SMA AUTOMATIC SWITCH BOX M-20 - Manual (Page 35)

SMA Solar Technology AG 5 Electrical Connection
Installation Guide AS-BOX-M_L-IA-IEN110320 35
5.6 Connecting the PV Plant
Connecting other energy sources:
Instead of the PV plant, you can also connect other energy sources (e.g. small wind turbine systems)
to the Automatic Switch Box. In any case, make sure that an energy meter with the corresponding
tariff is connected to the Automatic Switch Box.
A mixing of energy sources (e.g. the connection of a PV plant and a small wind turbine system) is not
admissible on the part of the network operator since the supply rates of the energy sources differ.
TN systems: Overcurrent protective device
The Automatic Switch Box does not replace the distributor box or fuse box of the PV plant.
• Install a line circuit breaker between the Automatic Switch Box and the PV plant. Be sure to
observe all standards applicable to the installation site.
TT system: residual current device
The Automatic Switch Box does not replace the distributor box or fuse box of the PV plant.
• Install a residual current device and a line circuit breaker between the Automatic Switch Box
and the PV plant. Be sure to observe the requirements for residual current devices.
Requirements for the residual current device in the TT system:
☐ The residual current device is suitable for leakage currents of the PV inverter.
☐ The nominal tripping current is 100 mA maximum.
☐ Secure tripping with several residual current devices is provided if
g x ΣI
ΔN
≤ 100 mA.
g = coincidence factor of the residual current devices
ΣI
ΔN
= total of nominal tripping currents of the residual current devices
Coincidence factor
g = 1 corresponds to 1 residual current device in the system.
g = 0.5 corresponds to 2 ... 4 residual current devices in the system.
g = 0.35 corresponds to 5 ... 10 residual current devices in the system.
g = 0.25 corresponds to > 10 residual current devices in the system.
Cable Requirements:
☐ The cable is dimensioned according to the fuse between the feed-in meter and the
Automatic Switch Box and according to the cross-section of the connection terminals.
☐ In a Backup system with generator, the output fuse of the generator has been taken into account:
if the generator feed-in at the terminal strip "AS-X6/ Generator" has a higher fuse than the cable
of the feed-in meter, the cables of the PV plant are dimensioned for this increased fuse value.