Cable section 30 °C 40 °C 45 °C 50 °C 55 °C
150 mm² < 444 A < 404 A < 386 A < 364 A < 337 A
185 mm² < 510 A < 464 A < 443 A < 418 A < 388 A
240 mm² < 607 A < 552 A < 528 A < 498 A < 461 A
300 mm² < 703 A < 639 A < 611 A < 576 A < 534 A
400 mm² < 823 A < 749 A < 716 A < 674 A < 625 A
Cable calculation method for IEC
•
Single supply cables (3 phases + PE):
• Add 10 % to the total package current (Package current from the technical data
sheets).
• Install fuses on each supply cable which are smaller than or equal to the Max. fuse
values from the technical data sheets or the instruction manual.
• Connection between contactors must be made by means of copper bars.
• Parallel supply cables (2 x (3 phases + PE)):
• Add 10 % to the total package current (Package current from the technical data sheets)
and divide by 2.
• Multiply the ampacity of the cables with the reduction factors per table B.52.17 of IEC
60364-5-52 (Method E or F), (typically 0.8).
• Install fuses which are smaller than or equal to the Max. fuse values of the technical
data sheets or the instruction manual.
• Size of the PE cable:
• For supply cables up to 16 mm²: same size as supply cables.
• For supply cables between 16 mm² and 35 mm²: 16 mm².
• For supply cables larger than 35 mm²: half the size of the supply wires.
Always check the voltage drop over the cable (less than 5 % of the nominal voltage is
recommended).
Example of supply cable calculation
Itot = 407 A, maximum ambient temperature is 45 °C, recommended fuse = 500 A.
• Single supply cables (3 phases + PE):
• I = 407 A + 10 % = 407 x 1.1 = 447.7 A
The table for method E (multi-core cable), 90 °C cable temperature and ambient
temperature of 45 °C allows a maximum current of 468 A for a 240 mm² cable. So use a
multi-core cable of 3 x 240 mm² + 120 mm².
• Parallel supply cable 2 x (3 phases + PE):
• I = (407 A + 10 %)/2 = (407 x 1.1)/2 = 224 A
For a single-core cable of 95 mm², method F, 90 °C cable temperature and ambient
temperature of 45°C, the maximum current is 285 A x 0.8 = 228 A. So two (2) parallel
(single-core) cables of 3 x 95 mm² + 50 mm² are sufficient.
For a multi-core cable of 95 mm², method E, 90 °C cable temperature and ambient
temperature of 45°C, the maximum current is 259 A x 0.8 = 207 A. This 95 mm² cable
would be too small, so you need to install a cable with a bigger section.
Looking at a multi-core cable of 120 mm², method E, 90 °C cable temperature and
ambient temperature of 45°C, the maximum current is 301 A x 0.8 = 240 A. The right
selection in this case would then be two (2) parallel cables of 3 x 120 mm² + 70 mm³.
Instruction book
9829 3178 63 67
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