SMA SSM16-11 - Manual (Page 16)

3 Product Description SMA Solar Technology AG
16 SSM16-24-IA-IEN105120 Installation Guide
Polling Interval
The Sunny String-Monitor continually measures the string currents and saves them in cycles. The data
logger reads these values every 5 minutes.
Tripping Time
The tripping time is the time span between the occurrence of a fault and the error message. The
tripping time is set to 180 minutes as default. You can set the parameters for the tripping time between
2 … 1440 minutes.
Tolerance
The tolerance indicates how much the string current may deviate from the mean value. When the string
current is outside of the tolerance limits, the data logger detects the deviation and stores it. The
tolerance can be set between 10% … 100%.
Grouping Strings
You can assign the strings to the 8 measuring channels in order to simplify monitoring. Should
individual PV strings be overshadowed, aligned differently or fitted with different modules, it is also
possible to group the individual measuring channels. This makes it possible to compare measuring
channels with the same properties.
Comparison
Every 5 minutes, the data logger compares the string-current with the mean value for the group. If the
string-current exceeds the tolerance limit, the data logger stores the deviation. If at the next poll, there
is still a deviation between the string-current and the mean value, the deviations are added together.
If the sum of deviations exceeds the error sum, the data logger sends the 380 "SMU" warning. When
the error is acknowledged, the error sum is reset, and the warning disappears from the display.
It is possible to see from the Sunny Central Control or via the Sunny WebBox which Sunny String-
Monitor and which measuring channels are deviating from the mean value for the group.
Example:
It is assumed that at time t
0
the mean value of a group is 5 A. The set tolerance is 10%. This means
that the tolerance range is from 4.5 A … 5.5 A. The tripping time is set to 10 minutes. The polling
interval is 5 minutes. The error sum can therefore be calculated as follows: