Rating For A Line Circuit Breaker - SMA Sunny Boy 1700 Installation Manual

SMA Technologie AG

9 Rating for a line circuit breaker

Example for the thermal rating for a line circuit breaker in a photovoltaic
electrical power unit operated in parallel with the low-voltage grid
We assume a PV system with 9 Sunny Boy 1700 inverters, with three inverters
per phase.
Betrie Betrie
Photo voltaik Opera b Photo voltaik Opera b
Photo voltaic -String wechs tion Photo voltaic -String wechs tion
string invert elrich Erdsch luss string invert elrich Erdsch luss
er ter Earth Fault er ter Earth Fault
Störun Störun
Failur g Failur g
e e
L1
L2
L3
N
Required technical information for the inverters used
• Maximum output current = 8.6 A
• Maximum permissible fuse protection for the inverter = 16 A
The choice of cable together with the way it is routed, ambient temperatures and
other underlying conditions limit the maximum fuse protection for the cable.
• In our example we assume that the chosen cable (2.5 mm²) is ideally routed and
can take a nominal current of 11.5 A.
Selecting a line circuit breaker:
• The maximum possible nominal current for the cable used and the maximum
possible fuse protection for the inverter now limit the maximum possible nominal
current for the line circuit breaker.
• In our example, 10 A is possible.
However, the thermal suitability of the line circuit breaker still needs to be checked.
Installation Guide
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Betrie
Photo voltaik Opera b
Photo voltaic -String wechs tion
string invert elrich Erdsch luss
er ter Earth Fault
Störun
Failur g
e
Rating for a line circuit breaker
Betrie Betrie
Photo voltaik Opera b Photo voltaik Opera b
Photo voltaic -String wechs tion Photo voltaic -String wechs tion
string invert elrich Erdsch luss string invert elrich Erdsch luss
er ter Earth Fault er ter Earth Fault
Störun Störun
Failur g Failur g
e e
SB1700-11:SE2006
Betrie
Photo voltaik Opera b
Photo voltaic -String wechs tion
string invert elrich Erdsch luss
er ter Earth Fault
Störun
Failur g
e
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