• Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
    Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.

UPS selection for computer, switch, modem APC

Y

Yowsers

n00b
Joined
Jun 7, 2004
Messages
60
http://www.newegg.com/app/ViewProductDesc.asp?description=42-101-128&depa=0

I am going to be supplying back up power for a Smoothwall Box (P3 733mhz 512ram, cdrw, 1hd, floppy, 250watt power supply), 24port Linksys switch, time warner cable modem (dont know model), and linksys accesspoint.

I am wanting to know if this particular product would be sufficient for this.

I am not wanting to supply backup for an extended period of time. I am just trying to prevent the reset of the smoothwall box after the occassional shortterm blackout. We've never had a blackout for more than 1 minute. I just don't want the computer, switch, access point, and modem to ever turn off. This is going to be for my home, which is why I do not need a very long backup time.

From what I've read on this forum, and the internet, this product will last (at full 300watt) approx 1.6minutes. Do all these products combine to be more than 300watts? I def do not want this to just backup for 1 second then shut off.

I used this (http://www.apcc.com/tools/ups_selector/index.cfm) and I typed in these things and that's how I came up with the item at newegg (see above).

Questions:

1) Is this UPS going to be sufficient?
2) If not, what do you recommend?

Any help would be greatly appreciated. Thanks!
 
I have the same battery backup, on the battery side are:
  • my main computer (400W)
  • a 486 ipcop computer (I think 100W)
  • an 8-port switch (4W)
  • a cordless phone (2.4W)
  • and an alarm clock (4W)
This model has two kinds of audible alerts, a slow occasional beep to let you know that it doesn't have power, and a fast "OH SHIT STOP DOING THIS TO ME" beeping. When my main computer is on, it does the second type :p and lasts maybe a minute.

One thing to note: I hooked up the alarm clock so that I if my power was out (I occasionally have extended outages at my apartment complex) I could turn off my computers and still have an alarm to wake me up in the morning. The one time this has happened so far, the clock somehow became about an hour and 15 minutes fast. I'm not sure what this means :confused:, but I figured you should probably know.

I doubt your setup will get up to 300W, so you should get around 2 minutes on that battery.
 
I think that model would be just fine for your power usage and needs. You may even be able to get away with the 350va model.
 
see I have no real idea of the average or worse case draw of the
24port Linksys switch, time warner cable modem, and linksys accesspoint

the definative answer would be to measure that with a watt meter
they are rather cheap and had at most hardware stores
a far fancier one is reviewed here
http://www.systemcooling.com/watts_up_pro-01.html

as far as what the PSU would actually pull thats dependent on both the load on it
(what its doing) and its efficiency at that load and temperature (Id guess it to be less that 100 watts on average and worsecase at 130W VDC
then factoring in AC Conversion and efficiency

well a supply @ 62% efficiency with a 65W VDC works out to about 105W VAC
a good guess for "typical"
a supply a 69% effeciency at 150W would draw 217W VAC not a bad worse case
(supplies have an effciency sweet spot I grabbed both of those from an FSP350 Mike Chin reviewed)

one of the other things to bear in mind is Power Factor Correction
Batteries dont like nonlinear loads


cut and paste
--------------------------------------------------------------------------------------------------------------



Power Supply System Integration Part 2: Battery Backup @ Power Electronics Technology

UPS Nonlinear Loads

Most end users are oblivious to the problems encountered when an online UPS interacts with nonlinear load, such as a switchmode power supply. Fig. 3, on page 42, illustrates the interface between an online UPS and a switchmode power supply. The switchmode supply within the host system consumes its current in high amplitude pulses, and as a result overloads the UPS, distorts its output and degrades in performance. This isn't the case if the SMPS has power factor correction (PFC); and in the United States most SMPS don't have PFC.

Repeated measurements under practical conditions show that in non-PFC SMPS, the current peak to rms ratio reaches a crest factor in the range of 2.5 to 3.5. This high crest factor imposes a difficult load for the UPS.

Manufacturers specify UPS capacity in volt-amperes, and set the UPS current limit with resistive loading. This affects the user in two ways: first, the actual power (in watts) that the online UPS can deliver is 75% to 80% of its VA rating. Second, the UPS cannot support a nonlinear load like a SMPS to full power capacity. In fact, it can support an SMPS only rated to 30% to 40% of its capacity. A 1kVA online UPS will only be suitable for backing up a system energized by a 300W to 400W (non-PFC) switchmode power supply. Attempts to draw higher power by the SMPS will severely distort the output of the UPS and may result in shutdown. Some UPSs support nonlinear loads to various degrees, but the above rule is safe to use as a guideline.

The whole idea of generating a high-purity sinewave within the UPS, and then rectifying it within the SMPS is wasteful. A UPS may be deployed to run non-electronic loads, such as lights or motors. However, this is a minor portion of the market for online UPS. Many applications back up computers and telecom devices, as well as instrumentation systems used for critical applications. In all of these applications, the immediate load for the UPS is the SMPS within the systems. Peak current and inrush current are associated with this load at startup. This current of 40A to 80A per SMPS will cause the UPS to shutdown due to overloading, or the UPS must transfer the load to utility to draw its inrush.
Click to expand...

Im "upgrading" the importance of active PFC in purchasing, as it does seem to have a great deal to do with not abusing and effectively employing the capacity of an online UPS (and by extention Id assume a line interactive UPS \ SPS when its on batteries, a far more common UPS scheme)


a bit more on PFC
PFC Decoded
and on UPSs
Power Conditioning 101
DIY UPS all @ dansdata ;)

--------------------------------------------------------------------------------------------------------------------------------

Id vote for research,
1 get a watt meter and measure the worse case for all the equipment involved
2. see if the supply is PFC or not
3. select a UPS based on that ;) (adding additional capacity for a nonlinar load)
 
You must log in or register to reply here.
Back
Top