# Interesting discussion on energy consumption



## Thaedron (Jun 29, 2007)

I ran across the following earlier today:

http://hardware.slashdot.org/story/11/06/27/044231/DVRs-Cable-Boxes-Top-List-of-Home-Energy-Hogs

and the originally referenced article:

http://www.nytimes.com/2011/06/26/us/26cable.html?_r=4

While some of the claims int he article seem a bit over-blown... There certainly are things that could be done to trim the energy usage within the modern DVR without seriously impacting the user experience.


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## pfp (Apr 28, 2009)

I've seen a couple articles talking about this recently. There people obviously don't understand the function of a DVR if they think it can work as designed completely powered down.


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## P Smith (Jul 25, 2002)

Thaedron said:


> I ran across the following earlier today:
> 
> http://hardware.slashdot.org/story/11/06/27/044231/DVRs-Cable-Boxes-Top-List-of-Home-Energy-Hogs
> 
> ...


Do wee need second thread about same subj ? http://www.dbstalk.com/showthread.php?t=194335


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## curt8403 (Dec 27, 2007)

as I recall from a few years ago, Directv units (DVRs included) were designed to be more energy friendly than some other units on the market.


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## Rich (Feb 22, 2007)

pfp said:


> I've seen a couple articles talking about this recently. There people obviously don't understand the function of a DVR if they think it can work as designed completely powered down.


Didn't the Ultimate TV DVRs power completely (or almost completely) down and then come back up when they needed to record something? Was a long time ago that I had them and I'm not sure about this. Anybody remember? I've never understood why they can't power almost completely down when not in use. Down to, say, 3W?

Rich


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## hilmar2k (Mar 18, 2007)

P Smith said:


> Do wee need second thread about same subj ? http://www.dbstalk.com/showthread.php?t=194335


That one is on the Dish side. I don't read or follow any of those threads, so having this one does not seem redundant.


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## Avder (Feb 6, 2010)

One thing that would save power is if the thing wasnt thrashing the disk all the time when its supposedly turned off. An option for a low power mode where nothing but the scheduler and the clock are operating would be nice too. Discard all tuner buffers, shut the disk off, power down the tuners and do nothing but wait for a scheduler command or the user to turn the thing back on.

You know, an actual standby mode.


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## DogLover (Mar 19, 2007)

Since portions of the guide data are continually being downloaded from the satellite, then a true standby mode would have the problem that portions of the guide data would not be updated. While some customers mint be okay with that, some would undoubtably complain when things were not recorded properly, because of a change in guide data.


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## veryoldschool (Dec 10, 2006)

DogLover said:


> Since portions of the guide data are continually being downloaded from the satellite, then a true standby mode would have the problem that portions of the guide data would not be updated. While some customers mint be okay with that, some would undoubtably complain when things were not recorded properly, because of a change in guide data.


I'm sure some of the hardware could be powered down more than we have now.
The guide has its own tuner, so the other tuners could be turned off.
Now they would still need to power the LNBs [on non SWiM systems] to receive and commands/data, which may mean they'll still use say 10 watts.
Given that the DVRs use 20 [something] to 37 watts [standby], while saving anything isn't a bad idea, a couple of CFLs seems like they would offset this usage.


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## jdspencer (Nov 8, 2003)

And what about the Power Inserters used for powering the SWM LNB and the DECA modules. etc. 

Then there are the cable/DSL modems and routers. If you want to get to the nitty gritty, you have TVs that use some power waiting for a remote command to turn on. You could list a whole bunch of power consuming equipment in the home. Anyone still have an analog clock plugged in?


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## Skyboss (Jan 22, 2004)

SSDs.... Not quite yet, but eventually they will leave HDs in the dust on energy consumption.


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## pfp (Apr 28, 2009)

With live buffering you also have a hard drive constantly spinning and writing.


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## pfp (Apr 28, 2009)

Skyboss said:


> SSDs.... Not quite yet, but eventually they will leave HDs in the dust on energy consumption.


I would think the limited writes of an SSD would be problematic for a DVR which is continuously writing data to the drive.


