Section VIII - Technical data
Cable sizing according UL/cUL
Calculation method according UL 508A, table 28.1 column 5: allowable ampacities of
insulated copper conductors (75 °C (167 °F)).
Maximum allowed current in function of the wire size
Calculation method for UL:
• Single supply cables (3 phases + 1 PE - conguration (1)):
• Add 25% to the total current from the tables (see UL 508A 28.3.2: “Capacity 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 - conguration (2)):
• Add 25% to the total current from the tables and divide by 2
• Multiply the capacity 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 capacity 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 capacity
< 100 A: use AWG8
< 200 A: use AWG6
Always check the voltage drop over the cable (less than 5 % of the nominal voltage is
recommended).
Example of supply cable calculation: Itot= 128 A, maximum ambient temperature is 45
°C, recommended fuse = 150 A
• Single supply cables (3 phases + 1 PE - conguration (1)):
102 Quincy Vacuum Pump-QSV Series
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