Sunny Boy 700
Technical Description
SB700-11:EE
-
38
-
SMA Regelsysteme GmbH
Earth Fault Indicator
Insulation failure, defective varistor
Red LED on
The Sunny Boy indicates an earth failure with the red LED. This condition can occur
together with other indications.
The indication of “Earth Fault“ can result from two different reasons: Either the PV-
panels connection has an isolation failure or one of the two or both thermally moni-
tored varistors on the DC side have developed a high resistance and therefore do not
let any current pass.
The possible failures are described in the following together with the methods to find
out how to distinguish the reasons for the failure.
•
Insulation failure
Failure at the PV-panel or PV connection. The plus or minus pole from the PV-
panel or one of the PV-modules has a connection (< 1 M
Ω
) to the grounding
earth, PE.
The repair of an insulation failure must be conducted by quali-
fied personnel.
A low resistance connection between the plus or minus pole and the grounding,
displayed as an isolation failure, results in the possibility of highly dangerous
electric shocks while only touching one pole. That means that the user is in
danger when touching one pole since the user himself normally is connected
with the ground.