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## Alebob911 (Mar 22, 2007)

Like VOS says, convert to CFL or LED lighting and call it good. I had my Kill-A-watt attached to my HR and what it uses with the power light off was nothing as far as I was concerned. I think it was in the 12-14 watt area. I have all CFL or LED lighting so I am green when it comes to lighting. To me it just seems petty to pick on DVR's has the big electricity monster. If they didn't work on lowering the power usage with new models then pick on them but I think they have been doing a great job in becoming more energy efficient. It takes time to engineer a solid more energy efficient product.


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## dennisj00 (Sep 27, 2007)

While more recent chip designs have 'sleep' modes for certain subsystems, I doubt the current H/HR series have the ability to sleep individual subsystems like tuners, etc. Even stopping the hard drive would require a complete revamp of handling guide data and todo calculations.

Lowering or raising (depending on the season) your heating / cooling temps by a couple of degrees and changing to CFLs / LEDs would have a much bigger impact.


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## veryoldschool (Dec 10, 2006)

From here: http://reviews.cnet.com/green-tech/tv-power-efficiency/


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## astrotrf (Apr 5, 2004)

> DirecTV HR20 DVR: 33 watts

Something's not right here -- that's a kilowatt in 30 hours, which costs me ten cents. That works out to $2.40 for a month, not the $10 of the referenced article. Does anybody really pay 40 cents per kilowatt-hour?

I can't really get excited up about less than $30 of electricity for an entire year. OTOH, I should reveal my biases: "People in the energy efficiency community" mostly just give me a ruddy shootin' pain, anyway, what with telling me to unplug my two-dollars-per-year wall warts, etc. My solution to their making me wait 30 seconds for my TV to warm up and show a picture (gotta get rid of that awful instant-on stuff) was simply to leave the thing on. They want me to sacrifice my convenience to soothe their sensibilities -- so I just say no.


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## admdata (Apr 22, 2011)

For my $.05 worth, if they can have the tech in england to power down and up there STB's why not here??, I mean was other's were saying, ok so Directv STB's receive guide data all the time 24/7, most STB's store 14 days (DVR's) and 3.5 days for the SD receivers, if you power down the unit over night (no recording are there), then in the morning you turn on the STB to watch the local news, why not have it that the STB will update the guide data when it is on and running and play catch up, hell Dish's boxes reboot at 3am (Local time) and redownload there guide data in one shot, granted it is either 3 days (for the basic receivers, or 7 days for there DVR's), the tech is out there it is all about the willingness of companies to use it!

Yes I have upgraded all my lighting in my house to CFL's or Florescent bulbs and it has saved me a bundle, I also have my outdoor lights on timers, after doing the above I saved $60 a month on electric.


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## Stuart Sweet (Jun 19, 2006)

This seems to be the big story this week. 

It's worthwhile to note that the DIRECTV HD DVRs are Energy Star certified and most other DVRs are not. 

Also worth noting that if these devices went into standby when not explicitly being used, energy use would drop but you would never have a buffer when you turned on the TV.


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## ShapeGSX (Sep 17, 2006)

Stuart Sweet said:


> Also worth noting that if these devices went into standby when not explicitly being used, energy use would drop but you would never have a buffer when you turned on the TV.


I think that for some people that would be an acceptable trade off. Not to mention that the hard drive would be silent (great for bedrooms), and the hard drive would likely last a lot longer. They should make it an optional setting if the hardware can handle it.


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## ThomasM (Jul 20, 2007)

I have "time of use" electricity pricing. At night & on weekends, I pay less than 5c per kWh but during weekdays (7AM-7PM) it's over 25c. After doing a little number crunching, I discovered that an R15 and my R22 sucked up over five bucks a month in electricity by being on during the weekday "peak" period even though I didn't record or watch anything then. I do all my daytime recording/watching on my third DVR (also an R15).

So TWO YEARS AGO I equipped my R22 and one R15 with one of those switches that plug into the wall outlet and a cord plugs into them. Every weekday morning at 7AM the two DVR's get flipped off and every evening just before 7PM (the start of prime time) they get flipped back on.

The DVR's don't seem to give a hoot, and thanks to guide caching, when they power up there is my 14 day program guide.


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## Nick (Apr 23, 2002)

hilmar2k said:


> That one is on the Dish side. I don't read or follow any of those threads, so having this one does not seem redundant.


This topic should be in a general thread anyway. The subject of energy usage in DVRs should not be restricted to just one provider, be it Directv, Dish or cable.


