Ever wonder how much running that PC all the time is costing you? How about that window air conditioner in the summer. Is my refrigerator running efficiently? The Watts up? power analyzer measures the power consumed by just about any device that you can plug into it. It can keep a running log measuring power in watts, line voltage and current and power factor. If you tell it what your electric rates are, it will tell you how much that device is costing you. A free software package available at the website puts this data in graphical form. If you purchase the upgraded software you can do long term real-time logging with one data point per second speed, instead of being limited to the 1000 data points in the Watts up? memory.
Let's try some (un)common household items and see how much power they use. Here's a standard 32" flatscreen CRT TV. (Just click on the graphs that follow to see a larger version)
Nothing out the ordinary here, fairly constant at about 90-100 watts. One of the features of the Watts up, is even though the best logging rate you can get is once per second, it actually measures much faster than that and will store instantaneous maximums. So let's turn on the max watts trace on the graph.
Yikes! The spike in the beginning is so large, the scale of the graph has been changed. Why the spike? I have a feeling in a couple of years, when most every set will be either plasma, LCD or DLP, people won't remember the "thump" their TV made when it was turned on. A coil of wire is wound around the CRT inside the set, which is energized momentarily when the set is turned on, to demagnetize the CRT. Your CRT computer monitor's "degauss" function is the same thing. One problem with this particular model set is that this degaussing circuit was not well designed, and eventually it would fail and the set's fuse would blow. We're talking a surge in the range of 10 Amps here, and the set's fuse is only 6 Amps. Mine's already blown once, but we don't use the set any more.
Here's a chart for our replacement 32" LCD set.
The set was only running for a few minutes so you see the vertical bar. Notice the power draw is constant around 115 watts. The power consumption of a CRT based set will vary as you saw in the above chart as it draws more power for brighter scenes, where an LCD set has a backlight that has a constant brightness.
Let's try some household appliances. How about a coffee maker.
This is a Cuisinart Grind-n-Brew, where it grinds the coffee beans for you then brews the pot. In the beginning you can see the short time where it's grinding the coffee, drawing about 100 watts. Then you see much more power consumption as the heater turns on to brew the coffee. When the coffee is done, the heater is only turned on once in a while to keep the pot warm.
Here's a typical front-loading washing machine.
Front-loading washing machines are very energy efficient, not only because they use very little water, but instead of the motor constantly turning an agitator, the drum only rocks back and forth. You can see each individual spike during the wash and rinse cycles where the drum rotates in one direction, stops, then rotates in the other direction. Where the spikes are not as pronounced you can see where the water is being pumped from the washer. At 12:35 on the graph you see the point in the rinse cycle where the drum is continually spinning. At 12:45 the washer is in the spin cycle and you can see the power draw increase as the spin speed increases. The largest spike is a very high speed spin that only lasts a few seconds, then at the very end you get a gentle rocking motion to free the clothes from the side of the drum. Since the Watts up knows how much my electricity costs, lets see the graph.
From this I can tell that it cost just about a penny's worth of electricity to do that load. Unfortunately, I don't have access to an older type washer to do a comparison, but I can assure you it would be using much more power.
Let's go back to the fun & games and measure an XBox360.
I expanded the vertical "power" scale of the graph a bit here. For the first 4 hours, I was playing "Test Drive Unlimited" so you can see the power vary as processing needs vary. For the next 4 hours, I downloaded a game demo through XBox Live and from then on the XBox was idling. So it was drawing 135 watts even when doing "nothing". How much did that cost me?
Hmmm About 5 cents to play the game, another 4 cents to download the demo and a bit more than 5 cents of wasted power. Maybe Microsoft could add a patch that shuts the unit down when a download is finished?
Now we go back in time, to when radios had little glowing glass bottles in them and you had to wait for them to "warm up". This is a Philco 8 tube 9-band shortwave table set from 1953.
Notice that over about 3 hours the power consumption rises from 75 to 95 watts. The first thing to consider is that it takes 25 watts just to run the heaters of those 8 tubes. I guess that 25 watts of heat comes in handy in the winter. These radios certainly weren't designed to "Energy Star" standards.
I'm not really sure yet why this is happening. Possibly as the radio warms up something is drifting off and causing the extra power drain. For all I know this could be normal. First thing would be to run the set with the back off and see if it still drifts. In any event, if I were to use this set daily, I'd do a restoration (replace all capacitors and check everything else) before I trust to leave it unattended.
I'll have more graphs from other appliances in future posts.
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