SMA 10000TL - The Red LED Is Flashing; Checking the Function of the Varistors (<Check Varistor>)

SMA Solar Technology AG Troubleshooting
Installation Guide SMC9-11TLRP-IEN100640 75
3. Repeat step 2 for each string.
4. The installer of the PV generator must remedy the ground fault in the affected string before you
may reconnect the string to the inverter.
5. Restart the inverter as described in section 7.3”Closing the Inverter” (page59), but without
reconnecting the faulty string.
9.4 The Red LED is Flashing
A flashing red LED can have different causes and depends on the corresponding fault indication on
the display:
• <Check Varistor> display message: At least one of the varistors is defective
(see section 9.4.1”Checking the Function of the Varistors (<Check Varistor>)” (page75)).
• <DC fuse> display message: At least one of the string fuses is defective
(see section 9.4.2”Replacing the String Fuses (<DC fuse>)” (page78)).
9.4.1 Checking the Function of the Varistors (<Check Varistor>)
Varistors are wearing parts. Their functional efficiency diminishes with age or following repeated
responses as a result of overvoltages. It is therefore possible that one of the thermally monitored
varistors has lost its protective function.
You can check the varistors as follows:
1. Open the inverter as described in section 7.2”Opening the Inverter” (page56).
Position of Varistors
You can determine the position of the varistors with the help of the illustration below.
Observe the following allocation of the
terminals:
• Terminal A: outer terminal (varistor
connection with loop [crimp])
• Terminal B: middle terminal
• Terminal C: outer terminal (varistor
connection without loop [crimp])