SMA SUNNY BOY 3.8-US User Manual page 54

8 Troubleshooting
• 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.
• 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.
Example: Location of the ground fault
The example shows a ground fault between the second and third PV module.
3. If a definite ground fault cannot be measured and the message is still displayed, measure the
insulation resistance.
4. Reconnect the strings without ground faults to the inverter and recommission the inverter (see
inverter installation inverter).
Test by Measuring the Insulation Resistance
If the voltage measurement does not provide sufficient evidence of a ground fault, the insulation
resistance measurement can provide more exact results.
Figure 4: Schematic diagram of the measurement
60 SB30-77-1SP-US-40-BA-en-11
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User Manual