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Uninterrupted Power Supply Advise

Discussion in 'Power Supplies' started by locrieth, Apr 15, 2019 at 3:07 PM.

  1. locrieth


    Joined: Jan 22, 2005

    Posts: 344

    Location: Stoke-on-Trent

    Hi all,

    Just looking for a bit of advice regarding purchasing a UPS for my home server and network. At present I have a Dell R420 with dual 550 Watt PSUs which run a windows server 2016 VM and a Sophos UTM VM, a Cisco SG300 24 POE switch (which runs 3 POE APs and a CCTV IP camera), a Virgin Media SuperHub 3 and a media centre PC (i5 3330 with a bunch of drives).

    I've ran a power meter on the mains plug that they come from and it reads about 250 Watts while idling and when i ran prime 95 on both the windows server vm and the media centre they went up to about 325 Watts, so call it about 1.5 Amps.

    I've had a couple of trips on the power recently and I'm looking to try and mitigate short power drops, when all I need to do is flick the breakers back on. But if there is a longer power cut, gracefully shutting down the VMs, ESXi and the media centre PC in the battery time.

    Any advice on what i should be looking for? I've done a bit of research regarding standby, line interactive, etc and simulated sine wave vs. pure sine wave. What VA /wattage should i be looking at? And are there any brands to avoid or specifically go for, cyberpower seem to be coming across as a good reasonably priced brand?

    I don't really want to spend a fortune on one, but don't see the point in scrimping of one if its going to be rubbish.

    As always your advice is much appreciated, thanks for reading.


  2. EsaT


    Joined: Jun 6, 2008

    Posts: 5,182

    Location: Finland

    Just forget volt amperes, it's watts which are the important thing.
    And in this case it should be something like 400W to cover all situation.
    In time of power factor corrections it would have to be insanely reactive load for apparent output power to not be enough, if watt output is enough.

    Standby topology is the cheapest and least capable.
    Line interactive is better and those usually also have voltage regulation to correct some voltage fluctuations without switching to battery power.

    Simulated sinewave is what marketing uses for modified square wave.
    Would have to be awfully drunk for these to look even remotely sine wave shaped:

    Some old UPSes such high spikes that it would actually start rising near input tolerated by modern active-PFC PSUs.
    But in most properly made UPSes voltage is safe and waveform doesn't cause real problems for PCs.
    Sine wave output is lot more important for double conversion/online UPSes always powering load from inverter output.

    If you want normal UK power plugs to fit that's major factor.
    Most UPSes use IEC sockets.
    Cyberpower BRICs are one of the few UPSes with UK outlets.
    Out of flat box designs those appear to be also only ones with some ventilation.
    Cheap APCs are closed boxes designed to bake cheap capacitors dead.

    If you want like five minute operating time with some reserve left, smaller models lack in battery capacity.
    Also if battery capacity is tight then aging/wear of battery drops runtime to unusable level faster.
    BR1200 seems to have lot bigger battery capacity than smaller models.
    BR1000 has only 6 minute runtime for 300W load, while BR1200 has 9 minutes for 360W.