PC Peripherals Of PSU, UPS, PFC and Sine wave

Discussion in 'Computer Hardware' started by tangentray, Jul 10, 2008.

  1. tangentray

    tangentray Well-Known Member

    Ok, a lot of talk is now going on about PSU and UPS compatibility. That is mostly because, many of us who prefer buying better to best components for our beloved rigs find that arguably most of the best PSU-s (Corsair, Tagan etc.) are not compatible with the undoubtedly best UPS-s i.e the house of APC.

    The Problem:
    Most new and sophesticated PSU-s have active PFC-s. Active PFC is incompatible with simulated sine wave output, it would only work with pure sine wave. The problem is more financial in nature. It is not that APC does not produce UPS wich output pure sine wave but they are the best server class pieces which come at a premium ~>10k. Now many of us have never thought about that while buying, once bought then only we find this out. So we are left with either changing our UPS or PSU!!!

    What will happen if I run my active PFC PSU along with simulated Sine wave UPS?
    In an ideal case, with power cut in this scenario the UPS starts providing simulated sine wave, the PSU expecting a pure sine wave would power down killing your system, the UPS sensing no load will shutdown as well. In short your system will behave like it has no UPS backup at all. A lot of deviations have been seen though. For example the Corsair VX450 is reported to have run without any hitch, other good psu-s would run with a heavy humming noise due to overload. We would all agree it would be a bad idea to take a chance with our precious monnies err.. hardware. :p

    A little about PFC:
    A lot of articles already here on this very forum about this. So will keep it short. A complex electrical system has mainly two kinds of loads resistive(simple resistance) and reactive(capacitance and inductance). In an AC circuit the lag or angle between the voltage and current depends on the reactive part of the circuit. The actual power consumed by the circuit is proportional to the product of voltage, current and cosine of the angle between voltage and current. So the more reactive circuit means more lag means lesser value of the cosine factor means the ciruit will be able to
    draw much less power even when it feeds on a main line which is actually able to give a maximum power equal to voltage multiplied by current that is when cosine of lag is 1 that is when lag is zero => only resistive load.
    The power factor of a circuit = true power / apparent power in this case it is (voltage X current X cos [lag]) / (voltage X current). So obviously to increase the power factor would mean to make the circuit more efficient. That is where PFC (Power Factor Correction) comes in. Not delving into complex descriptions let us just say that with PFC we add something to the actual circuit so that from outside the circuit behaves more like a pure resistive circuit thus increasing it's efficiency.
    PFC can active where a circuit sucks power from the mains in a resistive way, and feeds it to the low power factor circuit on the other side, isolating the mains from whatever the circuit is doing.
    Passive PFC uses a capcitive or inductive filter to enhance power factor. Active PFC is more efficient than the passive method.

    So what to buy?
    All APC Smart UPS and high end models have pure sine wave, but the cost a lot. So you can opt for that if you want to( and are rich :hap2: ). For people who are already stuck with lower models of APC UPS(which also do not come cheap :no: ) there is the option of none PFC and passive PFC models. All el cheapo unreliable PSU-s are none PFC. Passive PFC is becoming rarer by the day but still avaiable the Cooler master Extreme Power series and the Gigabyte Superb power series fall into this category. Please add more if you know of.

    Anyways that is all I wanted to tell. It might be something that you already know, but for noobs like me I thought it might be helpful. Post your suggestions.
  2. VanishingNerd

    VanishingNerd New Member

    Very well done!! All the relevant information in avery concise fashion.

    I would like to add my personal case regarding this section. In my case the Corsair TX750W caused the APC 800VA Back UPS's max load to come down from 540W to ~250W. The APC guy was flummoxed by what was going on. The same UPS had been performing perfectly with the Cooler Master Extreme Power 600W I had prior to my getting the TX750W. In the end I sold it off to a guy who had the Cooler Master Extreme Power 600W.
  3. amigoatul

    amigoatul Well-Known Member

    Hey helpful post dude so thanks for the info coz i had no idea abt this. BTW I have a basic APC UPS with a Corsair VX 450 psu and during a power cut,my rig luckily doesnt turn off but ive got to observe if it runs any louder or not.But i dont think it does.
  4. HailStonE

    HailStonE Well-Known Member

    Good information..... repped..

    APC spec. says "Stepped Sinewave" for Battery current.... Is this the stimulated Sinewave
  5. OP

    tangentray Well-Known Member

    Yes stepped sinewave is simulated sine wave. The other would be 'pure' sine wave.
  6. fangface

    fangface Active Member

    nice article man!

    Other than the APC Smart UPS series and the other higher end models, are there any alternative choices which can be considered?
  7. VanishingNerd

    VanishingNerd New Member

    From APC itself no.

    From other manufacturers there are a lot of choices, all much cheaper than the ~9k for 750VA Smart UPS which is the least you will pay for a pure sine wave UPS from APC. Only thing is the reliability of such equipment.:no:
  8. HailStonE

    HailStonE Well-Known Member

    ^^ How is Liebert from Emmerson ???
  9. kgthelazy

    kgthelazy New Member

    hmmm BTech EE seepage from that post.

    nice article btw
    mayanks_098 likes this.
  10. OP

    tangentray Well-Known Member

    lol ... :p
  11. Tron05

    Tron05 Active Member

    Will the Microtek 800VA double battery UPS work fine with a corsair vx450??
  12. Eazy

    Eazy New Member

    FYI - APC have one newer SmartUPS model SC 620VA 230V which they mention the waveform being of type "Stepped approximation to a sinewave"

    APC Smart-UPS SC 620VA 230V
  13. Infected

    Infected Well-Known Member

    The issue we are talking bout here will only occur if we load the UPS to nearly its max capacity, and not when it is not close to its max capacity load wise.


