SMA
Technologie AG
Rating for a line circuit breaker
Installation Guide
SB2500-11:SE2006
Page 39
9 Rating for a line circuit breaker
Required technical information for the inverters used:
• Maximum output current = 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 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 are possible.
However, the thermal suitability of the line circuit breaker still needs to be checked.
When selecting line circuit breakers, a number of load factors need to be taken into
account. These can be found in the respective data sheets.
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 2500 inverters, with three inverters
per phase.
L1
L2
L3
N
...
Betrieb
Operation
Erdschluss
Earth Fa
ult
Störung
Failure
Photovo
ltaik-String
wechselr
ichter
Photovo
ltaic string
inver
ter
Betrieb
Operation
Erdschlu
ss
Earth Faul
t
Störung
Failure
Photovo
ltaik-Stringw
echselric
hter
Photovolt
aic string
inverter
Betrieb
Operation
Erdschlu
ss
Earth Faul
t
Störung
Failure
Photovoltaik-Stringwechse
lrichter
Photovo
ltaic strin
g inver
ter
Betrieb
Operation
Erdsc
hluss
Earth Fault
Störung
Failur
e
Photovo
ltaik-Stringw
echselr
ichter
Photovo
ltaic string
inverter
Betrieb
Operation
Erdsc
hluss
Earth Fault
Störung
Failur
e
Photo
voltaik-Stringw
echselr
ichter
Photovo
ltaic string
inverter
Betrieb
Operation
Erdschlu
ss
Earth Fau
lt
Störung
Failure
Photovoltaik-Stringwechs
elrichter
Photovolta
ic string
inver
ter
Summary of Contents for SUNNY BOY 2500
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Page 6: ...Table of Contents SMA Technologie AG Page 6 SB2500 11 SE2006 Installation Guide ...
Page 8: ...Foreword SMA Technologie AG Page 8 SB2500 11 SE2006 Installation Guide ...
Page 10: ...Safety information SMA Technologie AG Page 10 SB2500 11 SE2006 Installation Guide ...
Page 38: ...Replacing the varistors SMA Technologie AG Page 38 SB2500 11 SE2006 Installation Guide ...
Page 44: ...Contact SMA Technologie AG Page 44 SB2500 11 SE2006 Installation Guide ...
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