SMA WINDY BOY 3300 - Checking the Functioning of the Varistors

SMA Solar Technology AG Troubleshooting
Installation Guide WB33_38-IEN101830 59
9.3.2 Checking the Functioning of the Varistors
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.
You can check the functionality of the varistors in the following manner:
1. Open the inverter as described in section 7.2”Opening the Inverter” (page44).
2. Use a multimeter to check all the varistors in the
installed state to ascertain whether there is
aconducting connection between connectors
BandC.
Position of Varistors
The position of the varistors is 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)
Result Action
There is a conducting connection. There is probably a different fault in the inverter.
1. Close the inverter as described in section
7.3”Closing the Inverter” (page45).
2. Contact the SMA Serviceline.