72 Planning the electrical installation
Protection in short-circuit situations and against thermal
overload
Protecting the inverter and AC output cable in short-circuit
situations
The inverter has internal AC fuses, and optional AC breakers, which restrict inverter
damage, if there is a short circuit in the inverter. Install external protection (such as fuses)
according to local regulations to protect the AC output cables. Consider the AC line
voltage and the rated current of the inverter when you design the protection system. If no
low voltage AC protection device is installed, dimension the MV side protection of the
transformer so that it trips if there is a fault at the AC output of the inverter.
Protecting the photovoltaic generator and DC input cable in short-
circuit situations
The input DC fuses protect the inverter DC circuit and the DC input cables in a short-
circuit situation, when the cable is dimensioned according to inverter nominal DC current
and fuse ratings. Refer to Technical data on page 93.
If the inverter is delivered without input DC fuses (option +0F291), obey the instructions in
Inverters without input DC fuses (option +0F291) on page 76.
For the recommended DC input fuse options, refer to DC input fuse recommendations on
page 99.
Note: The inverter does not protect the photovoltaic generator. Install adequate
protection devices to, for example, each string.
Protecting the inverter and the AC output cable against thermal
overload
The inverter protects itself and the AC cables against thermal overload when the cables
are dimensioned according to the nominal current of the inverter. No additional thermal
protection devices are needed.
Protecting the DC input cable against thermal overload
The inverter protects the DC cables against thermal overload when the cables are
dimensioned according to the nominal current of the inverter. No additional thermal
protection devices are needed.
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