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Thread: Excessive Standby Power Consumption

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    Default Excessive Standby Power Consumption

    I live in QLD and have one of those wireless energy monitors and I bought one of those power meters from jaycar and was quite suprised at what some home appliances use just sitting there in standby doing nothing. It says the accuracy of the jaycar device is +/- 10watts or +/- 4%

    My Panasonic NN-ST677M microwave uses 71 watts doing nothing except for displaying the time wtf?? At 16.29 cents per kWh thats $100 a year down the drain, luckily the power point switch for the microwave is easy to get to.

    My Samsung LCD TV uses 24 watts in standby, again $34 a year. Considering most TV's specifiy less than 2 watts in standby that's excessively high.

    Washing machine 9 watts, etc etc.

    The microwave specs don't specify the standby usage for the microwave, is there any energy standards these appliance manufacturers have to stick to? If the tech specs don't match what the thing actually uses would this entitle the purchaser to a refund?



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    Wink Power consumption?

    Methinks you should cross check the accuracy of your readings. Perhaps it is set for 24 Hr readout.
    Try reading your Supply Power Meter overnight. Make sure your HWS is off.

    Kindest Regards, " The Druid ".......

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    The Jaycar power meter you plug in then you plug the device into the meter, press the function button a few times for watts and it shows you how many watts it is currently using or it can show you how many amps it is drawing and has nothing to do with the HWS or any other device for that matter.

    It reads 71 watts and when the door opens it goes up to 80 watts because of the light, then when the door closes it goes down to 71 again. 9 watts for the light sounds about right so I highly doubt it's what you suggested. Also the TV when off reads 24 watts when its on it reads about 280 watts depending on the brightness which is right (well the on usage is right but i think the standby should be lower).
    Last edited by ingxen; 14-05-09 at 01:31 PM.

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    Something is not right here:

    " * The interim target is a passive standby power consumption of less than 4 watts by 2007
    * The ultimate target is a passive standby power consumption of less than 1 watt by 2012

    This target applies to all microwave ovens brought into Australia for sale in that year. NAEEEC proposes to monitor the sale of microwave ovens in that year and to move toward regulation should that target not be met by a significant number of suppliers of products."


    That shows that microwave ovens should use a max. of 4 watts in standby.
    If your oven really is using 70W in standby, it must be warm to touch as that much power has to generate heat.

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    Interesting read mandc, the site says it is a "target" only and that no regulation will be put in place unless a significant number of suppliers meet the target.

    The three options I see is the microwave is designed that way, the microwave is faulty or the jaycar power meter is faulty but like i said it reads 280 watts when the TV is on and that's what my TV specs says the power consumption is meant to be when its on.

    The Jaycar power meter accuracy is +/- 10watts or +/- 4% in the instructions so the 71 watt reading could be 61 watts but even still.. wtf??

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    Wink

    Try the Jaycar with a known 60 W globe or similar.

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    Cheers I was going to try that tonight, I was having a chat to a couple of the guys at work and they said to try 25 watt bulb, 60 watts and 100 watts and see what I get as it might only be accurate past a certain wattage.

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    I also bought one of those units that Jaycar sells, but I got mine from Springers (solar shop), I am not happy with the unit, its hard to make sence of and the instructions are poorly written like converted chinese..

    My fridge reads 100 watts on the watt setting and 1.03 kwh on the kwh setting, with a standby reading of 63 watts.

    Then I tried the freezer and got 120 watts and 1.30 kwh and it has 0 watts standby

    Then my computer, 120 watts and 0.599 kwh with 65 watts standby.

    I programmed 0.15 for the cost scale and my computer supposedly used $22.50 power in 8 hours.

    I think the unit is junk or its cause of the poor manual. I was going to get one of those power box units installed from the government plan, hope that displays something I can make sence of.

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    Senior Member Studio1's Avatar
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    I wouldn't put too much faith in the accuracy of these el cheapo units.

    Yes, they would work and probably give you reasonable results, but that's about it.

    If you have a decent multimeter you can do your own power calculations. A clamp meter is just as good if not better = easier to insert in the power chain.

    With a multimeter, all you need to do is make up a plug / socket arrangement that splits the phase and provides two leads to plug into your meter. The neutral and earth go straight through from plug to socket.
    A split-phase tapon is the ultimate thing here but I don't think they make them any more.
    Anyway, set your meter to AC amps or milliamps and check the current. A few simple calculations will give you the instantaneous wattage.

    Oh, and 70 watts is too much for a microwave in standby. Something weird going on there.

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    Senior Member skozzy's Avatar
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    I retested the Microwave, this time I pushed the reset/memory clear button on the tester and left it at default settings, 0 watts standby, 30 wats with the door open, 1660 watt when running, supposed to be an 1100 watt microwave.

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    Quote Originally Posted by beer4life View Post

    Try reading your Supply Power Meter overnight. Make sure your HWS is off.
    Sorry I misread your post yesterday I thought you mean't the wireless supply meter that was installed, but yes I will try to use the meter box power meter during the day and I will switch all the other circuits and devices off.

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    Quote Originally Posted by skozzy View Post
    I am not happy with the unit, its hard to make sence of and the instructions are poorly written like converted chinese..

