Instruction book
96
2920 7101 22
Maximum allowed current in function of the ambient temperature for installation method
F,conductor temperature 90°C
Ambient temperature
Cable section
30 °C
40 °C
45 °C
50 °C
55 °C
25 mm²
< 135 A
< 123 A
< 117 A
< 110 A
< 103 A
35 mm²
< 169 A
< 154 A
< 147 A
< 139 A
< 128 A
50 mm²
< 207 A
< 188 A
< 180 A
< 170 A
< 157 A
70 mm²
< 268 A
< 244 A
< 233 A
< 220 A
< 204 A
95 mm²
< 328 A
< 298 A
< 285 A
< 269 A
< 249 A
120 mm²
< 383 A
< 349 A
< 333 A
< 314 A
< 291 A
150 mm²
< 444 A
< 404 A
< 386 A
< 364 A
< 337 A
185 mm²
< 510 A
< 464 A
< 443 A
< 418 A
< 388 A
240 mm²
< 607 A
< 552 A
< 528 A
< 498 A
< 461 A
Calculation method for IEC:
• Single supply cables (3 PE - configuration (1)):
• Add 10 % to the total compressor current (I
tot
Pack or I
tot
FF from the tables)
• Install the prescribed fuse on each cable
• Parallel supply cable (2 x 3 PE - configuration (2)):
• 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 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
= 89 A, maximum ambient temperature is 45 °C, recommended fuse = 100 A
• Single supply cables (3 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 sufficient. (35 mm² for method F) => cable 3 x 50 mm² + 25
mm².
• Parallel supply cable (2 x 3 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.
Summary of Contents for QGS 40
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