SMA SI 3.0-11 Installation - Manual (Page 26)

7 Electrical Connection SMA Solar Technology AG
26 SI30M-44M-60H-80H-IA-en-30 Installation Manual
Conductor cross-section:
You must determine the required conductor cross-section of the grounding conductor, taking into account the applicable
local standards and directives. The calculation of the grounding conductor cross-section depends on the type and size of
the connected battery, the external fuse in the BatFuse, and the material of the grounding conductor.
Cable requirement:
☐ Copper wire
☐ Maximum conductor cross-section: 16 mm²
☐ The cross-sections of the battery grounding conductor and Sunny Island inverter grounding conductor must be the
same.
Procedure:
1. Calculate the cross-section of the grounding conductor.
2. Ground the battery at the positive terminal or negative terminal using a conductor with the calculated cross-section.
3. Also ground the Sunny Island enclosure using a conductor with the calculated cross-section, as follows:
• Strip the grounding conductor.
• Place the clamping bracket over the conductor. Position the
conductor on the left.
• Fasten the clamping bracket with the hexagon socket screw
M6x16 and a conical spring washer (AF 5, torque: 4 Nm to
5.7 Nm). The teeth of the conical spring washer must face the
clamping bracket.
Example: Calculation of the grounding conductor cross-section
Grounding conductor made of copper. The required cross-section of the grounding conductor can be calculated using
the following formula:
SC
u
I
SC
t
= conductor cross-section in mm²
= short-circuit current in A
= interruption time in s
Typical tripping times for an LV/HRC fuse are around 25 ms for short-circuit currents between 2,000 A and 10,000 A.
Grounding with a cross-section of 16 mm² is sufficient for short-circuit currents up to 10,000 A.