SMA SSM16-11 - Manual (Page 40)

6 Electrical Connection SMA Solar Technology AG
40 SSM16-24-IA-IEN105120 Installation Guide
6.6 Connecting the Remote Tripping for the DC Circuit Breaker
6.6.1 Dimensioning the Connection Cable for the Shunt Trip
The Sunny String-Monitor optionally includes a DC circuit breaker with a remote trigger. The remote
trigger consists of a shunt release and a feedback contact. The shunt release can be implemented as
a shunt trip or undervoltage release.
In order to achieve reliable tripping, the minimum cross section of the connection cable on the shunt
trip must be determined. The choice of connection cable cross section depends on the following
factors:
• The number of Sunny String-Monitors connected
• The length of the cable supplying the voltage
• The cable lengths between the Sunny String-Monitors connected
Figure 16: Relationship between cable length, number of Sunny String-Monitors connected and cable cross-
section.
1. Determine the number of DC circuit breakers.
2. Determine the greatest distance between the Sunny String-Monitors or the voltage supply and
the first Sunny String-Monitor.
3. Read off the minimum cable cross section from figure 16.
Example: Dimensioning a Connection Cable
In a PV plant there are 20 DC circuit breakers. The greatest distance between the
Sunny String‑Monitors is 150 m.
The cable cross section must be at least 4 mm
2
.