Protection of people and equipment
Central grid and
system protec-
tion
The inverter offers the option to use the integrated AC relays as coupling
switches in conjunction with a central grid and system protection unit (in accord-
ance with VDE-AR-N 4105:2018:11 §6.4.1). For this purpose, the central trigger
device (switch) must be integrated into the WSD chain as described in the
chapter "WSD (Wired Shut Down)".
WSD (wired
shutdown)
The wired shutdown (WSD) interrupts the inverter feeding energy into the grid if
the trigger device (switch, e.g. emergency stop or fire alarm switch) has been ac-
tivated.
If an inverter (secondary device) fails, it is bypassed and the other inverters con-
tinue operating. If a second inverter (secondary device) or the inverter (primary
device) fails, the operation of the entire WSD chain is interrupted.
For installation, see Installing the WSD (wired shutdown) on page 98.
RCMU The inverter is equipped with a universal current-sensitive residual current monit-
oring unit (RCMU = Residual Current Monitoring Unit) in accordance with IEC
62109-2 and IEC63112.
This device monitors residual currents from the PV module to the AC output of
the inverter and disconnects the inverter from the grid in the event of unauthor-
ised residual current.
Insulation mon-
itoring
In the case of PV systems with ungrounded solar modules, the inverter checks
the resistance between the positive or negative pole of the PV system and the
ground potential before feeding energy into the grid. In the event of a short cir-
cuit between DC+ or DC- cable and ground (e.g. due to inadequately insulated
DC cables or damaged solar modules), an infeed into the grid is prevented.
AFCI - Arc Fault
Circuit Inter-
rupter (Arc
Guard)
AFCI (Arc Fault Circuit Interrupter) protects against arcing faults and in the nar-
rower sense is a protection device against contact faults. The AFCI evaluates any
DC-side faults that occur in the current and voltage curve with an electronic cir-
cuit and switches off the circuit when a contact fault is detected. This prevents
overheating on poor contacts and ideally possible fires.
CAUTION!
Danger due to incorrect or unprofessional DC installation.
The result is risk of damage and in turn, risk of fire to the PV system due to inad-
missible thermal loads that arise with an arc.
▶
Check plug connections are in good condition.
▶
Repair incorrect insulation as appropriate.
▶
Complete connections as per the specifications.
IMPORTANT!
Fronius will not accept any costs associated with production downtimes, installer
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