Huawei SUN2000-8K-LC0 - Page 112

The possible causes are as follows:
● A short circuit has occurred between the PV array and the ground.
● The ambient air of the PV array is damp and the insulation between the PV
array and the ground is poor.
After the Low insulation resistance alarm is reported by the inverter, insulation
resistance fault location is automatically triggered. If the fault location is
successful, the location information is displayed on the Alarm details screen of
the Low insulation resistance alarm on the FusionSolar app.
Log in to the FusionSolar app, choose Alarm > Active alarm, select Low
insulation resistance to enter the Alarm details screen.
NO TE
● The positive and negative terminals of a PV string are connected to the PV+ and PV–
terminals of the SUN2000, respectively. The 0% position corresponds to the PV–
terminal, and the 100% position corresponds to the PV+ terminal. Other percentages
indicate that the fault occurs on a PV module or cable in the PV string.
● Possible fault position = Total number of PV modules in a PV string x Percentage of
possible short-circuit positions. For example, if a PV string consists of 14 PV modules
and the percentage of the possible short-circuit position is 34%, the possible fault
position is 4.76 (14 x 34%), indicating that the fault is located near PV module 4,
including the adjacent PV modules and their cables. The SUN2000 has a detection
precision of ±1 PV module.
● MPPT1 that may be faulty corresponds to PV1, MPPT2 that may be faulty corresponds
to PV2, and MPPT3 that may be faulty corresponds to PV3. Perform the following steps
to locate and rectify the fault.
● When a non-short-circuit fault occurs, the possible short-circuit percentage is not
displayed. If the insulation resistance is greater than 0.001 MΩ, the fault is not related
to short circuit. Check all PV modules in the faulty PV string one by one to locate and
rectify the fault.
Figure 8-2 Percentage of short-circuit positions
Procedure
NO TICE
If the irradiance or the PV string voltage is too high, the insulation resistance fault
location may fail. In this case, the fault location status on the Alarm details
screen is Conditions not met. Perform the following steps to connect PV strings to
the inverter one by one to locate the fault. If the system is not congured with
any optimizer, skip the corresponding optimizer operations.
SUN2000-(8K, 10K)-LC0 Series
User Manual 8 System Maintenance
Issue 01 (2023-09-15) Copyright © Huawei Digital Power Technologies Co., Ltd. 105