I saw a thing in the guardian about wasted power from appliances on standby.
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It said that a phone charger left plugged in is still drawing a little power because it's a transformer. Obv the amount is tiny because the thing isn't getting hot even but I have 10 or 20 USB sockets around the house, ordinary twin plug wall sockets plus the usbs. Have they got transformers in them? they must have, bu they aren't very big or warm even. Are they wasting power and money day and night? If not, why not? Round the study here there are half a dozen transformers plugged in and some seem warm, some stone cold. Why is that?
phone, modem, printer, laptop, laptop, monitor, phone charger for instance.
I am somewhat sceptical about many of these "things left on standby" articles.
Yes a transformer connected to the mains will dissipate a small amount of power when connected - even if unloaded. However most modern kit does not use a transformer connected directly to the mains. Since they are switched mode PSUs. The transformer they do have is very much smaller (they run at much higher frequencies so have better efficiency than that used in a traditional "linear" PSU).
Many of the PSU control circuits will in effect shut the supply down when there is no load.
(there are regulations that cover most separate chargers etc stipulate a max consumption of 0.3W when unloaded)
Most modern TVs etc will have standby power well under 0.5W
Might add up to a watt when not doing anything... so perhaps 10 kWh/year.
Most things are SMPSUs these days - they have a transformer, but it's downstream of conversion electronics. The unit is mostly but not entirely switched off when there is no load.
This guy reviews USB power bricks:
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selected examples have standby powers of 0.2W, 0.05W, 0.2W, 0.4W, etc.
So that's mostly a non-issue. Any old inefficient transformer PSUs (have a heavy iron lump in them) will make their way gradually towards the bin as their equipment becomes EOL.
The main issue with 'standby' these days is not things taking power when they are turned off (because ecodesign regulations have rightly jumped on that) but being on and taking power when you think they aren't doing anything. Like network switches waiting for packets which never arrive because the PC attached is turned off, TV boxes with the screen off but still chatting to the internet, monitors that are powered up displaying 'no signal' but not properly shutting down, etc etc.
In general, a good rule of thumb is the hand test. If the casing of the unit is warm, or there's a fan blowing air out of it, there's a handful or more of watts being consumed. If it's cold, assuming it's not a big lump to spread out the heat like a desktop PC, it's a fairly good bet that the power is minimal.
Well you would, because heating loads can be dozens or hundreds of kWh per day. It is possible to live entirely by appliance heat (computers etc) but you'd certainly know about it. Standby power, even egregious amounts, is not enough to heat your house. So you'd still be turning the boiler on, it would just run for slightly less time to compensate for the standby power.
(and standby power would make it hotter in the summer, when the heat isn't 'free' it's something you don't want)
It can measure the consumption of individual electrical loads, such as wall adapters.
To keep my VOIP phone running, is something like 17W for the networking equipment.
My two computers, in S3 sleep, one draws 5W, the other draws 7.5W (eight sticks of RAM). In soft Off (S5), the consumption is still
1.4W to 1.8W or so. I don't do anything about this, except to note it. If the LED backlight is left ON, on my keyboard, that pushes up the power another watt or so.
The individual SMPS adapters don't have zero consumption, but you can check them anyway, because some will waste a different amount than others.
The meter can measure real and reactive power, and whether you care about reactive, depends on the billing scheme.
Modern computer ATX power supplies are power-factor-corrected. This means the load presented to mains looks "almost resistive" with little reactive component.
For a while, LED lightbulbs made attempts at power factor correction, but the ones this year are pretty poor, measuring 0.6 or 0.7 . Only in a commercial establishment, with thousands of LED bulbs, would anyone be worried about "wires melting without breaker trip".
But anyway, these are the things that a Kill-O-Watt meter with localized outlet plug format, will address. If you're concerned about electric power billing for some reason, you can measure all sorts of stuff. Just take care with kettles. While the meter can be rated for 13A or 15A, some designs in the past got so hot inside, the solder on the shunt inside melted and the shunt shifted out of place. If you insist on doing a kettle, do it just the one time, do it for 30 seconds or less. And check the device in Google, for any stories of this sort.
Electric resistive items draw more than the rated power at start. And as the element becomes hot, the power will approach the nameplate value. The heater I bought, on the
750W setting, might have drawn 800W or 850W at startup, and depending on how overloaded a circuit is, just a set of resistive devices all coming on after a power failure, can trip a breaker. If the resistive loads were started one at a time individually, you could "sneak up" on the limit.
On the other side of the plastic casing, is the male counterpart that plugs into the wall. Using a short extension cord with your meter, you can lift it to a convenient place for taking readings. Mine is clamped to the table across the way at the moment (it's just a kind of yoke it rests in). I monitor PC power, to detect things like coin miners or the like (abnormal consumption seen as a function of the application being used).
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One other reason I own one of those, is when running pumps or thermal devices out of doors, I want to know whether the device is "nominal" or is "out-of-bounds", and my meter is good for that. Take a reading for 30 seconds, if all is well, unplug, take the meter back in the house and plug the load back in. It's just a quick check that something hasn't broken since last year.
If powered up they use an absolutely tiny amount of current, but some disconnect when you unplug the USB lead anyway. They don't use a transformer, they use a switch mode PSU, which are much more efficient. If you have any sort of mains power monitor, or smart meter - try truning everything off but the sockets, so you can see what they use.
In the old days they had iron core transformers in and ran warm to the touch. Modem PSUs of old were of this sort and early mobile phones.
They have been switched mode 90+% efficiency for a very long time. It is possible some wall based ones will power down if not on load but I expect they do run 24/7 and consume a small fraction of a watt each.
A rough heuristic is that if a PSU is heavy then it will waste power.
Those that are warm are likely to be iron core transformers or running a relatively high power load. The rest will be switched mode PSUs.
Most of them will use a small amount of power each in standby but it should be >0.5W and more likely around 0.1W. My mains monitor socket doesn't go low enough to measure the ones I have to hand.
Things to really watch out for are some older TVs which by default run their digital tuner continuously by default (~25W). It is worth investigating your base load and lowering it if you can in the present climate with electricity prices about to go through the roof.
my old nokia 1100 has a transformer in the charger and puts out less noise than those bloody switched mode ones with no transformer that draw next to nothing when not being used...
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