SMA Solar Technology AG
Troubleshooting
Installation Guide
SB3300TLHC-IEN094121
33
3. Repeat step 2 for each string.
4. The table illustrated below shows the various results and corresponding measures.
9.1.2 Checking the Function of the Varistors
Varistors are wearing parts. Their functioning becomes restricted through aging or due to repeated
responses as a result of overvoltages. It is therefore possible that one of the thermallly monitored
varistors has lost its protective functioning, and thus the red LED is permanently lit.
You can check the functioning of the varistors in the following manner:
1. Open the Sunny Boy as described in section 7.1 ”Opening the Sunny Boy” (page 29).
Result
Measure
You have found a
ground fault
.
• The installer of the PV generator must remedy the
ground fault in the affected string before you may
reconnect the string to the Sunny Boy.
• Do not reconnect the faulty string.
• Close the Sunny Boy and operate as described in
section 7.2 ”Closing the Sunny Boy” (page 30).
You have found
no ground fault
.
It is likely that one of the thermally monitored varistors is
defective.
• Check the varistors as described in section
9.1.2 ”Checking the Function of the Varistors”
(page 33).
Position of varistors
The position of the varistors are to be determined with the help of the diagram below.
Observe the following allocation of the terminals:
• Terminal A: outer terminal
(varistor connection
with crimp
)
• Terminal B: middle terminal
• Terminal C: outer terminal
(varistor connection
without crimp
)
