how much standby power do ALL your appliances use?

"Phil in Melbourne"

Firstly, with say a 40 watt light bulb - should read 40 watts.

Then, with a 10uF mains capacitor - should read zero.

You must use gas for nearly everything.

Darn cold in Melbourne at the moment, ain't it?

I suppose you house is full of CFLs too ??

...... Phil

If you are dealing with mA current why not just make up a little rig so you can use a multimeter and get some accurate readings? For the high power stuff you can just walk out to your power box and see how long it takes to spin around.

The only thing crazy is your low bill! I would guess most people are at least 3 times that much. Though I remember a british study that said 10th of all home power is being used by standby, and it was enough for them to start banning devices from having a standby mode, effecitvely eliminating 'soft power' switches. They had some interesting circuits for TV's, because they want the remote control to actually phsyically switch a relay to turn power off completely. They used capacitors to store enough energy for the switch back on, and then there were arguments that that used more power than hours of

The best idea I saw was a power board that would switch the outlet off when the power draw was under a certain amount for a certain amount of time, like less than 5W for more than 1 hour. Then you had to physically switch the outlet back on again. Saw them years ago in a british magazine and never saw of the device again (it was like 150 pounds for a 4 outlet powerboard, which is probably why...)

There are some atrocious and very suspicious figures there! I would seriously doubt the low level accuracy of the meter. I believe this exact meter (rebadged I think) was recalled by one supplier for being inaccurate at low currents.

Dave.

There are some atrocious and very suspicious figures there! I would seriously doubt the low level accuracy of the meter. I believe this exact meter (rebadged I think) was recalled by one supplier for being inaccurate at low currents.

Dave.

The instrument you are using is not precise, and I would not consider it accurate. Watts are very difficult to measure directly because they are a result of a number of electrical factors from the combination of current, voltage, and the phase of the load. The simple power meter that you bought can only measure a pure resistive load, such as a light bulb, or a heating element that are not thyristor controlled. It cannot measure a fluorescent lamp because it would be driven through a current regulated reactive device called a ballast.

Most appliances including your TV, computer, and many home entertainment systems use switching power supplies. These are complex power supplies using high frequency inverters. Their load on the AC line cannot be easily directly measured. They change the phase of their power consumption depending on how they are loaded. Internally they use a system of changing the switching duty cycle for their inverter at a very high frequency, which really makes things more complicated.

In your list you actually have some items that are indicating 0W consumption, and I know for a fact that they do draw some power. The readings of the items below are make no sense at all. If you have a lit LED panel, there has to be some power being pulled from the AC mains. You would have to have perpetual power do have no power consumption! Your IR activated remote has its processor working all the time in order to know that the remote has been commanded. The phase of the loading of these devices is fooling your Watt meter.

New fridge with LED panel lit up, compressor not running 0W (Impossible) IR activated remote control curtains 0W (Impossible) Toaster with 7 segment standby indicator 0W (Impossible)

I suggest you take that gadget you bought, put it back in to its box, and send it back for a refund if you can!

There are power analysers that can make an accurate measurement, but this type of instrument is very expensive in relation to what you would spend for home use. These analysers can look at apparent, resistive, and reactive power. Then they can do some calculations to determine the actual power consumption.

What you can do is get a good quality true RMS DVM that can measure AC Amperes (expensive). You will then have to rig up a series adaptor to put the meter in series with the load. Now you can take a current measurement. From this you can then calculate an idea of the power consumption.

For most appliances that have a standby mode, disconnecting them from the power when not in use is not a good practice. You will find that over time you may end up with some power supply failure, and at least you will shorten their lifespan and dependability. As for TV sets, VCR's (if you still own one), and many other types of appliances, they have memory set-ups. If you leave them too long without power, their internal time keeping and set-ups will not be maintained.

The bottom line is that the numbers you came up with have no accurate meaning!

Hi Phil,

I have two of these meters. I spent quite a bit of time mucking about with them.

They are fine measuring power down to about 15-25 watts but are not accurate under that. They will definitely show a 7W light bulb as consuming zero power.

My power consumption is about 19KWHr per day. About half of that consumption is standy power for me. (I'm a "vampire power" King! :) )

I cut my Electricity bill by about $70/quarter by shutting down some of my installations which were constantly consuming standby power, since my circumstances had changed and it was no longer necessary to run these things constantly.

Gas pilot lights can consume a lot of gas too.

