Guidelines for planning the electrical installation 53Optional du/dt filters protect motor insulation system and reduce bearing currents. Optionalcommon mode filters mainly reduce bearing currents. Insulated N-end (non-drive end)bearings protect the motor bearings. Requirements tableThe following table shows how to select the motor insulation system and when optionalABB du/dt filters, insulated N-end (non-drive end) motor bearings and ABB common modefilters are required. Failure of the motor to fulfil the following requirements or improperinstallation may shorten motor life or damage the motor bearings and voids the warranty.MotortypeNominal AC supplyvoltageRequirement forMotorinsulationsystemABB du/dt and common mode filters, insulated N-endmotor bearings100 kW < PN < 350 kWorIEC 315 < frame size <IEC 400PN > 350 kWorframe size > IEC 400ABB motorsRandom-woundM2_,M3_ andM4_UN < 500 V Standard + N + N + CMFForm-woundHX_ andAM_380 V < UN < 690 V Standard + N + CMF PN < 500 kW:+N + CMFPN > 500 kW+N + du/dt + CMFOld*form-woundHX_ andmodular380 V < UN < 690 V Check withthe motormanufacturer.+ N + du/dt with voltages over 500 V + CMFRandom-woundHX_ andAM_ **0 V < UN < 500 V Enamelledwire with fiberglass taping+ N + CMFHDP Consult the motor manufacturer.* manufactured before 1.1.1998** For motors manufactured before 1.1.1998, check for additional instructions with the motor manufacturer.Non-ABB motorsRandom-woundandform-woundUN < 420 V Standard:ÛLL = 1300 V+ N or CMF + N + CMF420 V < UN < 500 V Standard:ÛLL = 1300 V+ du/dt + (N or CMF) + N + du/dt + CMForReinforced:ÛLL = 1600 V,0.2microsecondrise time+ N or CMF + N + CMF
