SMA WINDY BOY 3300 - Checking the Function of the Varistors

SMA Solar Technology AG Troubleshooting
Installation Manual WB33-38-IA-IEN120940 65
9.3.2 Checking the Function of the Varistors
Varistors are wear parts. Their functional efficiency diminishes with age or repeated strain 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 function of the varistors as follows:
1. Open the inverter as described in Section 7.2"Opening the Inverter" (page48).
2. Use a multimeter to check that in each of the
installed varistors there is a conductive connection
between terminals B and C.
Position of the varistors
The position of the varistors can be located with the help of the diagram below. Note the
following assignment of the terminals:
• Terminal A: outer terminal
(varistor connection with crimp)
• Terminal B: middle terminal
• Terminal C: outer terminal
(varistor connection without crimp)
Result What to do
There is a conductive connection. There is presumably a different error in the inverter.
1. Close the inverter as described in Section
7.3"Closing the Inverter" (page50).
2. Contact the SMA Service Line.