Atlas Copco GHS 730 VSD+ - Page 109

Instruction book
6996 0227 40 109
AWG or kcmil
Maximum current
10
< 30 A
8
< 50 A
6
< 65 A
4
< 85 A
3
< 100 A
2
< 115 A
1
< 130 A
1/0
< 150 A
2/0
< 175 A
3/0
< 200 A
Calculation method for UL:
 Single supply cables (3 phases + 1 PE - configuration (1)):
 Add 25% to the total current from the tables (see UL 508A 28.3.2: “Capacity shall have 125% of
the full load current”)
 Install the prescribed maximum fuse on each cable
 Parallel supply cable (2 x 3 phases + 2 PE - configuration (2)):
 Add 25% to the total current from the tables and divide by 2
 Multiply the capacity of the cables with 0.8 (see UL 508A table 28.1 continued)
 Install fuses of half the size of the recommended maximum fuse size on each cable.
 When using 2 x 3 phase + 2 PE as in (3):
 Add 25% to the total current from the tables and divide by √3
 Multiply the capacity of the cables with 0.8 (see UL 508A table 28.1 continued)
 Fuse size: the recommended maximum fuse size divided by √3 on each cable.
 Size PE cable:
 For supply cables up to AWG8: same size as the supply cables
 For supply cables larger than AWG8: use maximum allowed capacity.
< 100 A: use AWG8
< 200 A: use AWG6
< 300 A: use AWG4
Always check the voltage drop over the cable (less than 5 % of the nominal voltage is
recommended).Example of supply cable calculation: Itot= 128 A, maximum ambient temperature is 45
°C, recommended fuse = 150 A.
 Single supply cables (3 phases + 1 PE - configuration (1)):
 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
 Install the prescribed maximum fuse (150 A) on each cable
 Parallel supply cable (2 x 3 phases + 2 PE - configuration (2)):
 I = (128 A + 25%)/2 = (128 x 1.25)/2 = 80 A
 For an AWG4, the maximum current is 85 A x 0.8 = 68 A, which is insufficient. For an AWG3, the
maximum current is 100 x 0.8 = 80 A. So 2 parallel cables of 3 x AWG3 + 2 x AWG8 are sufficient.
 Install 80 A fuses on each cable.