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## Rich (Feb 22, 2007)

Nick said:


> This topic should be in a general thread anyway. The subject of energy usage in DVRs should not be restricted to just one provider, be it Directv, Dish or cable.


Do you know how much wattage a Dish DVR uses? Always been curious about that.

Rich


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## admdata (Apr 22, 2011)

rich584 said:


> Do you know how much wattage a Dish DVR uses? Always been curious about that.
> 
> Rich


Don't quote me 100%, (my parents have SD dish network on HD tv's) they have a Duo 322 (SD revicer) for 2 HD tv's and a Duo DVR 625 (for 2 SD tv's) I think that the Duo 322 uses 35-40 watts, not sure about the DVR. Next time I am over there I will check and let everyone know!


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## TomCat (Aug 31, 2002)

Avder said:


> One thing that would save power is if the thing wasnt thrashing the disk all the time when its supposedly turned off. An option for a low power mode where nothing but the scheduler and the clock are operating would be nice too. Discard all tuner buffers, shut the disk off, power down the tuners and do nothing but wait for a scheduler command or the user to turn the thing back on.
> 
> You know, an actual standby mode.


I never had a thrashing or noisy HDD in the 15 or so different DVRs I've had since 1998, so I can't speak to that problem, but its not just the scheduler and clock (a clock can run on a CMOS at very tiny voltages for weeks, BTW). It is also all of the background indexing, and you need at least the 5v supply to be up for any CPU work to get done.

If you figure 300 channels (probably a low estimate) and each sheduling 35 programs a day, we are talking over 10,000 shows each day, each of them with numerous elements of metadata (figure how much data there is just for the cast and crew metadata). And when you have multiple data points for other multiple data points, you are talking possibly a million data points daily, maybe more. Now you have to maintain a database that goes back 28 days and forward another 8 or 9, not to mention the history which goes back to the day it was installed. Now we are talking up to 50 million data points.

The only way to search that data quickly is to index it first, which means creating a new data point for every combination of multiple data points representing any possible filtered search, which does most of that potential work ahead of time so that when you do search, it responds with results within a reasonable time frame.

If you did not index, it would expand the time by an order of magnitude (IOW, 50 million becomes 50 million _times_ 50 million) because groups of data points cant be searched at the same time, only serially, and if you filter, you have to search by every aspect of that filter in serial order (for the show "This Old House" it first has to search for terms that start with "T" followed by those in that subset that next have the letter "h", followed by those in that subset that next have the letter "i", etc., etc. You can't search for all of those data points simultaneously, so indexing creates a single data point to represent every combination of possible data points, and when you search, you search for that single data point, which expands the DB substantially but speeds the search dramatically.)

And indexing takes time, and there is a lot of it to do, more every time a data dump happens from the sat. Consequently, your DVR is busier than a server at SETI, and having it churn all of this data in the background nearly 24/7 is actually sort of necessary.

I technically manage a collaborative workflow environment (Avid Interplay) for a professional broadcast news operation that has a media storage network of 42 TB, with about 1.5 TB of that being changed out daily through a hundred different clients. It takes three dedicated 64-bit quad-core enterprise-class Intel 2500 servers churning on all cylinders to keep up with _just the indexing _needed for that system. Your DVR does much the same thing, only on a smaller scale.


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## Tom Robertson (Nov 15, 2005)

Remember, there ain't people paying for the research into reducing power usage. Few, very few people will do to DIRECTV just because DIRECTV receivers use less power. Most people will look at their monthly TV bill, not their monthly TV bill plus their monthly electric bill.

And also remember that there are over 2,000 channels worth of guide data right now. Ever local, every subchannel OTA, every national channel is a LOT of guide data. While the DVRs don't have to index all of that data (only the data that pertains to the users location), they do have to receive all that data.

And the receiver needs to periodically receive it's authorization to decode the video streams. Miss that auth code too often and users start calling in for resets. And that gets VERY expensive to DIRECTV and very annoying for customers.

So every subsystem needs to be researched and tested before power savings can be applied in standby. And that costs money...

As for DIRECTV, many of their receivers qualify for the Set Top Box Version 2 EnergyStar specifications. In fact, it might be all of the currently manufacturing receivers. 

