UPS & Power Protection Facts

MartinD

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I used to work for a UPS company years back, and then I ran my own UPS sales company before I started trading, so I thought I'd share some of the useful stuff I learnt about the technicalities of UPS power supplies.

An interruption in the power supply to your trading workstation for less than a second will cause your system to crash, with additional consequences such as damaged hardware and corrupted software, EasyLanguage or data cache files. Brownouts, surges or other power fluctuations can have similar effects. Investing in a decent quality Uninterruptible Power Supply should be a "must have" peice of hardware for any serious day traders workstation. Most of us know this anyway, but while many of us know as much as we need to about specifying a decent computer, most everyone knows squat about the finer points of protecting that computer from the mains power supply.

"offline" UPS and basic surge protectors:
http://apcc.com/products/family/index.cfm?id=29
Belkin and most PC hardware stores sell surge supressors, some of which have rudimentary battery backup. APC's bottom of the range UPS is the "BackUPS" uninterruptible power supply. These low spec products are better than nothing, but in reality they give you very minimal protection from utility mains interference. During normal operation, they basically pass mains power directly onto your PC. While claiming to offer "filtered mains" this is misleading, because all they do is reduce the impact of spikes and RFI - MOV's clamp voltage spikes over a certain voltage down to the earth line - this means a 600V mains spike will have its peak lopped off, but a decent percentage of it will still give your computer PSU a nice shock. UPS of this type that offer basic battery backup work on the basis that when mains power fails, a relay closes and supplies battery power to an inverter to resume AC mains power. This invariably means a break in power of around 30ms or longer... dont beleive the 4-8ms transfer time claims on the brochure. 9 times out of 10 your computer PSU capacitors will have enough charge to bridge this gap, but is 90% reliability good enough when you have money on the line in the middle of a trade?

Line-Interactive UPS
http://apcc.com/products/family/index.cfm?id=165
"line-interactive" technology is a small improvement over offline UPS previously mentioned. It means that the device supplies more actively regulated and filtered mains power directly to your equipment. Usually a line-interactive UPS will have features to boost low voltage conditions and reduce high voltage conditions - both of which can put stress on your PC components, or in extremes cause damage to hardware and data. The way the UPS does this is via a multitap transformer - when it detects mains power dropping below a certain level, it will loop mains power through an extra coil on the transformer to boost the voltage up a stage. Spikes are still dealt with in the same manner as offline UPS by chopping the peaks off. An unfortunate side effect of using transformers to boost low voltages means that line-interactive UPS can actually boost spikes - so although a spike might have its peak chopped off, if you are experiencing a brownout at the same time your UPS will actually boost the reduced spike up again on its way out to your computer. They also have battery backup, but transfer to battery mode is still facilitated via a relay which means that there is still a small gap in the supply during switchover. This type of line-interactive UPS is the most basic standard of power protection that I would recommend. Online UPS technology is a far better, albeit more expensive solution - see next

Online / double conversion / redundant UPS
http://apcc.com/products/family/index.cfm?id=223
http://apcc.com/products/family/index.cfm?id=180
A true "online" type of UPS reconstructs the mains supply by artificially generating its own "pure" sinewave output powered continually by the UPS battery (which is constantly charged when the mains power is on) - so that your trading workstation is never directly connected to the raw mains supply. This means that your trading system is fully isolated from any kind of spike, noise or mains power disturbances, and because the UPS power output is driven by the battery there is no break in supply at all when the mains power should fail. You can also get this type of UPS in array's - the power equivalent of RAID hard drives, along with extended battery options for complete autonomy during blackouts.

So, without wishing to be completely anal (too late i suspect) about computer power, I hope the above info can be of use in helping anyone who is thinking about investing in backup power to spend their $$ effectively.
 
Interesting subject as I have installed UPS systems myself in the past for Banks and Call Centers but until recently I hadn't thought about installing one for myself until we had a power outage for 3hrs.

Thanks for jolting my memory and for the tech specs.
 
no problem - its easy to know all this stuff but fail to put it into practice.

one of the first companies I used to sell UPS for was so tight and stingy they never even had a UPS on their own server systems and PBX. Sods law and the first power outage knackers so much kit the final cost is way more than the best UPS money could have bought them would ever have cost.

