WTS(UK) UPS - Page 1
Forum section: electronics / general

author: trevwhite
author_rank: Frequent Contributor
timestamp: October 26, 2015, 02:31:35 pm
content: The electricity has tripped 4 times today already and it is driving me crazy!UPS supplies? Do they output sine wave or square wave mains? Any recommendations new/second hand?ThanksTrev

author: helius
author_rank: Super Contributor
timestamp: October 26, 2015, 03:29:09 pm
content: UPS outputs a sine wave, but it may not be as clean as your power utility depending on its architecture. I'd recommend looking for a Liebert unit.

author: wblock
author_rank: Regular Contributor
timestamp: October 26, 2015, 07:36:31 pm
content: Output depends on the unit. Cheap UPSs have "simulated sine wave" or "stepped sine wave" output, which is more like a square wave:http://www.jkovach.net/projects/powerquality/. Even so, it works for most things. Better UPSs have true sine wave output. I've had good experiences with the APC Smart-UPS units, less so with the cheaper versions.One other difference: cheaper units tend to overcharge or overheat the batteries, leading to short life. I have a low-end APC that will reliably kill a battery in a year, and high-end ones with batteries that have been in use for at least five years and still have good life.

author: trevwhite
author_rank: Frequent Contributor
timestamp: October 30, 2015, 06:54:53 pm
content: Well I have foud one of these cheap, APC BR1500GI but it seems its a stepped sinewave which seems to mean square wave. Bit concerned it might damage my equipment. What do people reckon?

author: trevwhite
author_rank: Frequent Contributor
timestamp: October 30, 2015, 10:06:44 pm
content: Well to reply to my own post, I found a better output unit I thinkCyberPower CP900EPFCLCD Backup UPS PFC Pure Sinewave 900VA/540W 2 x UK Sockets 4 x IECThis seems to output a nice sine wave and there is a video on YouTube actually showing the its output in action. It looks much better!

author: trevwhite
author_rank: Frequent Contributor
timestamp: November 07, 2015, 11:21:20 am
content: An update on this. I have had the unit running for a week, tested it several times powering a PC, two screens and a bunch of test equipment all on and it works flawlessly. The display on the unit tells me exactly how much power I am using and the input and output voltages. I measured the output waveform and it is a lovely sine wave rather than the stepped sine waves. So far I am very happy with this unit.One thing I liked about the APC unit I was going to buy was that it had a connection on the back for external battery which is a very nice feature. In theory you could add an external battery to the CyberPower unit but I suppose when it tells you how long you have left the figures will be wrong as it expects only a 12V, 7Ah battery to be connected.

author: wblock
author_rank: Regular Contributor
timestamp: November 07, 2015, 02:56:31 pm
content: The APC units can run a calibration test to get accurate information about how long the batteries will run with the connected load. That is useful not just when other batteries have been added, but also as the stock batteries degrade with age.

author: trevwhite
author_rank: Frequent Contributor
timestamp: November 07, 2015, 03:34:51 pm
content: This CyberPower unit does indicate how long is left on battery but I did not really think about how it was doing it. If it is just down to the battery voltage under load then it may well give realistic indication of time left with any size battery attached. That's pretty good if so..

author: wraper
author_rank: Unknown
timestamp: November 08, 2015, 03:57:34 pm
content: APC is over-marketed junk and usually use some cheap chinese batteries which die very fast. They usually use some crap electolytic capacitors too. Look for Eaton, Riello if you can find some model which is affordable to you. Or maybe some other cheaper (decent) brand, but not APC.