And some of their current units might already qualify for the Version 3 specs that start September 1. 

Cheers,
Tom


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## Tom Robertson (Nov 15, 2005)

veryoldschool said:


> From here: http://reviews.cnet.com/green-tech/tv-power-efficiency/


Alas, as we all really know, the moment to moment power draw is not the only factor in cost of an item for a year. A TV might be 10 times the draw of a receiver (and many are now down to only 3 times) but a receiver is on all the time and a TV is off roughly half the time.

Cheers,
Tom


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## RobertE (Jun 10, 2006)

Tom Robertson said:


> And also remember that there are over 2,000 channels worth of guide data right now. Ever local, every subchannel OTA, every national channel is a LOT of guide data. While the DVRs don't have to index all of that data (only the data that pertains to the users location), they do have to receive all that data.


Just going to comment on this part. I believe this is a serious flaw in the way DirecTv handles its guide data and plays a significant part in the speed (or lack of) of the receivers.

There really is no valid reason that my HD DVR, needs to constantly get local guide data for every other market out there. It has to do something with all that data. Either filter it out from the get go, or process it and hide it from the user. Either way, it's a waste of processor time and power.

Local guide data should be confined to the spotbeam of said local channel.


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## Tom Robertson (Nov 15, 2005)

RobertE said:


> Just going to comment on this part. I believe this is a serious flaw in the way DirecTv handles its guide data and plays a significant part in the speed (or lack of) of the receivers.
> 
> There really is no valid reason that my HD DVR, needs to constantly get local guide data for every other market out there. It has to do something with all that data. Either filter it out from the get go, or process it and hide it from the user. Either way, it's a waste of processor time and power.
> 
> *Local guide data should be confined to the spotbeam of said local channel.*


Requiring another tuner constantly tuned to your local spotbeam...

The filtering should be fairly simple on the whole of the system.


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## P Smith (Jul 25, 2002)

Tom Robertson said:


> Requiring another tuner constantly tuned to your local spotbeam...
> 
> The filtering should be fairly simple on the whole of the system.


You guys so freely speculating, I can't hold my breath ...

Gct posted PDF files shows how the guide [APG] spread thru 101W tpns.

Only 101W used for LiL.

[Last posts are way of reality doing speculation how often FW serve APG,DB, idx, etc.]


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## veryoldschool (Dec 10, 2006)

P Smith said:


> You guys so freely speculating, I can't hold my breath ...
> 
> Gct posted PDF files shows how the guide [APG] spread thru 101W tpns.
> 
> ...


You're so "SD"....
Some of those even come from 119 still, while our HD come off 99 or 103.


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## Upstream (Jul 4, 2006)

Tom Robertson said:


> but a receiver is on all the time and a TV is off roughly half the time.


Your TV is on 12 hours a day?


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## Tom Robertson (Nov 15, 2005)

Upstream said:


> Your TV is on 12 hours a day?


often times. 

The EnergyStar people have equations they've standardized to calculate total energy based on the device family and if it has automatic shutdown/sleep.

Cheers,
Tom


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## RunnerFL (Jan 5, 2006)

Avder said:


> One thing that would save power is if the thing wasnt thrashing the disk all the time when its supposedly turned off. An option for a low power mode where nothing but the scheduler and the clock are operating would be nice too. Discard all tuner buffers, shut the disk off, power down the tuners and do nothing but wait for a scheduler command or the user to turn the thing back on.
> 
> You know, an actual standby mode.


But then you'd have people complaining that the channel they want to watch in the morning wasn't buffered overnight. And, as DogLover pointed out, your guide data wouldn't be updated.


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## RunnerFL (Jan 5, 2006)

admdata said:


> For my $.05 worth, if they can have the tech in england to power down and up there STB's why not here??, I mean was other's were saying, ok so Directv STB's receive guide data all the time 24/7, most STB's store 14 days (DVR's) and 3.5 days for the SD receivers, if you power down the unit over night (no recording are there), then in the morning you turn on the STB to watch the local news, why not have it that the STB will update the guide data when it is on and running and play catch up, hell Dish's boxes reboot at 3am (Local time) and redownload there guide data in one shot, granted it is either 3 days (for the basic receivers, or 7 days for there DVR's), the tech is out there it is all about the willingness of companies to use it!


