Fronius Primo GEN24 3.0 Plus, Operating Instructions Manual, Page: 79 / 160

The following points regarding cabling must be considered:
- The main contacts of contactors K1 and K2 must be installed between the Fronius
Smart Meter and the residual current circuit breaker of the inverter and the residual
current circuit breaker of the backup power circuits.
- The supply voltage for contactors K1 and K2 is provided by the public grid and must
be connected to phase 1 (L1) after the Fronius Smart Meter and fused accordingly.
- Actuation of contactors K1 and K2 is carried out by the external grid and system pro-
tection unit.
- The external grid and system protection unit must be installed after the Fronius
Smart Meter. Precise installation and wiring instructions for the external grid and
system protection unit can be found in its separate Operating Instructions.
- The remote trip input of the external grid and system protection unit must be set to
NC according to the manufacturer's Operating Instructions.
- To ensure residual current circuit breakers function in backup power mode, the con-
nection between the neutral conductor and the ground conductor must be estab-
lished as close as possible to the inverter, but in any case before the first residual
current circuit breaker. An NC contact is used for this purpose for the main contacts
of contactors K4 and K5. This ensures that the ground connection is established as
soon as the public grid connection is no longer available.
- The supply voltage for contactors K1, K2, K4 and K5 is provided via phase 1 (L1) of
the public grid and is switched via the external grid and system protection unit.
- An NC contact for relay K3, which activates the remote input of the external grid and
system protection unit, interrupts the supply voltage to contactors K1, K2, K4 and
K5. This prevents the ground connection from being immediately disconnected
again when power returns to the public grid and the backup power network of the
inverter from being switched to the public grid.
- The NO contact of relay K3 gives additional feedback to the inverter on whether the
locking was successfully performed by relay K3.
- Additional inverters or other AC sources can be installed in the backup power circuit
after the main contacts of K1 and K2. The sources are not synchronised to the net-
work of the inverter because this backup power network has a frequency of 53 Hz.
Testing backup
power mode Backup power mode should be tested once it has been installed and set up for the first
time. A battery state of charge of over 30% is recommended when in test mode.
A description on how to run test mode can be found in the backup power checklist
(https://www.fronius.com/en/search-page, item number: 42,0426,0365).
79
EN