SMC Networks Sunny Mini Central SMC 5000A - Manual (Page 63)

SMA Technologie AG Troubleshooting / Problem Solving
Installation Guide SMC50A_60A-IEN073320 Page 63
11.2 The red LED is Continuously on
11.2.1 Ground Fault Testing
If the red LED on the Sunny Mini Central is continuously illuminated, it should be
checked whether there is a ground fault in the PV generator.
Follow the safety instructions in section 10.1 "Safety Instructions" (Page
58) and proceed as follows:
Step Instruction
1 Disconnect the Sunny Mini Central from both the DC and AC connections,
as described in section 10.2 "Opening of the Sunny Mini Central" (Page 59).
2 Taking one DC plug connector at a time,
measure the voltages between one DC plug
connector of a string and ground potential.
Pay attention to all safety instructions!
WARNING! Dangerously high voltages may be present.
Danger of death! Make sure that you only use measuring
devices with a DC input voltage range up to at least
600 V!
If the measured voltages are constant and their total is roughly the same as
the open circuit voltage of the string, then there is a ground fault in this string.
Its approximate location can be deduced from the relationships between the
voltages.