Checking The Function Of The Varistors - SMA SUNNY TRIPOWER 15000TL Economic Excellence Installation Manual

Troubleshooting
11.2 Checking the Function of the Varistors
If the inverter displays event number "7401", one of the varistors is probably defective.
Varistors are wear 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.
NOTICE!
Destruction of the inverter due to overvoltage
If varistors are missing or defective, the inverter is no longer protected against overvoltages.
• Replacement varistors should be obtained without delay.
• In PV plants with a high risk of overvoltages, never operate the inverter without
varistors.
Check the varistors as described below:
1. Disconnect the inverter (see Section 8 "Disconnecting the Inverter from Voltage Sources"
(page 55)).
DANGER!
Danger to life due to high voltages in the inverter
Death from electric shock
There is residual voltage in the inverter. The inverter takes 20 minutes to discharge.
• Wait 20 minutes before you open the upper enclosure lid or the DC lid.
CAUTION!
Risk of burns due to hot components inside the inverter
• Wait until the components inside the inverter have cooled down.
2. Release the screws of the upper enclosure lid. For
this purpose, use an Allen key (AF 4).
3. Pull the enclosure lid forwards to remove it.
74 STP15-20TLEE-IA-en-23
SMA Solar Technology AG
Installation Manual