Checking The Function Of The Varistors - SMA SUNNY BOY 1300TL Installation Manual

Failure Search
The approximate position of the ground fault can be determined from the ratio of the measured
voltages between the plus pole against ground potential (PE) and the minus pole against
ground potential (PE).
Example:
The ground fault is between the second and third module in this case.
☑ The ground fault check is finished.
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.
Position of varistors
You can determine the position of the varistors using the illustration below.
Observe the following allocation 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]).
Check the function of the varistors as described below:
1. Open the inverter as described in section 7.2 "Opening the Inverter" (page 39).
54 SB13_21TL-IA-IEN121060
SMA Solar Technology AG
Installation Guide