SMA SB 3300TL Installation - Manual (Page 33)

SMA Technologie AG Exchanging Varistors
Installation Guide SB3300TL-11:SE2006 Page 33
8 Exchanging Varistors
The Sunny Boy 3300TL is a very complex technical device. Therefore there are only
a few possibilities to repair failures on site. Please do not try to make repairs other-
wise than described in this document. Make use of our exchange service and the re-
pair service of SMA Technologie AG.
If the red status LED is permanently on during operation please first make sure that
there is no ground fault in the PV generator. Only if the green LED is permanently on
at the same time, you can skip points 3 to 5 below.
4. If the voltages measured are constant and their total is approximately equal to
the open-circuit voltage of the string, there is a ground fault in this string. Its
approximate position can be deducted from the ratios of voltages.
1. Disconnect the grid (switch off the circuit brea-
ker), secure it against accidental reactivation
and ensure that it is disconnected.
Ensure that the AC voltage is off before
you open the Sunny Boy 3300TL!
2. Disconnect the DC plug connectors.
Disconnect the PV strings!
3. Measure voltages between one PV plug
connector and the ground potential. Follow all
applicable safety instructions!
Measure voltages between PV plug
connectors and the ground potential.
The voltage from the string is very dangerous! Be very careful and
pay attention to all applicable safety regulations!
1. 2. 3.
Off!
+ -
PE