For us as traders with real money on the line the consequential costs of being unable to execute a winning trade, or exit a losing trade make the small investment in the proper tools of our trade a factor worth getting right.
 
I agree, no full time trader should be without a UPS or alternative internet connection.

I'm lucky I can have ADSL, Cable and Wireless broadband available where I live.

JonnyT
 
Anyone know if I'm right in assuming that if I get an online UPS I can get one that doesn't last very long then power that by a portable petrol generator if the mains is off for a long time.
 
UPS and stanby power

Yes if you have intermediate power then you can use a backup generator we usualy use these in critical offices it is a good idea to run up the generator once in a while to ensure it will work.
 
Thanks for the answers. Think I'll go down that route. The mains went for 8.5hrs last week due to a fire at a scrap metal yard. Flames reached the overhead power lines which were the main source of energy into the area. Good way to find out how much redundancy the national grid has in it....my conclusion...not a lot (....bit like gas supplies then !!)
 
make sure the generator you get is sized roughly double the wattage rating of your UPS

The reason is that if your UPS is specced to deliver say 1kw output power, it will also have a battery charger that runs in parallel with the input to recharge the batteries whilst also supplying the load - so your input will be 1kw + charger load.

Additionally, there is a physics reason to do with the way that a PWM transistorized inverter places its current load on the sinewave that creates a side effect called harmonic distortion - not a problem on mains power but on a finite resource produced by a generator this can distort the AC voltage sinewave such that the UPS wont accept the input power from the generator and will keep flicking back onto battery mode - you get around this by over-rating the generator so that the distortion is minimezed.

Also worth making sure your UPS is actually proper double conversion online if your gonna use a generator, as small gensets dont have very precise 50hz frequency regulation - the frequency is a product of the rotation speed and clearly its very difficult to maintain a precise speed using a mechanical regulator on these little sets. if your UPS is online then the output frequency will be generated by the UPS not the generator so this isnt an issue
 
Arbitrageur, Thanks for that. I started looking last night at the specs. of UPS's & Generators and really didn't quite know where to start.
Cheers, Tuffty.
 
there have been a raft of exceptionally cheap brand new generators on ebay recently - definately worth looking into a generator as opposed to extended batteries - UPS battery packs tend to be pretty expensive, plus with a generator you can just keep topping it up with fuel and run indefinately.
 
Martin, (others) thanks for a very interesting article. I wonder if you could shed some light on a problem I have - Something that seemed to start with a whirring sound from my PC when I switched my UPS on in the morning and which led to a ballbearing clanking sound on occasions also seems to have ultimately resulted in problems with a Router (attached to UPS) which seems to have had its internals fried , my 4 port graphics card has lost a port (also attahec to PC attached to UPS), and my UPS failed to kick in on a recent power cut suggesting problems with switch as battery is new and OK. I mean jeez what the hell could have aused that - your reference to some kind of overcompensation with line interactive type might be the issue if that is what my [overly] cheap Leonics UPS type is. Don't understand how it could happen unless the spike is generated by the UPS at startup as it was switched off with a surge protector between mains and UPS.........The second or third time I switch on the UPS the "whirrr" (that length"whirr" sound) is absent and the PC starts without clanking noises( this suggests abnormally LOW not high voltage though?). It also starts with no "whirr" if I leave UPS switched on.

I am in Thailand and I NOW, through your input here, know that the online-double conversion-redundant type is the type to go for. Out of interest can an uneven power supply cause all kind of miscellanious sporadic type problems with PC's - I have hard this as an explanation in developing countries. PC's etc are really unbelievably problematic here and maybe this is why and the solution is a high spec UPS. The fact that they sell surge protectors in the supermarket probably tells me something about the power supply, but I have ben here 10 years and never heard an explanation.
 
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unstable power can knacker your PC through component stress - aside from any losses you incur through downtime when you should be trading - or closing a trade.

I'd seen some numbers from a telecoms & technology maintenance company around seven years ago that suggested that PC and telecom system technical and hardware problems could be halved through the installation of an online UPS. basically, for what their clients were paying for maintenance, it would be a cost saver for them to install a UPS as part of the maintenance contract, since it would mean they wouldnt have to send a technician out to site so often.

This was in the UK bear in mind, and I'd imagine our power here is waaay more stable than out in Thaland
 
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