SMA SUNNY ISLAND SIC40-MPT, Technical Description

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Electrical Connection SMA Solar Technology AG
20 SIC40-TEN081110 Technical Description
5.2.2 Grounding the Battery and the PV System
Cross-section of the Grounding Conductor
SMA Technologie AG cannot calculate generally valid values for the required cross-section of the
grounding conductor for the external grounding of the battery. The conductor dimensions depend
on the type and size of the battery connected, the external fuse (DC side) and the material used for
the grounding conductor.
The required cross-section of the grounding conductor can be calculated using the following
formula. Trigger times of about 25 ms are typical for short-circuit currents between 2,000 A and
10,000 A.
A grounding conductor with a 16 mm
2
cross-section is thus adequate for short-circuit currents up to
10,000 A.
DANGER!
Danger to life due to high voltages on the negative battery terminal flowing to
ground.
• Ground the battery.
A battery ground is not necessary only if the battery connections are safe to touch.
NOTICE!
Grounding the positive pole may irreparably damage the battery.
• Never ground the positive pole of the battery or the PV system.
Determining the cross-section
When determining the cross-section of the grounding conductor, all standards and
guidelines that apply at the installation location must be observed.
t = short-circuit duration in seconds
I
SC
= maximum battery current (short-circuit current) in ampere
S = conductor cross-section in mm²