    My fridge reads 100 watts on the watt setting and 1.03 kwh on the kwh setting, with a standby reading of 63 watts.
    There is no kwh setting for point in time measuring im almost positive, the kwh setting is a total of how much the thing has used since the counters were cleared kind of like your power box meter so thats where you may have got confused.

    I have read of some units reporting way higher watts usuage but the also reported higher than normal voltage and amps and the watts is calculated from the voltage and amps. The unit apparently can be calibrated as there are two pots inside the thing.

    Quote Originally Posted by skozzy View Post
    I think the unit is junk or its cause of the poor manual. I was going to get one of those power box units installed from the government plan, hope that displays something I can make sence of.
    The power unit box from the government is at best a rough guide to how much power your using, it has a slow refresh time (upto 30 seconds) so it can make it tricky to find out exactly how much a particular device is using as something else might cut in. The government thing is the same as the clipsal centameter and the accuracy below 1A is not specified 1A - 3A better than 10% and 3A + better than 5% so the jaycar device is more accurate.
    Last edited by ingxen; 15-05-09 at 01:14 PM.

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    Quote Originally Posted by Studio1 View Post
    I wouldn't put too much faith in the accuracy of these el cheapo units.

    Yes, they would work and probably give you reasonable results, but that's about it.

    Something weird going on there.
    I didn't have a portable lamp that has a 240 volts so I used a desktop lamp with a transformer that has a 35w setting and 50 watt setting to confirm the thing is working correctly and at 35 watt it reported 34 watts and at 50 it reported between 49 and 52.

    I found a review of the thing on dansdata

    Cheap meters are also practically certain to fail to accurately record the power consumption of something that draws very short bursts of power to keep some standby circuit energised.

    But overall, these simple meters are tremendously useful. Every home really should have one.
    Maybe that's whats happening here, maybe the microwave has very short bursts of power to keep the standby going and the thing is getting confused and reports a much higher wattage reading?

    I think the thing is pretty accurate at higher wattages but at low wattages it can't cope.

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    Quote Originally Posted by ingxen View Post
    I didn't have a portable lamp that has a 240 volts so I used a desktop lamp with a transformer that has a 35w setting and 50 watt setting to confirm the thing is working correctly and at 35 watt it reported 34 watts and at 50 it reported between 49 and 52.

    I found a review of the thing on dansdata



    Maybe that's whats happening here, maybe the microwave has very short bursts of power to keep the standby going and the thing is getting confused and reports a much higher wattage reading?

    I think the thing is pretty accurate at higher wattages but at low wattages it can't cope.

    try plugging a crt monitor or tv into it and switch it on and let it go into standby and wait a few minutes. i would be interested to see the results.

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    Quote Originally Posted by skozzy View Post
    I retested the Microwave, this time I pushed the reset/memory clear button on the tester and left it at default settings, 0 watts standby, 30 wats with the door open, 1660 watt when running, supposed to be an 1100 watt microwave.
    Sounds about right. The value of 1100 watts you are referring to is the output power of the magnetron or what is commonly referred to as the "cooking power".
    Remember that no electrical device is 100% efficient.
    Output power is always less than input.
    In this case your microwave is about 66% efficient.

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    panasonic, lg and sharp use 25 watt bulbs, while the halogen lamps in the sharp microwave/convection units are 70 watts or so (and expensive to replace)
    no way should your pana draw that kind of standby power, something is wrong with the reading, nothing inside them draws pulsed power either that could trick the unit.
    i fix this stuff... cheers
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    I did some some more testing, I switched off every circuit breaker except for the microwave circuit and switched the microwave off, looked at the power box meter (spinning disc) and it wasn't moving. Switched the microwave on and both the jaycar unit and the wireless monitor I have read about 70 watts.

    I did another test where everything was off except a 50 watt lamp and I looked at the rate at which the spinning disc was spinning, if the microwave is pulling 70 watts then it should spin at a rate faster than the lamp.

    I then switched off the lamp and turned the microwave on and the meter was spinning much much slower than the 50 watt lamp. Therefore the jaycar meter and the wireless meters are highly inaccurate at low wattages unless I have two dodgy meters which is highely unlikely. They seem quite accurate though at higher wattages.

    I estimated the draw from the microwave to be under 4.5 watts could someone please check below to make sure I have calculated correctly. I did this by looking at the meter and it says 266.6 revolutions/Kilowatt hour. The meter has 100 marks on it all the way around. So 1000 watts = 1 kilowatt

    4.5 watts / 1000watts = 0.0045 percent

    0.0045 * 266.6 = 1.1997 revolutions per hour for 4.5 watts

    1.1997 / 60 minutes = 0.019995 revolutions per minute for 4.5 watts

    0.019995 * 100 = 1.9995 marks on the spinning disc.

    I timed for a minute and it was very close to 2 marks on the disc on the power box meter.

    There must be something like the Dansdata review I posted above that is causing the units to get confused because the accuracy of the jaycar device states +/- 10 watts or +/- 4% and it states the range from 0-3010 watts and less than 4.5 watts to the 70 watt reading is out by more than that. All the higher wattage tests I have done are pretty much spot on.
    Last edited by ingxen; 18-05-09 at 02:07 AM.

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