11 Troubleshooting
SMA Solar Technology AG
80
STP5-9TL-IA-en-10
Installation Manual
3. Recommission the inverter (see Section 8).
11.6 Checking the Function of the Varistors
If the inverter displays event number
7401
, one of the varistors is probably defective. Check the
function of each varistor as described below.
Example: Location of the earth fault
The example shows an earth fault between the second and third PV module.
Destruction of the inverter due to overvoltage
If varistors are missing, the inverter is no longer protected against overvoltage.
• Do not operate the inverter without varistors in plants with a high risk of overvoltages.
• Do not recommission the inverter until the defective varistors have been replaced.
Destruction of the measuring device due to overvoltage
• Only use measuring devices with a DC input voltage range up to 1,000 V.