Kill A Watt P4400 on sale
in [Repair]
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From: Dave Plowman (News) on 5 Sep 2009 14:16 In article <h7u9lj$8i7$1(a)news.eternal-september.org>, William Sommerwerck <grizzledgeezer(a)comcast.net> wrote: > > Those can be fine, accuracy-wise. But of very limited use. After > > all, it's not difficult to work out what most appliances cost to run. > When I get around to it, I'm going to put it on my fridge for a few > days. I want to see exactly how many kWh it draws over a week or so. You > can't do that with a clip-on, because refrigerators run intermittently. That's true - but what action will you take? You can hardly switch it off to save energy. Unlike heating and aircon. If it's old a new one will almost certainly be more efficient. But may cost more than it saves. -- *It sounds like English, but I can't understand a word you're saying. Dave Plowman dave(a)davenoise.co.uk London SW To e-mail, change noise into sound.
From: whit3rd on 5 Sep 2009 14:41 On Sep 5, 11:00 am, "Dave Plowman (News)" <d...(a)davenoise.co.uk> wrote: > Ah - right. Those can be fine, accuracy wise. But of very limited use. > After all it's not difficult to work out what most appliances cost to run.. Don't think small! I've used power meters to do LOTS of tuning operations. Consider an AB power stage, where 50W peak is available; you might allow 2W of quiescent power dissipation, and that means (under no-load conditions) cranking the final stage bias fully down, powering up the unit, and watching the power meter while slowly tweaking up the bias pot. When it gets to x + 2W, you're done. RF output power is awkward to measure, too; tuning a power oscillator with a power meter on the AC input is ... luxurious. Look, ma! No more RF burns! And that little kill-a-watt is a much nicer way to find out what the (duty-cycle-according-to-humidistat) dehumidifier really costs to run down in the basement, than an A/B comparison on 2006 and 2007 electric utility bills. I did the electric bill comparison first. Wish it was the other way around.
From: PeterD on 5 Sep 2009 14:44 On Sat, 05 Sep 2009 19:16:23 +0100, "Dave Plowman (News)" <dave(a)davenoise.co.uk> wrote: >In article <h7u9lj$8i7$1(a)news.eternal-september.org>, > William Sommerwerck <grizzledgeezer(a)comcast.net> wrote: >> > Those can be fine, accuracy-wise. But of very limited use. After >> > all, it's not difficult to work out what most appliances cost to run. > >> When I get around to it, I'm going to put it on my fridge for a few >> days. I want to see exactly how many kWh it draws over a week or so. You >> can't do that with a clip-on, because refrigerators run intermittently. > >That's true - but what action will you take? You can hardly switch it off >to save energy. Unlike heating and aircon. If it's old a new one will >almost certainly be more efficient. But may cost more than it saves. My sister replaced her old (died) fridge this spring. The old was not that old, about 6 years, IIRC. The new was a model considered energy efficient. She did notice a drop in electrical consumption with the new one, and figured that the new one would have paid for itself in about 4 to 6 years.
From: Jeff Liebermann on 5 Sep 2009 14:50 On Sat, 05 Sep 2009 13:11:29 -0400, "Michael A. Terrell" <mike.terrell(a)earthlink.net> wrote: > It is an inline device: ><http://www.p3international.com/products/special/P4400/P4400-CE.html> Some more... Photo of the insides of the original and the later P4440 versions. The P4440 is at the bottom: <http://802.11junk.com/jeffl/pics/drivel/slides/kill-a-watt.html> The original version has no memory (loses history if unplugged) and has only 4 buttons on the front. The later version has 5 buttons and retains usage history until the cap discharges. I don't have a P4460 (EZ) inside photo. I have about 4 of them, some of which are permanently installed monitoring the power consumption of various devices. I use 3 more for distributing the electric power bill on a mountaintop radio site (with poor weather protection). The main advantage is the low price. However, the operation of the 5 buttons is not very obvious and I have to keep a copy of the instructions nearby. Costco has the P4460 for $27. Recently, I've been considering alternatives, which seem to have some advantages, like less button pushing. I have one of these on order: <http://www.amazon.com/Energy-Meter-LCD-Display-EM100/dp/B000RKVK52> Black and Decker also makes one, but it's overpriced at about $100.: <http://www.blackanddecker.com/Energy/products.aspx> As for accuracy, the P4400 models that I have seem fairly accurate, even at low levels. I don't have an easy way to calibrate these, especially with odd power factors. My mechanical disc power meter and the numbers from a P4400 were quite close when I tested both in series running only a refridgerator for a month. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
From: Jeff Liebermann on 5 Sep 2009 15:03
On Sat, 05 Sep 2009 10:25:47 -0400, "Michael A. Terrell" <mike.terrell(a)earthlink.net> wrote: > A clamp on ammeter is fine for some uses. It doesn't log power >consumption. It is a tool intended for electricians, and most do not >give accurate readings on anything other than a pure resistive load. >Reading the actual load of a switch mode power supply requires a good >RMS converter in the meter. The same as the ones mate for the new >electronic watt hour meters. Its a poor worker who doesn't understand >his tools, yet defends bad work. I use both clamp-on and inline meters. The clamp-on is best for troubleshooting while the inline is best for monitoring. My no-name Chinese clamp-on meter does accumulate usage (logging), but does not have the power factor correction I need for dealing with inductive loads (motors), or badly designed switchers. The inline can also do cost calculations, which is something my customers can see and understand. However, the big advantage is that I can buy the inline meter for about $27, do my song and dance for the customer, and then sell it to him for about twice that. It also give the customer the impression that I'm tryting to save him money by monitoring his electricity usage. It's design makes it acceptable for leaving it in place for monitoring, while a clamp-on meter plus inline cord splitter, would be an ugly mess. Note: I'm not an electrician. This week, I fix computahs. Computer owners often want to know how much power their PC or monitor is burning. Hmmm... I just bought myself a new desktop and forgot to measure it. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |