Power supply wattage and UPS question

Question

I'm trying to decide what rackable UPS to buy.   So I have a Poweredge 2850 with redundant power supplies. It says the power supply is rated at 700W.  Does this mean because I have redundant power my server is actually drawing 1400W while in use?    If so, what kind of UPS should I get?  Does this mean I need a 1430W / 2200VA UPS?  If I got a 480W UPS is that too small?  How do I know?  I'll have a small switch and a firewall on it too.   Thanks.

DELL-Charles R · Answer

Hello,

As you are aware this is a dated system.

I'm unable to find much information on it.

I have the hardware manual here but it does not list the PSU specs:

https://dl.dell.com/content/docu5165_CX700%20Storage%20Processor%20Enclosure%20Hardware%20Reference.pdf?language=en_us

I did find this posting with the PSU label

https://www.ebay.com/itm/404680464523?_skw=Original+Dell+EMC+Clarion+CX700+Power+Supply+118031924+XPE+9T607&itmmeta=01JQVR30839MY35H334PFJ4BHN&hash=item5e38d5d88b:g:bBYAAOSwMPxleh6k

Other than those I don't have any more information on the CX7200

Ferb · Answer

The system (according to the dell specs) will pull a maximum of 393 watts, when configured nominally.

http://www.dell.com/downloads/global/corporate/environ/PE_2850.pdf

The dual power supplies can each provide up to 700W, but this will never be met. And even though you have two power supplies, the 393W load is just going to be balanced between the two.

Following APC's little tool, it looks like a SmartUPS XL 1400VA would be great. They're pricier than the non-XL series, but allow you do daisy-chain battery packs for more runtime if you need it in the future. This is assuming you're using 120V mains. If you're using 208V, there are other 208V rackable power supplies too.

The 480W UPS would likely be right on the bleeding edge of power, thus minimizing the amount of backup power time available.

ferb!

speedstep · Answer

Going for cheap on an ups means it will die soon and or not work when you need it most.
Go with at least a 2500VA unit. REMEMBER THAT VA is not EQUAL TO WATTS.

What is the difference between a volt-amp (VA) and a Watt?
Equipment I have seen (such as computer backup power supplies)
have 2 different numbers for this rating. The watt rating is
typically 65% of the VA rating. So a 1000VA UPS is Actually 650 watts.
500VA UPS is 325 WATTS.

Ferb · Answer

A watt measures real power (so the real work that a machine does) whereas a VA measures TOTAL power (both real and reactive). So in a power supply, you need current to energize and magnetize transformers and induction coils, but a lot of this stuff is just reactive power and doesn't get transferred to the load.

The volt-amp rating on a back up supply shows how "bad" the load can get in terms of max current and max voltage. Power supplies with active power factor correction (PFC) are somewhere in the neighbourhood of 3% more VA than Watts. But an old style supply may be closer to 30-40%.

ferb!

jameskuder70 · Answer

How do I find the wattage for the following as I look for a UPS DELL_R660.2x16i_2.5GHz.64Gb_AC CX7200A Server

DELL-Charles R · Answer

Hello,   Here you can find PSU specifications for R660 Page 29 http://del.ly/61216FZqHw

jameskuder70 · Answer

@DELL-Charles R​ What about the CX7200 Server?

PowerEdge Hardware General

Power supply wattage and UPS question

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