Replacing The Varistors - SMA Sunny Boy 2500 Installation Manual

SMA Technologie AG

8 Replacing the varistors

The Sunny Boy 2500 is a complex high-technology device. As a result, the
possibilities for fixing faults on site are limited to just a few items. Please don't try to
carry out repairs other than those described here. Use the SMA Technologie AG 24-
hour exchange service and repair service instead.
If the red LED on the status display glows continuously during operation, you should
first of all make sure that there is no ground contact in the PV generator. Only skip
points 3 to 5 if the green LED is permanently lit at the same time.
1. Disconnect the Sunny Boy 2500 from the low
voltage grid (switch the line circuit breaker to its
"off" position or pull out the AC plug). Make
sure the grid
reconnected.
2. Disconnect the DC plug connectors for all
strings. Make sure you note the order of the
individual inverter inputs so you can put them
back in the right place later!
3. Taking one DC plug connector at a time,
measure the voltages between one DC plug
connector of a string and earth potential. Pay
attention to the safety warnings!
Caution! Dangerous high voltages may be present. Danger of
death!
4. If the measured voltages are constant and if their total is roughly the same as
the open circuit voltage of the string then there is a ground contact in this string.
Its approximate location can be deduced from the relationships between the
voltages.
Installation Guide
cannot be inadvertently
Replacing the varistors
You must make sure that no voltage is
present at the AC output before opening
the Sunny Boy.
+ + + - - -
String 1
String 2
String 3
Disconnect the PV generators from the
Sunny Boy.
PE
Measure the voltage between DC plug
connectors and earth potential.
SB2500-11:SE2006 Page 35