1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

UPS and Voltage Question

Discussion in 'DIRECTV HD DVR/Receiver Discussion' started by john18, Mar 4, 2007.

Thread Status:
Not open for further replies.
  1. Mar 4, 2007 #1 of 12
    john18

    john18 Active Member

    1,035
    11
    Nov 21, 2006
    It is fairly well established that the home entertainment center, including the HR20, is well served by having a good UPS and good voltage regulation providing power to the DVR's and more expensive display units. The one I purchased is supposed to supply very clean power at a very constant 120v.

    My UPS has a display that shows the voltage coming in, and it is usually 117-120v, but I have seen it as low as 114v. It also claims that it provides the 120v power without using the battery unless the voltage drops below approx 87v. The question is how does it raise the voltage without using battery power?

    Thanks in advance for any replies.

    John
     
  2. Mar 4, 2007 #2 of 12
    veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

    42,679
    348
    Dec 9, 2006
    Large capacitors, or it doesn't & it's marketing....
     
  3. Mar 4, 2007 #3 of 12
    hasan

    hasan Well-Known Member

    5,957
    54
    Sep 22, 2006
    Ogden, IA
    Any good UPS uses a switching supply which tolerates undervoltage quite well. Since the DC input is driving an oscillator (which keeps running under widely varying input voltages), the output can be maintained with relatively "normal" sized filter capacitors. Switching supplies have very good source voltage tolerance by design. Their output is much "dirtier" (non-sine wave), but they hold voltage nicely.

    (This is all only when the UPS is "running", i.e., commercial power is absent. When normal power is supplied, unless you purchase a "line conditioner" type UPS (very expensive for decent ones), the UPS isn't doing anything other than line filtering and some surge protection.

    My UPS's saved the day many, many times in the last 10 days. Lots of power outages, some long, some only winkies...nastly line spikes...really icky stuff. The UPSs did their job nicely, protecting everything in the HT rack as well as my 56" Sammy DLP. They are all APC 1100 watt models of one variation or another.
     
  4. Mar 4, 2007 #4 of 12
    Dawn Knight

    Dawn Knight Mentor

    42
    0
    Feb 22, 2007
    Your SmartPro 1500LCD uses "Automatic Voltage Regulation" which runs all the time, even when commercial line power is present, not just when the battery takes over. It accomplishes this by powering all its outlets from its internal switching supply at all times. The switching supply is capable of maintaining a constant voltage output under a wide range of input over- and under- voltage conditions.
     
  5. Mar 4, 2007 #5 of 12
    armophob

    armophob Difficulty Concen........

    7,393
    65
    Nov 13, 2006
    Fort Pierce, FL
    I have 13 APC UPS units running in my house. Nothing except large appliances is without one. It is not the surges that kill us here in Florida, its the brown outs. You never see them coming. Lights don't dim, but every now and then, all the backups beep. And then I know I just saved my equipment once again.
     
  6. Mar 4, 2007 #6 of 12
    hasan

    hasan Well-Known Member

    5,957
    54
    Sep 22, 2006
    Ogden, IA
    Florida and Iowa...both big T-boomer states, and we get blizzards while you get hurricanes. UPS heaven!

    The solitary "beep" incident is what we call a "winkie" up here.

    It's this simple: if you care about the equipment you use, then put it on a UPS. In our environment, running anything of value without a UPS is playing Russian Roulette.
     
  7. Mar 4, 2007 #7 of 12
    john18

    john18 Active Member

    1,035
    11
    Nov 21, 2006
    Thank you everyone.
     
  8. Mar 5, 2007 #8 of 12
    w6fxj

    w6fxj DBSTalk Club Member

    311
    0
    Aug 10, 2005
    John

    The Trip-Lite Smart 1500LCD regulates input AC power by selecting between four different taps on the output transformer depending on the voltage. There are two lower voltage taps and one higher voltage tap. When the input voltage is between 75 and 92 VAC, the tap boosts the voltage by 30%. When the input is between 93 and 107 VAC, it boosts 14%. Between 108 and 127 VAC there is no change. Between 128 and 147 (or above) the output voltage is reduced by 12%. The battery-powered switching inverter is NOT used unless the input voltage goes below 75 VAC. (see the Trip-Lite specs here: http://www.tripplite.com/products/product.cfm?productID=3151#spec)

    Bill
     
  9. Mar 5, 2007 #9 of 12
    rlnoonan

    rlnoonan Legend

    126
    0
    Jan 5, 2007
    I have an APC J10 which says it does pretty much the same thing. I wondered the same thing myself about how it raises the voltage. I assumed it is able to do this because you have more amps coming in than you are using (going out), so you have excess power available. That's how it can charge the capacitors used to pump up the voltage (I guess).

    At my home the voltage is usually 126 - 130V and the APC does bring it down, but usually only to 122 - 124V, not 120V constant. Not really sure why, but I figured that was close enough and not going to cause any long term problems. Also, every once in a great while when I turn on my system, the APC will switch to the battery for a second or so. It is like the initial surge of all the equipment turning on makes the APC think a brownout has occurred or something like that. Any one else ever have that happen?

    Bob
     
  10. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

    42,679
    348
    Dec 9, 2006
    You can't charge capacitors with amps. They're a "voltage thing". Transformers will though.
    The boot "drop off" of your UPS [made by APC] is [I think] because the load [surge] exceeds the output of your UPS.
     
  11. john18

    john18 Active Member

    1,035
    11
    Nov 21, 2006
    So when they are talking about providing clean power they are talking about spikes, surges and lags and when I am showing that I am getting 117v in the unit is not really doing anything to the power at that point except constantly monitoring it in case it drops off to below 108v or rises above 127v?
     
  12. Dawn Knight

    Dawn Knight Mentor

    42
    0
    Feb 22, 2007
    The unit is always monitoring for and protecting against spikes and surges, which is how it keeps the output "clean".
     
Thread Status:
Not open for further replies.

Share This Page