I am planning to use a common computer UPS with Desi UPS at back. The reason being Desi UPS produce Square waves which can damage computer parts. Since computer UPS are quite expensive for large backup, i think this setup should work. I expect this configuration should provide 1 to 1.5 hours backup.
I have short listed following models. I would request members who have any experiences with the following should suggest, or if you are using any thing else and like to recommend.
Galaxy Price: 5400 Rs.
CZone Price: 4900 Rs.