Ross

"JANA"

A typical SMPS is just another electronic load on the AC supply - but without the complication of a laminated iron transformer. This makes finding the power consumption easier.

Three facts are used:

1. Electronic loads draw the vast majority of their current ONLY during the peaks of the AC supply voltage, the voltage at this time is close to

1. When the supply voltage is a fixed value, the watts consumed is found by multiplying the average value of the current drawn by that fixed voltage. ( Same as you would find the power being drawn from a battery.)

2. Standard DMMs will read the average rectified value of an AC current - scaled up on the display by 1.11 to show the * rms value* of a sine wave.

So, putting this altogether:

All you do is find the AC current reading on a standard (ie non true rms) DMM and multiply that number by 325 then divide by 1.11. The result should be the correct power in watts, within 10%.

Remember - this is for loads that do NOT use an iron transformer, where the magnetising current draw is almost 90 degrees out of phase with the AC voltage.

Also, any SPMS that features electronic " power factor correction" ( PFC) draws current that is essentially in phase with the AC voltage and of sine wave shape. So any DMM ( or moving coil or moving iron meter ) will give the correct value for the load current and one just multiplies this by 240 to get the power in watts.

..... Phil

These figures are obviously wrong, just below the resolution of your cheap meter.

MrT.

Not while it costs you more for billing ("service charge") than for the electricity used on those devices anyway!

And before someone jumps in, generation plant, line costs (or wire size), transformer size, maintenance costs etc. are nearly ALL related to usage, NOT non-usage. Billing is about the only thing totally unrelated, yet costs a fortune IMO. And it's not just electricity billing that's a total rip off either. As with Bank charges, they charge whatever they can get away with, if you have no alternative.

MrT.

I made a simple Power Measuring device from a Silicon Chip Kit. Dick Smith used to sell them , Cat 7217 was the number. Only cost around $70 and it works really well. Accuracy is around 1% , (can be improved if you have a srandard load) and reads from 0.1 watts to 3750 watts. Its based on a special Analog Devices IC ADE7756AN. Doesnt get fooled by power factor or switchmode PS. Think Jaycar sell em too.

I can also vouch for the SC power meter design. Have found no problems so far, and is fairly accurate down to it's lowest resolution of 0.1W.

I got mine for something like $30 at the DSE kit fire sale :->

Dave.

IIRC, and I might be wrong, that meter will read up to 10A, or 2400W. To expect it to read less than 10W accurately would imply an accuracy of less than 0.5%, while [again, IIRC] it only claims to be accurate to

"Merlin Zener"

The problem IS we have almost no idea how the darn thing works.

Assuming it only has a single " Watts " range, with apparent resolution of

However:

The OP can easily calibrate his meter - or prove it a dud with simple tests, as I gave earlier.

If he connects a 56 kohm resistor as a load - it should read 1 watt.

Any value cap should read zero watts.

I betcha it don't.

..... Phil

But a $10 multimeter will do better than that by simply changing ranges.

MrT.

I expect it to be nearly as good as more reputable ones like the Kill-A-Watt available in the US market for under US$20. (quoted 0.2% basic accuracy for your interest) This one is *double* that price, so I'd say it's reasonable to expect similar performance.

Given that a very large percentage of ordinary people want (and expect) to use these devices for standby and other low power measurements (it's all the rage these days), then it's a very deceiving device indeed. That is why more reputable companies like the ATA online shop pulled it from the shelves, offered a refund, and sent an email and put ads in ReNew mag informing everyone that it was useless at low currents. From memory the figure quoted was 20W or so.

It's a heap of crap.

Dave.

You must be an American.

Pure TRIPE. No such ban exists. Get all your info from frothing-at-the-mouth journos do you ? There are however IEC guidelines for standy operation power consumption and they're hoping to get it down to ONE watt IIRC in new products.

When I measured my set-top-cable-box I did however notice that it measured 17W in active OR 'standy mode'. Now that's inexcusable (Samsung btw and supplied by the cable co so no choice in the matter).

Graham

And I nearly forgot to say, no 'hard' power switch either, so unplugging is the only way to stop the energy waste.

Graham

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The new TV came without a line switch. Couple of bucks and five minutes and good-by stand by.

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The MANUFACTURER should fit one. In this day and age such power hogs are INEXCUSABLE.

My 21" Super-res CRT SONY PC monitor only consumes 3W in standby for example. Why should TVs be worse ?

Graham