System connected to UPS goes to sleep short time after power is lost

I was not able to solve the issue despite of my efforts. I was not even able to get any more information on the "Microsoft-Windows-Kernel-Power" so far.

The best I could do was a workaround: instead of using native Windows battery management I have installed APCUPSD software and I can no longer observer the issue. With this sotware Windows are not aware of the battery, the APCUPSD controls shutdown directly and I have verified it is not doing so prematurely.

I guess using APC provided PowerChute might work as well, but I did not like the sofware much when I installed it, sounds too much cluttered and obtrusive to me.