42 Electrical design and installation
Manual Energy Storage Inverter ESI-S
Step 2: Using the cable section A, the cable material and the network frequency as entry
points in
, determine the multiplication factor X. For the DC current, the
multiplication factor X is equal to 1.
Table 19: Multiplication factors X for different cable sections
Cable section [mm²]
Network frequency 50Hz Network frequency 60 Hz
Al-cable Cu-cable Al-cable
Cu-cable
16
1.00
1.00
1.00
1.00
25
1.00
1.01
1.00
1.01
35
1.01
1.01
1.01
1.02
50
1.01
1.03
1.02
1.04
70
1.02
1.05
1.03
1.06
95
1.04
1.08
1.05
1.10
120
1.05
1.11
1.07
1.14
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:
ESI-S 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 ESI cable connection.
As an example of the cable sizing procedure, consider
and
, which show
the allowed current for different parameters noting typical cable manufacturer data.
