ABB PQFS Installation, Operation And Maintenance Instructions page 39

The multiplication factor X to be used depends on the cable material (e.g. copper
[Cu], aluminum [Al]) and on the base frequency of the network on which the filter will
be installed. For a given installation its value can be determined using the following
process:
Step 1: Determine in a conventional way (e.g. using cable manufacturer's tables) the
cable section A (mm²) for the RMS current Irms obtained in 1 above.
Step 2: Using the cable section A, the cable material and the network frequency as
entry points in Table 16, determine the multiplication factor X.
Table 16: Multiplication factors X for different cable sections
Cable section
[mm²]
16
25
35
50
70
95
120
Step 3: Determine in a conventional way the cable section A2 (mm²) for the current
rating found by multiplying Irms by X.
If the new cable section A2 is equal to the initially found cable section A, the right
cable section taking into account the skin effect has been found.
If the new cable section A2 is bigger than the initially found cable section A, steps 2
and 3 have to be repeated with the new values until the cable section A2 found is
equal to the cable section A.
Remark: during this process it may be found that more than one cable per phase is
needed. The process then has to be applied to each cable.
As an illustration of the cable sizing process consider the following example:
PQFS 60 A/50Hz, 3-wire connection, cable material: Cu (copper)
Step 1: IN = 60A à cable section = 16 [mm2]
Step 2: multiplication factor for a 16 [mm2] copper cable at 50 Hz = 1.00
Step 3: I = IN x 1.00 = 60A x 1.00 = 60 A
Step 4: I = 60A à cable section: 16 [mm2]
This section is equal to the section found in the previous step.
Conclusion: one copper cable of 16 [mm2] per phase is sufficient.
Remark: The cable sizing process discussed in point 2 above only takes into
account the skin effect. Any further derating due to local standards and/or
installation conditions (e.g. distance between cables, number of cables connected in
parallel ...) have to be taken into account by the company responsible for the PQF
cable connection.
Network frequency
50Hz
Al-cable Cu-cable
1.00 1.00
1.00 1.01
1.01 1.01
1.01 1.03
1.02 1.05
1.04 1.08
1.05 1.11
Manual Power Quality Filter PQFS ç Electrical design and installation 39
Network frequency 60
Hz
Al-cable Cu-cable
1.00 1.00
1.00 1.01
1.01 1.02
1.02 1.04
1.03 1.06
1.05 1.10
1.07 1.14