PROBLEM: Customer called that inverter was blinking red fast on the LED 1 indicator.
STEP 1 We visited the site to confirm the status of the system we log on into the inverter using the fusion solar app to check the alarm status, inverter was having alarm ID 2062(Low insulation resistance).
STEP 2: POSSIBLE CAUSE
We checked for poor wire connections between the pv panels probably caused by aging of cable junctions or poor cable quality(No fault detected)
We checked for pinched cable against pv aluminium structure(No fault)
Damaged pv panels was also checked(No fault)
STEP 3: FAULT DETECTION
1.AC connections was switched off
2.We measure the open circuit voltage and noted base on the expected voltage from the pv strings(Normal voltage)
3. We measure the dc cable insulation to ground using megger we observed poor insulation value
4.We disconnected all the DC wiring but keep DC+ and DC - from each other
5. We open the Man hole at the site we found that there was water ingress and damped condensation inside the man hole that result to excess moisture inside the DC cable conduit flex that was layed underground this cause the cable to suffer corrosion and some part of the cable became naked resulting to earth leakage.
SOLUTION:
We removed all the DC cable from the underground and replaced the faulty once with new cables and layed the cables above the ground using cement kerbs and cable tray. We decided to lay the cable above the ground this time because we observed that the area is always water logged during the raining season inverter was re-tested successfully the red blinking light indicator was no more and problem was successfully resolved.
