SMA SB 2500 Installation - Manual (Page 58)

Troubleshooting SMA Solar Technology AG
58 SB25-30-IA-en-51 Installation Manual
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 overvoltage. It is therefore possible that one of the thermally monitored varistors has lost its
protective function, and thus the red LED is lit.
Check the function of the varistors as described below:
1. Open the inverter as described in Section 7.2 "Opening the Inverter" (page 44).
2. Using a multimeter and with both varistors installed,
determine whether there is a conductive connection
between terminals B and C.
Position of varistors
You can determine the position of the varistors using the illustration below.
Observe the following assignment of the
terminals:
• Terminal A: outer terminal (varistor
connection with loop [crimp])
• Terminal B: middle terminal
• Terminal C: outer terminal (varistor
connection without loop [crimp])
Result Measure
☑ There is a conducting connection. There is probably a different error in the inverter.
• Contact the SMA Service Line
(see Section 13 "Contact" (page 71)).