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Interesting discussion on energy consumption

Discussion in 'DIRECTV General Discussion' started by Thaedron, Jun 27, 2011.

  1. gitarzan

    gitarzan Godfather

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    Refridgerators became much more efficeint around year 2001. When I had a Dish VIP622 I found it using quite a bit more electricity than my 17.8 cubic ft Fridgidarie. I found the more recent DirecTV DVR's to do much better.
     
  2. ticmxman

    ticmxman Legend

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    Last month I picked up a device at Home Depot for $25 the I've been using to monitor my electricity cost on a old refrigerator and a old freezer. It breaks it down cost per hour,day, month, year. The old stuff uses about twice as much as my new frige. It is a handy tool and if nothing else it makes me think about what can be turned off, unplugged or eliminated. Next I'll be checking the DVRs. But for the convienance I get out of using my DVRs it doesn't matter much to me, they are worth it. The way I look at it if I have no DVR then I have no need for a pay tv provider at all, just get my signal OTA for free. Not that I watch much TV when I travel but when I do live TV drives me nuts.
     
  3. Rich

    Rich DBSTalk Club DBSTalk Club

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    Might be local or NEC codes that require a 20 Amp dedicated line for a refrigerator. Dedicated in this case means nothing else on that particular circuit. If you looked at an ammeter when the compressor comes on you'd see a spike that would rapidly disappear as the compressor motor comes up to speed. Happens with all motors.

    Rich
     
  4. P Smith

    P Smith Mr. FixAnything

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  5. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    actually I think "big capacitors" are used to reduce this.
    Motor "stall current" is the surge, which gets reduced as they spin up.
     
  6. Go Beavs

    Go Beavs Hall Of Fame

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    "Big capacitors" are used to increase the power factor on induction motors. The surge during start comes from the resistance in the motor windings being close to zero when stopped, so it acts like a short across the windings. The resistance increases as the motor comes up to speed.
     
  7. P Smith

    P Smith Mr. FixAnything

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    Is it 'actually' or 'I think' ? Riding two horses ?:D
     
  8. ThomasM

    ThomasM RF Engineer

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    My refrigerator (A Frigidaire purchased in 2009) takes 100 watts when it is running. It runs for about an hour and then shuts off for about two hours (if the door remains closed). So that's about 8 hours of running a day-let's say 10 hours a day since I do open the door once in awhile. ;)

    OK, that's ONE kilowatt hour per day (100 watts x 10 hours).

    MEANWHILE, my DirecTV DVR's (both R15 SD and R22 HD) take about 25 watts CONTINUOUSLY. That's 75 watts (I have 3 DVR's) x 24 hours or 1.8 kilowatt hours....almost TWICE what my refrigerator uses.

    Now, the refrigerator has to keep the food cold so it has to be on all the time, but the DVR's don't. With the present guide caching scheme, they could EASILY power their hard drives down when they are in standby and nothing is scheduled to be recorded. (Similar to a computer in hibernate mode). Heck, my old RCA DirecTV box had a 7 day program guide and it didn't even HAVE a hard drive!!

    I power down 2 of my 3 DVR's each weekday during the electric company's "on peak" time period, and when I power them back up ALL 14 DAYS OF GUIDE DATA is there waiting for me. Granted, there is no live buffer but most of the time the live buffer is buffering a different channel than the one you left current when you placed the unit in standby anyway...
     
  9. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    "I think" they're big caps, but someone else might not. ;)
     
  10. P Smith

    P Smith Mr. FixAnything

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    I did a lot of tests working with power supplies, PMIC, etc, so the inrush current and its source I know from roots...
     
  11. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Power supplies aren't quite the same as motors.
     
  12. TDK1044

    TDK1044 Godfather

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    I have three HD DVRs and two LCD 46 inch flat screen TVs, as well as an i-pad, two Laptops and a Desktop computer. My power bill each month is just under $100. What's the big deal?
     
  13. Rich

    Rich DBSTalk Club DBSTalk Club

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  14. P Smith

    P Smith Mr. FixAnything

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    Are we talking about 3-phase motors ? Nope - home refrigerator's guts.
     
  15. Rich

    Rich DBSTalk Club DBSTalk Club

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    Think of it as wanting to keep an empty bucket with a small hole in it full of water. You "rush" the initial flow to get it filled and then throttle back to keep it filled.

    On motors, caps are usually used in place of start windings to "kick start" the motor. Cheaper than a separate start winding. We used cap start motors on a lot of pumps that needed that initial kick to get the material moving. High torque motors.

    You will always see an initial spike of current on a motor's amp guage, then it reaches it's rated speed and the current settles into the rated amperage.

    Rich
     
  16. P Smith

    P Smith Mr. FixAnything

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    Principles are still the same - during the initial change of voltage the capacitance is responsible for inrush current.
     
  17. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    For Mr Smith it does, in relation to power supplies, but not with motors.
     
  18. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    In the link you added, inrush current is explained/defined well.
    "Point being" motors are different than power supplies, though both have inrush current.
    Power supplies need to charge caps, while motors need to have the fields stabilize
     
  19. Rich

    Rich DBSTalk Club DBSTalk Club

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    He's gotta realize that inrush current is part of every electrical device. You have to fill the bucket first.

    Rich
     
  20. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    "I think" he was simply focused on his experience, but should realize it happens to everything.
    Even a wire, not connected to anything, will have inrush current when power is applied.
     

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