SMA Solar Technology AG
11 Troubleshooting
Installation Manual
STP5-9TL-IA-en-10
79
11.5 Checking the PV Plant for Earth Faults
If the inverter displays the event numbers
3501
,
3601
or
3701
, there could be an earth fault.
The electrical insulation of the PV plant to earth is defective or insufficient.
Proceed as follows to check each string in the PV plant for earth faults.
1. Disconnect the inverter from voltage sources (see Section 10).
2. Measure voltages:
• Measure the voltages between the positive pole and the earth potential (PE).
• Measure the voltages between the negative pole and the earth potential (PE).
• Measure the voltages between the positive and negative poles.
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 (PE) is approximately the same
as 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.
Danger to life due to electric shock
In the event of an earth fault, high voltages can be present at the PV array.
• Only touch the insulation of the PV array cables.
• Do not touch parts of the sub-structure and frame of the PV array.
• Do not connect strings with earth faults to the inverter.
Destruction of the measuring device due to overvoltage
• Only use measuring devices with a DC input voltage range up to at least 1,000 V.