Quincy Compressor QOFT 20 Instruction Book page 73

Instruction book
(1): Power distribution panel
(2): Compressor starter panel
Fuse calculations for cUL, CSA and UL: The indicated fuse size is the maximum fuse size in
order to protect the motor
Cable sizing according to UL
The table below indicates the current carrying capacities of cables for commonly used installation
methods, according to standard UL 508A. Ampacities of insulated conductors, copper 75°C.
AWG or kcmil
10
8
6
4
3
2
1
1/0
2/0
3/0
4/0
250
300
350
400
500
Note: The above table has been prepared for user convenience. Only the latest editions of the UL
standard and its amendment(s) are to be considered as the official documents.
Cable calculation method for UL
Calculation method according to UL 508A
• Single supply cables (3 phases + PE)::
• Add 25 % to the total package current (Package current from the technical data sheets)
• Install fuses on each supply cable which are smaller than or equal to the Max. fuse
values from the technical data sheets or instruction manual
• Connection between contactors must be made by means of copper bars
• Parallel supply cables and phase supply cables (2 x (3 phases + PE)):
• Add 25 % to the total package current (Package current from the technical data sheets)
and divide by √3
• Install fuses on each supply cable which are smaller than or equal to the Max. fuse
values from the technical data sheets or instruction manual
• Parallel phase supply cables (4 x (3 phases + PE)):
• Add 25 % to the total package current (Package current from the technical data sheets)
and divide by √3 and then by 2
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Ampacity
< 30 A
< 50 A
< 65 A
< 85 A
< 100 A
< 115 A
< 130 A
< 150 A
< 175 A
< 200 A
< 230 A
< 255 A
< 285 A
< 310 A
< 335 A
< 380 A
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