SMA SB 700 - Manual (Page 41)

SMA Technologie AG Replacing the varistors
Installation Guide SB700-11:SA2006 Page 41
8 Replacing the varistors
The Sunny Boy 700 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 earth fault in the PV generator.
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 earth fault in this string. Its
approximate location can be deduced from the relationships between the
voltages.
1. Disconnect the Sunny Boy 700 from the low
voltage grid (pull out the AC plug or switch the
line circuit breaker to its "off" position). Make
sure the grid cannot be inadvertently
reconnected.
You must make sure that no voltage is
present at the AC output before opening
the Sunny Boy.
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!
Disconnect the PV generators from the
Sunny Boy.
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!
Measure the voltage between DC plug
connectors and earth potential.
Caution! Dangerous high voltages may be present. Danger of
death!
1. 2. 3.
Off!
String 1
String 2
PE