9 Troubleshooting
SMA America, LLC
78
SB3-5TLUS22-IA-en-10
Installation Manual
9.6 Replacing DC Varistors
In regions where storms or other DC overvoltages frequently occur, the DC varistors lose their
functionality if the PV plant is not equipped with additional overvoltage protection. In such cases, SMA
recommends replacing DC varistors with new ones after an operating period of 10 years in order to
ensure that the functionality of the DC varistors remains at a constant level.
Order new varistors direct from SMA (order numbers (see Section 12 "Accessories", page 89)).
1. Disconnect the inverter and the DC Disconnect from voltage sources (see Section 8).
2. Insert the insertion tool into the clamp contacts of
the terminal block.
3. Pull the varistor out of the connecting terminal plate.
4. Insert the new varistor into the terminal. The labels
of the varistor must face to the right to the inside of
the inverter.
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.
• Only re-commission the inverter after you have replaced the defective varistors.
