Looking for advice on datacenter electrical/generator

Just to give a working example, we currently have 2 redundant UPS's that typically will have over an hour runtime each (at current load) and an estimated 10 minute runtime each under a full load. Our generator and genset have us up on alternate power in approximately 10 seconds barring any odd problems with the generator, but a weekly exercise would typically identify a problem like this which can hopefully be corrected prior to needing the generator. A manual override of the transfer switch is possible if a failure should ever occur in that as well. HVAC is powered by the generator when it's running but not by UPS because of the tremendous draw it would have on the UPS's shortening battery runtime. 4 HVAC units usually keep it pretty cool, around or 60 degrees Fahrenheit so 10 seconds of all of them being off is not a problem. Even 10 minutes wouldn't raise the temperature all that much where it couldn't be cooled down rapidly when power is back online. Our currently fuel capacity (at current load) will allow us to run off generator for a few weeks without refueling. I'm sure this is all pretty standard for most people with similar setups. Hope this helps!


My organization is in a growth phase right now and within the next year will find ourselves having outgrown our current 16KVa Symmetra. We have comissioned an electrical engineer to make a recommendation as to what is required to install a new 130Kva Liebert nPower UPS along with a generator.

Our current plan is to purchase the UPS with a minimal amount of battery, approximately 15min worth; just enough to get the generator running. Is this the better way to go? Or should we consider more battery? What is everyone's experience with the Liebert line of products? Any kudos or gripes? Our electrical engineer also recommended that we purchase a Generac generator and transfer switch. Any experiences with that company?

He also is strongly opposed to us purchasing a natural gas generator which seemed like a shoe-in for us. We have natual gas facilities and didn't want to hassel with the diesel maintenance problems. Is a natual gas generator something that we should consider?

Additionally he recommneded that we place the HVAC and lighting upstream from the UPS and use some sort of junction box to supply both the UPS load and the HVAC. How do you "big guys" do it? Here is a link to the diagram that he gave us today. Your thoughts are appreciated!


Dan Lockwood
Microsoft Certified Professional
CompTIA Network+ Certified
Cisco Certified Network Associate

Vinny Abello
Network Engineer
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