Holy run on sentences Batman....

In all seriousness though... People complain about poor performance of the DVRs now while they download and update guide data after a flush. Can you imagine the complaints if there were a daily "catch up"?


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## Tom Robertson (Nov 15, 2005)

DIRECTV is very capable of finding ways to save energy. They are plenty smart enough to re-engineer how the guide is downloaded, how the receivers are authorized, how the receivers index things in various modes (full power, half power, etc.), which subsystems can be turned off, etc.

DIRECTV is also smart enough to handle the economics correctly. Re-engineering all these things takes money. (In some cases, lots of money as they need to verify the changes with a great many receivers.) And DIRECTV can't start charging customers a "$1 EnergyStar Recovery Fee" to pay for the changes.

So DIRECTV _may_, I do not know for certain, continue to slowly put energy saving features into the receivers. Perhaps to meet EnergyStar 3 specifications.

Other companies seem to not care at all. They don't have any receivers on the EnergyStar list right now.

Cheers,
Tom


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## P Smith (Jul 25, 2002)

veryoldschool said:


> You're so "SD"....
> Some of those even come from 119 still, while our HD come off 99 or 103.


I'm responding/talking about LiL APG, not 110/119/95 - yes, those sats (110/119/95 and 72.7/GLA if you want whole picture) carry each own guide data. Just see that gct's PDF.

As to HD [MPEG-4], those channels (audio and video streams) coming from 99/103 and 119 WITHOUT guide data.


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## veryoldschool (Dec 10, 2006)

Tom Robertson said:


> So DIRECTV _may_, I do not know for certain, continue to slowly put energy saving features into the receivers.
> 
> Cheers,
> Tom


So by "evolution" instead of "revolution".


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## technicholas (Jul 2, 2011)

Those HD DVR's use LOTS of power more then my fridge


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## NR4P (Jan 16, 2007)

technicholas said:


> Those HD DVR's use LOTS of power more then my fridge


Have you checked your fridge when the compressor is running?
My current home and last home came with 20amp service on the refrigerator outlet. That puppy pulls alot of amps to start that compressor.


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## gitarzan (Dec 31, 2005)

technicholas said:


> Those HD DVR's use LOTS of power more then my fridge


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.


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## ticmxman (Aug 28, 2007)

gitarzan said:


> 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.


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.


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## Rich (Feb 22, 2007)

NR4P said:


> Have you checked your fridge when the compressor is running?
> My current home and last home came with 20amp service on the refrigerator outlet. That puppy pulls alot of amps to start that compressor.


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


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## P Smith (Jul 25, 2002)

It has a name  - Inrush current (because of big capacitors).

To cut speculations, just read first paragraphs of the document: http://www.aemc.com/techinfo/appnotes/clamp_on_meters/App_Clamp-OnMeters_InrushCurrent.pdf


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## veryoldschool (Dec 10, 2006)

P Smith said:


> It has a name  - rush current (because of big capacitors).


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


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## Go Beavs (Nov 18, 2008)

"veryoldschool" said:


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


"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.


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## P Smith (Jul 25, 2002)

veryoldschool said:


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


Is it 'actually' or 'I think' ? Riding two horses ?


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## ThomasM (Jul 20, 2007)

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...


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## veryoldschool (Dec 10, 2006)

P Smith said:


> Is it 'actually' or 'I think' ? Riding two horses ?


"I think" they're big caps, but someone else might not.


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## P Smith (Jul 25, 2002)

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


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## veryoldschool (Dec 10, 2006)

P Smith said:


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


Power supplies aren't quite the same as motors.


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## TDK1044 (Apr 8, 2010)

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?


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## Rich (Feb 22, 2007)

P Smith said:


> It has a name  - Inrush current (because of big capacitors).
> 
> To cut speculations, just read first paragraphs of the document: http://www.aemc.com/techinfo/appnotes/clamp_on_meters/App_Clamp-OnMeters_InrushCurrent.pdf


It's got nothing to do with capacitors. Three phase motors don't use capacitors and they experience the same inrush current every electrical device does.

Rich


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## P Smith (Jul 25, 2002)

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


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## Rich (Feb 22, 2007)

veryoldschool said:


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


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


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## P Smith (Jul 25, 2002)

veryoldschool said:


> Power supplies aren't quite the same as motors.


