SMA SB 3300 Installation - Manual (Page 58)

Troubleshooting SMA Solar Technology AG
58 SB33_38-IEN111851 Installation Guide
9.3 Red LED is Glowing Continuously
If the red status display LED lights up continuously during operation, there is a ground fault in the
PV generator or at minimum one varistor for overvoltage protection is faulty.
Procedure
1. Check for ground faults in the PV generator as described in section 9.3.1 ”Checking the PV
Generator for a Ground Fault” (page 58).
2. If the red LED continues to glow, check the varistors as described in section 9.3.2 ”Checking the
Function of the Varistors” (page 60).
9.3.1 Checking the PV Generator for a Ground Fault
1. Disconnect the inverter from both the DC and AC connections as described in section
7.2 ”Opening the Inverter” (page 43).
2. Measure the voltages between the plus pole of the
strings and the ground potential (PE).
3. Measure the voltages between the minus pole of
the strings and the ground potential (PE).
DANGER!
Risk of lethal electric shock!
• Only touch the cables of the PV generator on their insulation.
• Do not connect strings with ground faults to the inverter.
NOTICE!
Excessive voltages can destroy the measuring device!
• Use only measuring devices with a DC input range of 1 000 V at minimum.