• Install fuses which are smaller than or equal to the Max. fuse values from the technical
data sheets or instruction manual
• Size of the PE cable
• Use the maximum allowed ampacity of the selected supply cables and compare with
the value in the table below according to UL508A
Ampacity Size of PE
< 90 A 8 AWG
< 125 A 6 AWG
< 150 A 6 AWG
< 200 A 4 AWG
< 225 A 2 AWG
< 400 A 1/0 AWG
< 500 A 1/0 AWG
< 800 A 2/0 AWG
< 1000 A 3/0 AWG
Note: The above table has been prepared for user convenience. Only the latest editions of
the UL standard and its amendment(s) are to be considered as the official documents.
Always check the voltage drop over the cable (less than 5 % of the nominal voltage is
recommended).
Example of supply cable calculation
I
Package
= 128 A, maximum ambient temperature is 30 °C, maximum fuse = 200 A
• Single supply cables (3 phases + PE):
• I = 128 A + 25 % = 128 x 1.25 = 160 A
• For AWG2/0, the maximum current is 175 A, which is sufficient => use AWG2/0
• So use a cable of 3 x AWG2/0 + AWG4
• Parallel supply cable and phase supply cable 2 x (3 phases + PE):
• I = (128 A + 25 %)/√3 = (128 x 1.25)/√3 = 93 A
• For AWG3, the maximum current is 100 A, which is sufficient => use AWG3
• So use a cable of 2x (3 x AWG3 + AWG6)
• Parallel phase supply cable 4 x (3 phases + PE):
• I = (128 A + 25 %)/(√3 x 2) = (128 x 1.25)/(√3 x 2) = 47 A
• For AWG5, the maximum current is 50 A, which is sufficient => use AWG8
• So use a cable of 4x (3 x AWG8 + AWG8)
Cable connections
• Number of cables: 1x(3+PE) or 2x(3+PE)
• Cable type: Copper stranded wire 75/90°C stranded
• Wire size range:
UL/CSA variants
Instruction book
72 9829 3199 74
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