Section VIII - Technical data
Calculation method for IEC:
• Single supply cables (3 phases + PE - conguration (1)):
• Add 10% to the total vacuum pump current (Itot from the tables)
• Install the prescribed fuse on each cable
• Parallel supply cable (2 x 3 phases + PE - conguration (2)):
• Add 10% to the total vacuum pump current (Itot 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 vacuum pump current (Itot 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: Itot= 89 A, maximum ambient temperature is 45 °C, recommended fuse
= 100 A
• Single supply cables (3 phases + PE - conguration (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 sufcient. Therefore, use a 3 x 70 mm² + 35 mm² cable.
If method C is used, 50 mm² is sufcient. (35 mm² for method F) =>cable 3 x 50
mm² + 25 mm².
• Parallel supply cable (2 x 3 phases + PE - conguration (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 sufcient.
• Install 50 A fuses on each cable instead of 100 A.
Quincy Vacuum Pump-QSV Series 101
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