    If your APC UPS BackUPS 800(a simulated sine wave one) with and its max load capicity 540 Watts / 800 VA.

    Lets say you are using Corsair 620HX(ActivePFC)

    Case 1: Your computer is only drawing say less than approx 439Watts (80% of max of load for the UPS), you will not hear the whining sound and will have no issue.

    Case 2: Your computer is drawing say more than approx 439Watts (80% of max of load for the UPS), lets say like 550 watts or so, you WILL hear the whining sound and can have an issue with either of the compnents if used for an extended period.

    "Yes stepped sinewave is simulated sine wave. The other would be 'pure' sine wave."

    ""Stepped Sinewave" for Battery current.... Is this the stimulated Sinewave"

    No there is a difference between all 3.

    Pure sine wave: This is a pure sine way as it says, it is a constant slope on a graph, if you know what I mean, it is a constant change, there are no edges/steps in the wave.

    Stepped sine wave: A stepped sine way is not a pure sine wave but it is incremented in smaller steps, instant of a constant slope it has edges in the graph.

    Simulated Sine Wave: Here we use Squares or Trapeziums to Simulate a sine wave.

    The following are from Google hope they help you all understand.


    Hope this helps.

    Have a nice night,


    NOTE: I would like to know how many people use a Back-UPS 1000 ie a Sine wave 1000va model with a 450VX and are having problem? I dont think anyone should, if so please add to this thread, as I would like to further investigate the issue then.
    1 person likes this.
  14. ..:: Free Radical ::..

    ..:: Free Radical ::.. Well-Known Member

    Hey, my 8 year old UPS just croaked. It was a good thing I searched the forums for reviews. Please suggest me the cheapest pure sine wave inverter from APC. backup time is not an issue(even 5 minutes will do) as I rarely get power cuts and even if i do, i turn off my computer asap. I need one with reliable output, surge/spike/earthing/overvoltage/undervoltage protection.

    Please keep in mind that I am contemplating a Crossfire setup with the 4850s on a TX750 with a bunch of hard disks. So I need headroom.
  15. Spectre

    Spectre Well-Known Member

    Nice article...:)
  16. VanishingNerd

    VanishingNerd New Member

    The APC SmartUPS 750VA is the cheapest and it will give you 500W Peak with nearly 5 min of backup. I can run some tests if you want. I have it right now. Got it for 9k vat, shipping included straight from the distri.

    Thing is a CF setup will need close to 400W, add 50W for LCD and another 20-150W depending on what speakers you are using, although you can keep the speakers off the UPS as you are not looking for backup anyway.
    1 person likes this.
  17. Techie#1

    Techie#1 Well-Known Member

    Firt of all... Sorry for bumping up a OLD thread, but i think, i have a important question pertaining to this issue?

    Is the above Simulated NON-pure Sinewave that much of the UPS & Invertors generate, also popularly called a "Quasi-sine wave"???

    I need to know,'coz i have a Digital invertor running for the last 5 + years which the company describes as a Quasi-wave invertor. the Model is USHA Zentra Digital Inverters-model HUPS 1400VA(refer here- http://www.ushainternational.com/pro_invertor_zentra_digital.html).I input it to my 800VA Numeric UPS(which also produces a Quasi-Sinewaveform) & which goes to power my PC through the 500W L&C(Powersafe-KPL) SMPS(model- LC-B500E).
    I think the L&C does NOT have Active PFC, so it runs under the said condition for hours together during power-outage through all these years.
    However some conditions r noticeable, slight noise/hum does emits from the PC & the monitor SOMETIMES flicker too even in 85+hz rr's(Using 19' CRT).

    So was just wondering, whether, this is a safe Process of using the PC & the accessories-the CRT monitor,etc, when the Pure-sinewave AC powersupply in NOT available from the regular supply board, during the long hours of power-outage,particularly during the Hot sumers???

    I'm just a laymen-skeptic,w/o much technical depth.So If the experts here answers my question, i would be VERY MUCH thankful & better prepared!
  18. shadow2get

    shadow2get Well-Known Member

    I was doing a research on UPS & Inverters (planning to buy both - for Comp & House respectively). The information which I got from Tom's Hardware Forum was easy to understand, explaining the various electrical/electronic terminologies wrt UPS & Inverters. Thought I would share it with you guys.

    Click the link below for a detailed explanation
    UPS Related FAQ

    The forum member,SomeJoe7777, who made the post there has created a comparison chart of different UPS brands & models for fast reference. Check it out below:


    Note: If possible, mods/thread starters could put this image in the first post of this thread for easy reference to everyone.
  19. akiso

    akiso New Member

    I have rig which would consume 525W-560W, but with full load and +1year time period (considering the ageing capacitor) it is to consume 671W at full load. So what UPS would you suggest?
    Apart from APC is there any option. And also do I have to consider the SMPS when I buy the UPS so that it is supported by the UPS and I get full output.
  20. Rockfella

    Rockfella Senile.
    Section Mod

    Informative thread!!

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