Protection Settings - Atlas Copco GA 75+ Instruction Book

• When using 2 x 3 phases + PE as in (3):
• Add 10 % to the total compressor current (I
• 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 = 89 A, maximum ambient temperature is 45 °C, recommended fuse = 100 A
tot
• Single supply cables (3 phases + PE - configuration (1)):
• I = 89 A + 10 % = 89 x 1.1 = 97.9 A
• The table for B2 and ambient temperature = 45 ° C allows a maximum current of 93 A for a 50 mm²
cable. For a cable of 70 mm², the maximum allowed current is 118 A, which is sufficient. Therefore,
use a 3 x 70 mm² + 35 mm² cable.
If method C is used, 50 mm² is suffficient. (35 mm² for method F) => cable 3 x 50 mm² + 25 mm².
• Parallel supply cable (2 x 3 phases + PE - configuration (2)):
• I = (89 A + 10 %)/2 = (89 x 1.1)/2 = 49 A
• For a cable of 25 mm², B2 at 45 °C, the maximum current is 63 A x 0.8 = 50.4 A. So 2 parallel cables
of 3 x 25 mm² + 25 mm² are sufficient.
• Install 50 A fuses on each cable instead of 100 A.

11.3 Protection settings

Setting motor overload relay (F21)
Frequency
(Hz)
IEC
50
50
60
60
60
60
60
60
Settings for fan motor overload protection (Q15)
Frequency
(Hz)
IEC
50
50
60
192
Voltage (V) GA 55
F21 (A)
200 143
400 70.3
200 143
220 130
230 124.3
380 75.1
440 67.3
460 64.4
Voltage (V) GA 55
Q15 (A)
200 10.6
400 5.3
200 11.6
Pack or I FF from the tables) and divide by √3
tot tot
GA 55 P GA 75
F21 (A) F21 (A)
149 192
75.0 95.1
149 149
135.5 174.5
129.6 137
78.3 100.3
70.2 85.1
67.1 81.4
GA 55 P GA 75
Q15 (A) Q15 (A)
10.6 10.6
5.3 5.3
11.6 11.6
Instruction book
GA 75 P GA 90
F21 (A) F21 (A)
192 239
95.1 113.7
149 239
174.5 217.3
167 207.8
100.3 121.2
85.1 103.1
81.4 98.6
GA 75 P GA 90
Q15 (A) Q15 (A)
10.6 15.4
5.3 7.7
11.6 16.5
2920 7109 60