Atlas Copco GA 45+

• Add 10 % to the total compressor current (I
tot
Pack or I
tot
FF from the tables) and divide
by 2
• Multiply the ampacity of the cables with 0.8 (see table A.52.17 (52-E1))
• Install fuses of half the size of the recommended maximum fuse size on each cable.
• When using 2 x 3 phases + PE as in (3):
• Add 10 % to the total compressor current (I
tot
Pack or I
tot
FF from the tables) and divide
by √3
• Multiply the ampacity of the cables with 0.8 (see table A.52.17 (52-E1))
• Fuse size: the recommended maximum fuse size divided by √3 on each cable.
• Size of the PE cable:
• For supply cables up to 35 mm²: same size as supply cables
• 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: I
tot
= 234 A, maximum ambient temperature is 45 °C, recommended fuse = 315 A
• Single supply cables (3 phases + PE - configuration (1)):
• I = 234 A + 10 % = 234 x 1.1 = 257.4 A
• The table for method F, 70 °C cable temperature and ambient temperature of 45
°C allows a maximum current of 323 A for a 185 mm² cable. So use a 3 x 185 mm²
+ 95 mm² cable.
• If the table for method F, 90 °C cable temperature and ambient temperature of 45
°C is used, 120 mm² is sufficient. So a single cable 3 x 120 mm² + 70 mm² is
sufficient .
• Parallel supply cable (2 x 3 phases + PE - configuration (2)):
• I = (234 A + 10 %)/2 = (234 x 1.1)/2 = 128.7 A
• Install 160 A fuses on each cable instead of 315 A.
• For a cable of 95 mm², method F, 70 °C cable temperature and ambient
temperature of 45 °C, the maximum current is 209 A x 0.8 = 167.2 A. So 2 parallel
cables of 3 x 95 mm² + 50 mm² are sufficient.
• For a cable of 95 mm², method F, 90 °C cable temperature and ambient
temperature of 45 °C, the maximum current is 233 A x 0.8 = 186.4 A. So 2 parallel
cables of 3 x 70 mm² + 35 mm² are sufficient.
11.3 Protection settings
Setting motor overload relay (F21)
Frequency
(Hz)
Voltage (V) GA 30 P
F21 (A)
GA 37
F21 (A)
GA 37 P
F21 (A)
GA 45
F21 (A)
GA 45 P
F21 (A)
IEC
50 200 88.3 96.5 96.5 123.2 128.3
50 400 42.6 48.7 48.7 59.1 61.6
60 200 88.3 96.5 96.5 123.2 128.3
60 220 80.3 87.7 87.7 112 116.6
60 230 76.8 83.9 83.9 107.1 111.6
60 380 44 52 52 63 66
60 440 39.7 45 46 56.5 58.5
Instruction book
2920 7109 51 165