤➤➤➤L1L2L3➤➤LPolluted cables D > 30 cm ➤ Clean cables➤CleancableMaincircuitbreakerRingsurfaceSurgearrestercircuitbreakerTerminal / MCBCleancable➤D > 30 cm➤Feeder 1➤D < 30 cm➤11MCB / SPDSPD / Earth terminalEquipotential grounding:It is critical to check the earth equipotentiality of the various items of equipment.Feeder 2NoteThe cross-section of theconnecting cables is calculatedaccording to the local shortcircuitcurrent level (where thesurge arrester is installed). Itmust be equal to the crosssectionof the installation’supstream cables.The minimum cross-section forthe earth conductor is 4 mm 2 ifthere is not a lightning conductorand 10 mm 2 if there is a lightningconductor.11/86 ABB