6 Electrical Connection
SMA Solar Technology AG
Operating manual
SI44M-80H-13-BE-en-15
38
6.5.3.3
Connecting the Measuring Cables of the Automatic Transfer Switch
Relevant for systems connected to the utility grid
The Sunny Island measures the voltages of the respective line conductors via 1 measuring cable. In addition, the
master measures whether the tie switch has activated or deactivated (see circuitry overview in the quick reference
guide "SMA Energy System Home with Battery-Backup Function").
Cable route for control cables and measuring cables in the automatic transfer switch
An unfavorable cable route can lead to quality losses during the transmission of control signals and measured
values Observe the following rules for cable routes:
• Lay the control and measuring cables at the greatest possible distance from the power cables.
• Use shielded cables for the control and measuring cables.
• Always connect the digital input
DigIn
of the Sunny Island separately via a shielded cable.
Procedure:
1. On the Sunny Island, connect the measuring cable
X4 Ln
(Ln = L1 to L3) and
X4 N
for voltage monitoring to the
ExtVtg
terminal (see Section 6.6.7, page 62).
2. At the master, connect the tie switch monitoring. To do this, first connect
BatVtgOut-
with
DigIn-
within the
master(see Section 6.6.6, page 61).
3. Thread both insulated conductors through a ferrite included in the scope of delivery.
4. Connect the insulated conductor from
X5 3
to
DigIn+
.
5. Connect the insulated conductor from
X5 4
to
Ba
.
6.5.4
Connecting the Stand-Alone Grid or Multicluster-Box 6 / 36
Relevant for off-grid systems
In off-grid systems you connect AC loads and the grid-parallel AC sources (e.g. PV inverters) using an AC sub-
distribution board to the
AC1
terminal of the Sunny Island. In the case of a multicluster system, the Multicluster-Box 6
or Multicluster-Box 36 is the AC distribution board that is connected to connection
AC1
(for the connection of device
type MC-BOX-12.3-20 Multicluster-Box 12 (see Section 6.5.5, page 39).
Requirements for connecting Sunny Island inverters in single-phase parallel single-cluster systems:
AC
AC
AC
AC
AC
AC
AC
AC
☐ For a single-phase parallel single-cluster system, the cable length and conductor cross-section from each
Sunny Island to the AC distribution board must be identical. This will allow for stable and symmetric operation.