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


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## veryoldschool (Dec 10, 2006)

rich584 said:


> It's got nothing to do with capacitors. Three phase motors don't use capacitors and they experience the same inrush current every electrical device does.
> 
> Rich


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


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## veryoldschool (Dec 10, 2006)

P Smith said:


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


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


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## Rich (Feb 22, 2007)

veryoldschool said:


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


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

Rich


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## veryoldschool (Dec 10, 2006)

rich584 said:


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


"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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## TBoneit (Jul 27, 2006)

ThomasM said:


> 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.


Except to be fair you need to compare one DVR to one refrigerator. in my opinion of course.

We can't all afford to go out and replace working appliances. I replaced the Washer and Drier and 2 wall mount AC units over the last two years because they would cost more to fix than repair, not to save energy. Fortunately they died far enough apart that I could rebuild reserves between.

I also need to buy a case of Incandescent light bulbs for a family member that hates CFLs before they become hard to buy.


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## P Smith (Jul 25, 2002)

Well, you can think as you wish ...

[I would stick with physical law, formulas and experience. BTW, those devices what I mentioned wasn't power supplies, but devices what creates load to them, and the inrush current too.]

:backtotop:


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## veryoldschool (Dec 10, 2006)

P Smith said:


> Well, you can think as you wish ...
> 
> [*I would stick with physical law, formulas and experience*. BTW, those devices what I mentioned wasn't power supplies, but devices what creates load to them, and the inrush current too.]
> 
> :backtotop:


I don't know of any way to escape them. 
Caps have nothing to do with an inductive circuit, which also has inrush current.


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## P Smith (Jul 25, 2002)

There are ways to make 'soft start' - new PMIC has it.

Regarding transformers and motors ( the part is not my cap of tea), re-reading other source I got the point, - how inrush current happening there: 
At 0 voltage, there is no inductance, so only a resistance of winding is limiting current ...


> Transformers and other inductive circuits behave in a manner that is not intuitive. Should the power be applied at zero volts (the zero crossing point), this is the very worst case. The core saturates, and peak current is limited by one thing only - circuit resistance. Since a 500VA toroidal transformer will have a typical primary resistance of around 4 ohms (2 ohms for 120V countries), the worst case peak current is determined by ...
> 
> IP = VP / R
> IP = 230 * √2 / 4 = 325 / 4 = 81A
> ...


http://sound.westhost.com/articles/inrush.htm


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## veryoldschool (Dec 10, 2006)

Motors "I think" can be just a bit more complex [than a transformer], mainly due to spinning up to speed.
Some have cap starter to change the phase.
Sometime back, the company I worked for, used some of their talent and found adding a cap to all 1/2 HP, and greater, motors would save energy. I've forgotten the cap value.
The armature and the field coils have an optimum phase relationship, which is only at one speed.


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## Rich (Feb 22, 2007)

veryoldschool said:


> "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.


I got that from his posts. I think. I don't know how many of the folks reading this thread understood his example of the transformer, but I did and it's a perfect example of inrush current. While the inrush current in that example is higher than most devices would allow, it's not uncommon for this to happen. That's what fuses are for and transformers usually have fuses that prevent this from happening.

In a three phase motor, the inrush current is usually ten times the running current, but that's allowed by time-delay fuses that take that inrush current for a brief time and don't blow. The inrush current is usually equal to locked rotor current and the time delay fuses do blow when the rotor is locked.

He also uses the term "0 Voltage". I would take issue with that. I don't think there is such a thing. Voltage doesn't move in the sense that current does. You have to induce it and the term "0 Voltage" is not possible once the induction process begins. When the induction process begins the voltage is instantaneously induced. I guess you could make the argument that voltage starts a 0 Volts, but that implies movement of voltage and that's not possible. Your car will go from 0 to 60 in X seconds, but the car moves, so 0 is a valid starting point. Since voltage doesn't move, I don't see how 0 Voltage can be a valid term.

I'm gonna stop this argument now. I didn't Google any of my argument, it's all off the top of my head. Mr. Smith may now reply. I do realize this has nothing, or almost nothing, to do with refrigerators or DVRs, but I do find it interesting.

