Planning with SIVACON 8 PS - Siemens

Planning with BD2A/BD2C3.3 Technical data3.3.2 Tap-off unitsTypeBD2-AK2..., BD2-AK3...Rated current Ie 25 A 63 A 125 A 250 A 400 ASwitching capacity of the contact mechanism AC-22B – – – –Switching capacity of the built-in switch disconnector acc. toDIN EN 60947-3 at 400 VMax. permissible unrestricted rated short-circuit current when using tap boxeswith miniature circuit-breakers:– AC-22B AC-21B – –10 kArms: In the case of higher prospective short-circuit currents, "back-upprotection" must be implemented for the miniature circuit-breaker.25 kArms: Higher prospective short-circuit currents must be limited asfollows by the upstream protective device:• max. on-state energy I 2 t = 12 × 10 4 A 2 s;• max. on-state current ID = 9.5 kAImportant planning guidelineIt is not the case that every tap-off unit has a rated voltage of 690 V and a short-circuitresistance in accordance with the system size.The tap-off units used must be compatible with the values required by the equipment as faras their short-circuit resistance and rated voltage are concerned.If the tap-off unit is not compatible with the rated voltage, a unit with appropriate internalcomponents must be selected. Higher short-circuit currents must be limited by means ofupstream protection devices (e.g. circuit-breakers).Planning with SIVACON 8 PS62 Planning Manual, 10/2007, A5E01541101-01