UPS Load based on average or full load

[aac]

Hi all

 

A bit of advice as I am currently in the market for replacing x2 10 year old APC 2200VA UPS's. The current setup is that we have 2 PDU's one going to each UPS and one of 2 power supplies from each server, switch etc goes into each PDU. If I calculate the load in watts going in to each PDU it would be about 6700 each if based on the full capacity of each power supply ie 800w per PSU for server etc... which is what dosen't make sense to me as it is clearly miles above the capacity of the UPS. I have had conversations with Eaton and APC who will only calculate it based on full capacity but someone else is telling me the reason all is fine and I should calculate it based on average consumption per device is that each device is using such a minute amount of power in reality. Having looked at this I can see where he is coming from as a server with dual 800w PSU's each PSU is drawing around 60w each with average combined of just under 120w. Having drawn up a spreadsheet calculating the value of each device it is consuming considerably under the capacity of the current UPS however Eaton and APC do not want to sell me anything less than x2 8000va. My question is what is everyone else doing?

 

Thanks in advance

[TheRobins]

Morning,

 

Those figures are obviously for the server being at full load which we know is very unlikely 24/7. If you know how long your current solution runs your systems for and its suitable why change it. I recently changed my timings on our ups to just give us around 15 minutes before shutdowns are started, during testing battery only went down to around 65%. I use the most recent APC2200, it runs 2 hyper-v hosts, core switch, 2 x 24 port POE plus switches for phones and wifi, 2 x 48 port switches, firewall and BT fibre kit and 2 desktop PC's. Unless you need longer it would just go for 2 new APC2200's. Sure if I added 2 we could probably run for a couple of hours if needed.

Edited February 6, 2024 by TheRobins

[dmj]

Can't you just replace the batteries with APC compatible? or is there a feature that you are missing?

[PotNoodleTech]

If you are taking the rating of the power supply e.g. 2 x 1000w power supplies that doesnt mean the server can or will use 2000 watts it just means that is what the maximum of the power supplies are rated to. Generally a normal server will use 200watts ish and maybe a big dual cpu with 30 hard drives will use 500-700 watts max.

 

If you use the max power supply rating you will be buying a UPS about 10x the size you need and wasting loads of money.

 

Best way is to actually measure each server one at a time - run something like cinebench on them to use 100% cpu and measure the watts - then tot all that up for all servers and that should give you a good idea of the max power you'll use.

[aac]

Thankyou for all your replies. I have gone for a slight upgrade from the 2200 buying x2 Eaton 3000va models

[TheRobins]

Plenty of capacity in those, interesting to see how the network controls are on the Eaton as I am so used to APC.

[PotNoodleTech]

Thankyou for all your replies. I have gone for a slight upgrade from the 2200 buying x2 Eaton 3000va models

 

Nice you won't regret it Eaton are superior to APC especially when it comes to battery management and replacement - they seem to last forever. My pair of Eaton 5000 are over 5 years old on original batteries and still getting 1 hour 10 mins runtime.