On 1/27/21 1:42 PM, Carlos E. R. wrote:
My experience with UPS may be limited, but back in the day I ran a
10-KVA UPS to power a group of Sun Microsystem servers. It was a
nice UPS with a ferroresonant transformer that conditioned power as
well as running the 10-KVA load for 30-minutes. In my experience,
we experienced more unplanned power outages caused by the UPS itself
than if we directly connected to the mains. After we retired the
Suns and switched to SuSE I once managed to keep the main server up
and running continuously for a bit more than 4-years, without the
UPS. Without a reboot! It was a busy server too, with a hardware
Do you remember how did the UPS fail? I'm curious.
The UPS never actually failed, except for a time or two when the
battery bank needed to be replaced. The unscheduled outages
were more due to me fiddling around with it and messing it up.
It was a Best Ferrups 10-kva model. Looks like they're still made:
The battery bank was in a separate container as big as the main
unit. They were free-standing, not rack mounted. It would power
the load through the saturated transformer and when power dropped
it would use the battery dc (switched I guess) to serve as the
AC input to the primary. The load would never see a glitch, until
the battery bank discharged. The saturated core of the transformer
served to regulate and smooth power to the load.