SMA SMC 9000TL Installation - Manual (Page 73)

Installation Manual SMC9-11TLRP-IA-en-51 73
SMA Solar Technology AG 10 Troubleshooting
Proceed as follows to check each string in the PV plant for earth faults.
1. Disconnect the inverter from all voltage sources (see section 9).
2. Measure the voltages:
• Measure the voltages between the positive pole and the earth potential (PE).
• Measure the voltages between the negative pole and the earth potential (protective
conductor).
• Measure the voltages between the positive and negative pole.
If the following results are present at the same time, there is an earth fault in the PV plant.
– All measured voltages are stable.
– The sum of the two voltages against the earth potential is approximately equal to the voltage
between the positive and negative poles.
• Determine the location of the earth fault via the ratio of the two measured voltages.
• Eliminate the earth fault.
If there is no earth fault and the message is still displayed, contact the SMA Service Line.
Example: Location of the earth fault
The example shows an earth fault between the second and third PV module.
3. Recommission the inverter (see section 8 "Commissioning", page 51).