12 Troubleshooting
SMA Solar Technology AG
Operating manual
SB55-LV-JP-41-BE-en-13
83
• If the voltage measurement was not successful, check the PV system via insulation resistance
measurement for ground faults.
Test by Measuring the Voltage
Proceed as follows to check each string in the PV system for ground faults.
Procedure:
1.
DANGER
Danger to life due to high voltages
• Disconnect the inverter from all voltage sources (see Section 10, page 59).
2. Measure the voltages:
• Measure the voltage between the positive terminal and the ground potential (PE).
• Measure the voltage between the negative terminal and the ground potential (PE).
• Measure the voltage between the positive and negative terminals.
If the following results are present at the same time, there is a ground fault in the PV
system:
☑ All measured voltages are stable.
☑ The sum of the two voltages to ground potential is approximately equal to the
voltage between the positive and negative terminals.
3. If a ground fault is present, determine the location of the ground fault via the ratio of the two
measured voltages and eliminate the ground fault.
4. If a definite ground fault cannot be measured and the message is still displayed, measure the
insulation resistance.
5. Reconnect the strings without ground faults to the inverter and recommission the inverter (see
inverter installation inverter).
Location of the ground fault
The example shows a ground fault between the second and third PV module.
