SMA SB 2500TL-21 Installation - Manual (Page 77)

SMA Solar Technology AG Troubleshooting
Installation Manual SB25-30TLST-21-IA-en-13 77
☑ An earth fault is present if the measured voltages are stable and the sum of the voltages of
the positive pole against earth potential and the negative pole against earth potential of a
string is approximately equal to the voltage between the positive and negative poles.
Location of the earth fault
The approximate position of the earth fault can be determined from the ratio of the measured
voltages between the positive pole against earth potential (PE) and the negative pole against
earth potential (PE).
Example:
In this case, the earth fault is between the second and third PV module.
☑ The earth fault check is now complete.
Result Measure
☑ You have detected an earth fault. • The installer of the PV array must remedy the
earth fault in the affected string before you
reconnect the string to the inverter. You can
determine the location of the earth fault using
the illustration below.
• Do not reconnect the faulty string.
• Recommission the inverter (see Section 7.1
"Commissioning the Inverter" (page 52)).
☑ You have not detected an earth
fault.
One of the thermally monitored varistors is probably
defective.
• Check the function of the varistors (see Section
11.6 "Checking the Function of the Varistors"
(page 78)).