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000838BG
5 - Installation
String protection fuses
Sizing of fuses
The correct sizing of the
19
positive side and
20
negative side (-SX2, SY2
wiring box model) string fuses to be used to protect from “return currents” is
very important because it can considerably limit the risk of re and damage
to the PV generator.
A “return current” can be generated in the event of a fault and relevant
short-circuit at the ends of one or more PV modules of the system; this
condition can cause all the current supplied by the strings not involved in
the fault, but connected to the same input channel, to pass through the
faulty string.
For input connectors marked with “A” and “D” you must directly connect
the individual strings coming into the inverter (do not make eld
switchboards for parallel strings). This is because the positive side
19
and negative side
20
string fuses, situated on each input, are not rated to
take strings in parallel (array).
This operation could damage the fuses and consequently could cause
malfunctioning of the inverter.
The connection in parallel of the strings (array composition) could be
made upstream of the input connectors marked with “B” and/or “C” using
a proper Y quick t connector adapters: in this case the input fuses will
have to be replaced with a suitable size for the paralleled strings.
R S T N
19 20
CH1
1A 1B 1C 1D 2A 2B 2C 2D
3A 3B 3C 3D 4A 4B 4C 4D
5A 5B 5C 5D 6A 6B 6C 6D
CH2
CH3 CH4
CH5 CH6
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