Question UPS recommendations ?

[martinlest]

Hi. I recently moved house here in the UK and find that my mains power supply is a bit erratic: in three months I have had at least four very short (microsecond) outages, enough to immediately shut down my PC of course (mostly used for X-Plane flight simulator). I used to have a Cyberpower CP1300EPFCLD, some years ago, which was fine for a while, but stopped working after a couple of years (not a battery issue), which left me somewhat unimpressed.

I have been looking at Riello UPS units, recommended by criticalpowersupplies.co.uk; seems they have a five-year warranty, as opposed to Cyberpower's one, which is a very big advantage of course.

But I have a problem with the terminology used on the site. All I knew is that I want a pure sinewave model. The two UPS units recommended are not cheap (especially now I am retired): 1. Riello Sentinel Pro 1kVA Online 230V 2. Riello Sentinel Pro 700VA Online 230V

I am told these are 'double conversion'. Googling a term I have never heard before, that seems to be a good thing! But are they pure sinewave? Or is that the same thing (??). Some other, somewhat cheaper Riello UPS units (e.g. the VST 1100) are described as being a ‘Line Interactive’ model. What does that imply?

I did buy a meter to see what my PC power usage is. It has a 650W PSU and according to the meter (sits between the mains socket and the PC lead) averages 250W usage, including any peripherals, peaking at 350w occasionally, with the flightsim programme in full swing..

Can anyone advise on all this please? Would folks recommend this brand (seems to get good comments online). It's quite a lot of money for me to part company with, so I want to ensure I get the best 'bang for my bucks', as well as being pretty sure I am not making an expensive purchase I am going to regret.. Thanks!

 

[BFG-9000]

Double-conversion means it is always running off the inverter and battery, while the battery is being charged from AC or not. There's no switchover time to running on battery because it is running from battery all of the time. Yes, this means it is less efficient, more expensive because the hardware has to be rated for continuous duty, and you may need to switch to a bypass mode in order to hot-swap batteries when the time comes to change them.

Line-interactive means it watches the sinewave of the incoming AC so when switchover occurs, the generated sinewave is more closely in phase with what the incoming power was. There's still a switchover time but it's less glitchy. You can hotswap batteries at any time but if the power goes out when they are out, it just shuts off.

Neither term has anything to do with sinewave, but generally the double-conversion units are so much more expensive that they usually are. Pure sinewave is important if you are running any AC electric motors or sensitive electronics, but the switchmode PSUs in computers don't care about that, and a stepped-approximation of sinewave is more efficient to generate than pure sinewave too.

Riello is an Italian company that generally makes good UPSes that cost less than comparable APC or Eaton

 

[martinlest]

Thank you very much for the useful answer - I will research/digest it further before I make any purchase!

In what way are double-conversion units 'less efficient' could you please say?

 

[BFG-9000]

Voltage converting isn't free, and double-conversion means it converts 230v AC to 36v DC and then back to 230v AC. If each conversion is 85% efficient then the overall efficiency is 72%, which with a little math means you'd use1/0.72 or 38% more electricity than if the load was plugged into the wall. This is not an issue if you are not paying for electricity, but be aware that your 350w load will thus require 483w and the extra 133w is being dumped into your room as heat too.

A standby system (such as the line-interactive type) may actually be rated less efficient because the inverters used can be cheaper since they only have to operate occasionally, however this lower efficiency only counts when running off battery and this type seldom do that. So no matter what load you put on these, so long as there is AC power available such units will consume less than 20w (which is mostly for the battery charger), making them on average use far less electricity.

Both of those Riello models are both sinewave and double-conversion. Note there is a third conversion as your SMPS converts that 230v AC to the 12v, 5v and 3.3v DC the computer runs on, and that conversion is generally more efficient from stepped AC power than sinewave too

 

[martinlest]

Yes, that's what I thought you must mean, in essence more expensive to buy and more expensive to run (yes, I do pay for my electricity use) . I am in a bit of a quandry now. My main 'worry' is buying a UPS which will turn out not to 'kick in' fast enough to catch these tiny (i.e. short) current outages: I worked in India and Sri Lanka for some years, and used a UPS there (very necessary). It often did not react fast enough to catch the frequent power cuts and so my PC would go off. But when I tested it, by switching off the power supply myself at the socket, it always worked as intended. I don't know why there would be that difference, I must admit. Made me a bit wary, in any event..

But maybe I do not need the rather 'wasteful' double-conversion technology to achieve 100% reliable intervention. Would a line-interactive UPS (Riello, most likely) be reliable enough in this regard, do you think?

None of these criteria were a factor when I bought my previous UPS - probably because I was just not aware of any of it! Until last week I knew of pure and simulated sine wave, and that was it. Now the world has become a bit more complicated!

Thank you again for your help

 

[martinlest]

Finally gone with the CyberPower CP1500EPFCLCD - I saw it went down in price by £50 yesterday, so.... Taken out 3-year extra warranty too. Hope I have made a good decision.