Sunny Boy 2000
Technical Description
SB2000-11:EE
- 37 -
SMA Regelsysteme GmbH
Earth Fault Indicator
Isolation failure, defective varistor
Red LED on
The inverter indicates an earth failure with the red LED. This condition can occur to-
gether with other conditions indicated by the LEDs.
The ‘Earth Fault’ indication can be based on two different conditions: Either the PV-
panel connection has an isolation failure or at least one of the two thermally moni-
tored varistors on the DC side are defective and therefore do not let any current
pass.
The possible failures and methods to find out how to distinguish the reasons for the
failure are described in the following.
•
Isolation failure
An isolation failure has occurred at the PV-panel or its cabling. The plus or mi-
nus pole of the PV-panel or one of its modules has a connection (< 2 M
Ω
) to
the grounding earth (PE).
Any isolation failure must always be removed by qualified personnel
only.
A low resistance connection between the plus or minus pole and the grounding
can lead to highly dangerous electric shocks even if only one pole is touched.
Since the user himself normally is connected with the grounding he is highly in
danger when touching any pole.
