Step 1: Collecting all the project data 1.3 Connection to the public power supply system The checklist describes the required features of the network (nominal data). These must be compared with the design data of the low-voltage switchgear assembly. For the planning of a switchgear assembly, the necessary rated values of the grid must be determined and specifi ed. 3. Connection to the public power supply system Main distribution board: Outgoing device: ______________________ Transformer: Rated power (kVA): _____________________ Impedance u k (%): 4 6 Rated voltage ________ V a.c. V d.c. ________ Hz _______________ Rated current (A): _______________ Conductor designation:
L1, L2, L3 N PE PEN Protection class: I II Incoming device: ______________________ Connection incoming: from top from bottom from left from right _______________ copper alumini with cable lug with terminal conductor single conductor cross section (mmІ):
____________ 12 Rated voltage of the feed in VAC a.c., Hz Grid system TN-C, TN-C-S, TN-S, TT, IT Protection class II, protection by protective insulation Rated current Infeed current (rated current transformer / upstream protective device) Determine I , see step 2, design of a distribution board, page 22 nA Short-circuit resistance Derive value from the size of the transformer or use the information from the local power supplier Example calculation see pages 20-21.
I cp I " K For detailed information about - determination of the rated current (I ) Page 22 nA - determination of the rated short-time withstand current (I ) Page 20-21 CW Overvoltage Overvoltage category III, IV Incoming cable connection Type of incoming cable Type of cable Type of connection