• Add 25 % to the total current from the tables (see UL 508A 28.3.2: "Ampacity 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 ampacity 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 ampacity 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 ampacity of the selected supply
cables and compare with value in table below (see CEC Part 1 table 17)
< 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: I
tot
= 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 a 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.
10.3 Protection settings
Setting motor overload relay (F21)
Frequency (Hz) Voltage (V) 30kW F21 (A) 37kW F21 (A) 45kW F21 (A)
IEC
50 230 73 84 104
60 230 75 85 106
60 380 45 53 64
50 400 42 50 60
60 460 37 44 53
50 500 34 39 48
UL/cUL
Instruction book
2920 7180 30 173
To Next Page
Loading...
