LOW INSULATION FAILURE
PROBLEM: Customer called that inverter stop working. We visited the site to confirm the status of the system. We log on into the inverter with the help of the fusion solar app and check the alarm status through the alarm management we found that there was an alarm with ID2062 (low insulation Resistance)
POSSIBLE CAUSE:
1. We checked for poor connections between PV panels and ground
2. We check for damaged PV wire pinched against the mounting rail
3. We also check for damaged PV panel to confirm if it is broken
4. We also checked the grounding for the inverter.
FAULT DETECTION:
1. A/c,DC switch Connector was switched off
2. We measure the open circuit voltage from the pv strings and it was up to the expected value.
3. We measure the insulation polarity of one of the Dc cable to ground using megger we observe poor insulation
4. We disconnect all the DC cable from the inverter but keep the + and – from each other.
5. We check through the Cable trench to confirm if there is any earth leakage fault to ground from any of the PV strings cables we later discovered that there was water ingress and damped condensation inside the man hole this result to excess moisture which cause the cable to undergo degradation due to corrosion suffered which result to earth leakage
SOLUTION: We remove all the DC cable due to excess moisture that was discovered in the trench to confirm some of the cable that are still in good condition some of the cable where replaced and we decide to lay the cable above ground using kerbs and cable tray to avoid any form of future occurrence because the environment is always water logged during the raining season inverter was retested successfully.
