SMA SB 4200TL Multi-String Installation - Manual (Page 33)

SMA Technologie AG Exchanging Varistors
Installation Guide SB4200TL-13:SE2006 Page 33
8 Exchanging Varistors
The Sunny Boy 4200TL Multi-String 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 otherwise than described in this document. Make use of our exchange service
and the repair 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 ap-
proximate position can be deducted from the ratios of voltages.
1. Disconnect the grid (switch off the circuit break-
er), secure it against accidental reactivation and
ensure that it is disconnected.
Ensure that the AC voltage is off before
you open the Sunny Boy 4200TL Multi-
String!
2. Disconnect the DC plug connectors of all strings.
Make sure that their allocation to the different
inverter input ports can still be recognized!
Disconnect the PV strings!
3. Measure voltages between one PV plug connec-
tor of each string and the ground potential. Fol-
low all applicable safety instructions!
Measure voltages between PV plug
connectors and the ground potential.
The voltage from the strings is very dangerous! Be very careful
and pay attention to all applicable safety regulations!
1. 2. 3.
Off!
+ - + -
String A String B
PE