Probable causes:
1. Input Voltage or Frequency not in the range.
2. Waveform type is not a pure sine wave.
3. Capacity of the generator is less than UPS capacity.
Possible Solution:
1. Make sure Input Voltage is 230v and Frequency is 50hz.
2. Waveform type should be a pure sine wave.
3. Capacity of the generator should be 1.5 times more than the UPS capacity.
In case the issue persists even after trying the above troubleshooting, log the complaint.
Released for:APC India