Rich


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## veryoldschool (Dec 10, 2006)

rich584 said:


> He also uses the term "0 Voltage". I would take issue with that. I don't think there is such a thing. Voltage doesn't move in the sense that current does.
> 
> Rich


0 Voltage is when the sine wave crosses from positive to negative, so it is a degree in the phase of the wave.
You're a "power guy", while I'm an "RF guy", so I'll need to explain from much higher frequencies:
Power is constant in a transmission line, so if P = V x A, when voltage is max, current is min, and if current is max, voltage is min.
If you look at this in a "sine wave mode", in one plane is a voltage sine wave and at 90º to this plane is another plane with a sine wave of current. This current sine wave is also 90º out of phase with the voltage sine wave.


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## Rich (Feb 22, 2007)

veryoldschool said:


> 0 Voltage is when the sine wave crosses from positive to negative, so it is a degree in the phase of the wave.
> You're a "power guy", while I'm an "RF guy", so I'll need to explain from much higher frequencies:
> Power is constant in a transmission line, so if P = V x A, when voltage is max, current is min, and if current is max, voltage is min.
> If you look at this in a "sine wave mode", in one plane is a voltage sine wave and at 90º to this plane is another plane with a sine wave of current. This current sine wave is also 90º out of phase with the voltage sine wave.


I understood that when I wrote that post, I didn't think he was talking about that. I do understand sine waves. In the example you give it does seem as if voltage "moves", but it really doesn't and I'm not sure if Pete understood that. That's why I included the car analogy. In your example 0 voltage is valid. What I was talking about was it's relationship to inrush current. That is a one time event when starting a motor and letting it run continuously. Of course, in a refrigeration system, there is an inrush current every time the compressor kicks in. I'd still consider that a one time event as long as the motor is running.

Rich


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## veryoldschool (Dec 10, 2006)

rich584 said:


> What I was talking about was it's relationship to inrush current. That is a one time event when starting a motor and letting it run continuously. Of course, in a refrigeration system, there is an inrush current every time the compressor kicks in. I'd still consider that a one time event as long as the motor is running.
> 
> Rich


And getting back near the topic... :lol:
The refrigerator motor/compressor cycles, so "it has an event" each time it comes on.


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## Rich (Feb 22, 2007)

veryoldschool said:


> And getting back near the topic... :lol:
> The refrigerator motor/compressor cycles, so "it has an event" each time it comes on.


I do believe I said that...:lol:

Rich


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## P Smith (Jul 25, 2002)

Since the refrig using one phase source, chances to get not 0 voltage during the start is high, then inrush current would be much less. So, it's depend of time.


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## Rich (Feb 22, 2007)

P Smith said:


> Since the refrig using one phase source, chances to get not 0 voltage during the start is high, then inrush current would be much less. So, it's depend of time.


The inrush current on a motor is always constant on a bench. The load might cause it to vary, but with a constant load such as a compressor motor sees on a refrigeration unit, the inrush current should be pretty constant. But remember, it's so brief that it really makes no difference when you are looking a the total draw of the motor.

Rich


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## P Smith (Jul 25, 2002)

You forget the current is AC, 60 Hz.  V=110V*sin(t).


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## ThomasM (Jul 20, 2007)

veryoldschool said:


> Power supplies aren't quite the same as motors.


Especially the modern "switching" power supplies employed in most current electronic equipment (including DirecTV receivers).


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## ThomasM (Jul 20, 2007)

TDK1044 said:


> 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?


Well, if you like making the electric co. rich, no big deal at all.

I bet you would be shocked (no pun intended-well maybe a little  ) if you knew how much electricity all that stuff you have is using when you are NOT using it!!


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## JonW (Dec 21, 2006)

The bottom line is power efficiency could be improved greatly without any loss in functionality, but engineers have to actually design for it.


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## P Smith (Jul 25, 2002)

JonW said:


> The bottom line is power efficiency could be improved greatly without any loss in functionality, but engineers have to actually design for it.


Perhaps you missed - they did [HDD spin down at least] in year 2000 when PVR501 came out; but someone did make opposite decision for ViP models, seems from same 'pool of innovative ideas' where is DVR/receiver (Linux based) reboot once per day instead of find bugs what a cause of memory leaking.


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