SMA SB 3000TL-US Installation - Manual (Page 75)

SMA America, LLC 11 Troubleshooting
Installation Manual SB3-5TLUS22-IA-en-16 75
Proceed as follows to check each string in the PV system for ground faults.
1. Disconnect the inverter from any voltage sources (see Section 10).
2. Measure voltages:
• Measure the voltages between the positive terminal and the ground potential.
• Measure the voltages between the negative terminal and the ground potential.
• Measure the voltages between the positive terminals and negative terminals.
If the following results are returned simultaneously, there is a ground fault in the PV system.
☑ All measured voltages are stable.
☑ The sum of the two voltages against the ground potential is approximately equal to the
voltage between the positive and negative terminals.
3. Determine the location of the ground fault via the ratio of the two measured voltages.
4. Eliminate the ground fault.
5. Commission the inverter (see Section 7.2).
6. If there is no ground fault and the message continues to be displayed, contact the
SMA Service Line.
Danger to life due to electric shock
In the event of a ground fault, high voltages can be present in the PV module construction.
• Only touch the cables of the PV modules on their insulation.
• Do not connect DC cables with ground faults to the inverter.
Example: location of the ground fault
The example shows a ground fault between the second and third PV modules.