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.
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.
