Well around 4 AM when electricity came back on I noticed immediately that the bulbs in my room was fluctuating in response to low frequency AC. I immedietely unplugged every electronic in my room but wasn't fast enough to safe the routers in the house. The adapters to these routers are dead, I think. These routers were connected to a desi UPS.
My major concern was my telescope rig running on the rooftop. This system runs off a APC UPS and was afraid that something might end up being damaged but fortunately all is OK. Now here's my question:
Do APC UPS not supply power off the mains when they snse that the mains frequency is not around 50 Hz and instead keeps supplying power via the batteries? This is my guess since the routers which got damaged were on a desi UPS. The telescope rig also has a dedicated router (again powered via the APC UPS) so that I can monitor things from downstairs but this router seems A-OK and this is the same brand as the routers which were damaged (TP Link).
So what gives? Does the APC UPS provide adequate protection against such scenarios or do I need something more stronger?