Measuring The Wattage Of Equipment

[rameez]

Hi All,

I just want to know is there any equipment that can be used to measure the wattage of a electrical or electronic device real time when it is used. I mean is this a costly affair?.

Can anyone tell me.........say for example do laptops really consume low current than the desktop and does a color TV consume more than black and white....what i am trying to find is does the amount really becomes high...in day to day use......

i know that volts * current is equal to watts but to my knowledge it is not that simple to calculate as in theory.....any electronic engineers in AL can help out

[Sifaan]

Hi All,

I just want to know is there any equipment that can be used to measure the wattage of a electrical or electronic device real time when it is used. I mean is this a costly affair?.

Can anyone tell me.........say for example do laptops really consume low current than the desktop and does a color TV consume more than black and white....what i am trying to find is does the amount really becomes high...in day to day use......

i know that volts * current is equal to watts but to my knowledge it is not that simple to calculate as in theory.....any electronic engineers in AL can help out

you already have a device paid for and installed by CEB/LECO

If you can switch off all other appliances in the house, then you can run the appliance for a particular period and see what the consumption is. You can also do it without switching everything off, but then the calculation is a bit more complex.

for things like a TV it's fairly constant usage, but more tricky with fridge, A/C etc as the power consumption varies based on whether the compressor is running or not, etc.

[MrCat]

Hi All,

I just want to know is there any equipment that can be used to measure the wattage of a electrical or electronic device real time when it is used. I mean is this a costly affair?.

Can anyone tell me.........say for example do laptops really consume low current than the desktop and does a color TV consume more than black and white....what i am trying to find is does the amount really becomes high...in day to day use......

i know that volts * current is equal to watts but to my knowledge it is not that simple to calculate as in theory.....any electronic engineers in AL can help out

There are Wattage and Current meters available for sale. Try searching on ebay. Never used one personally, I was thinking of getting one just for the heck of it.

[hyacc]

Hi All,

I just want to know is there any equipment that can be used to measure the wattage of a electrical or electronic device real time when it is used. I mean is this a costly affair?.

Can anyone tell me.........say for example do laptops really consume low current than the desktop and does a color TV consume more than black and white....what i am trying to find is does the amount really becomes high...in day to day use......

i know that volts * current is equal to watts but to my knowledge it is not that simple to calculate as in theory.....any electronic engineers in AL can help out

Not sure whether it's available in local stores. I bought this type of one off ebay and it works well.

http://cgi.ebay.com/Energy-Evaluation-Monitor-Power-Saving-Meter-AC-Outlet-/310325969838?pt=LH_DefaultDomain_0&hash=item4840de83ae

[mnaka]

You could use an ampere meter and multiply the value from voltage

[SeanD]

any electronic engineers in AL can help out

Yes we can, by saying that there is no point focussing on a "wattage" of an item, cos it doesn't really exist. Wattage is really just a thermal measure, a measure of how much heat that item is putting out. Think of keeping your hand on a 100 watt lightbulb...you will get my point. Look at it this way, when you see wall sockets, they are rated 5 amps, 13 amps, 15 amps etc. That is because they are designed to be used with a certain load current, nobody cares about how many watts you're drawing out of a plug point but how many amps your appliance is rated for (usually most appliances have an Amp rating as well). Your trip switches are not rated to break at a certain wattage but exceeding a certain current.

In any case, the wattage of any item is almost never constant, because it depends on how much of a load is on that appliance. For example, your monitor will have a different "wattage" (read: thermal output) based on what sort of image is being displayed on the screen (yes, depending on the colours), your speakers a different amount based on what is being played through them, together with other factors like resistance in the device, in the cables, etc. etc. What you're seeing displayed there is actually just an average over certain test scenarios (this is less likely to fluctuate for current consumption).

And then it doesn't end there, cos it also depends on the efficiency of the actual appliance (eg: a colour TV may consume more than a black and white, but if the design of todays LCD is much more efficient than the 30 year old B&W, chances are it actually consumes less than the old box)...not much worth worrying about cos the differences will have minimal effect on your actual light bill.

Bottom line, don't waste time chasing some figure like wattage, because that's a bit like chasing after the unicorn. If you really really want to measure wattage through a device then you can get some expensive lab equipment (expect to spend upwards of 2 lakhs)...but for your intents there is absolutely no point. Anything that claims to be a watt meter off the shelf probably isn't very reliable at all.

Rather, borrow a reliable multimeter (not cheap off the pavement stuff, most anything you will buy for less than 10k is not very accurate ) like a Fluke 80 (these are not cheap, but certain friends of yours may have one if they're into electronics repairs) and measure the current consumption by using the ammeter function...you already know the Voltage (roughly) which varies between 220 to as much as 240 in SL at 50Hz...you can use the formulas you learned from your O/L science class even to calculate rough power (wattage)

Hope that is of some use. Suggest you do what Sifaan suggested, as I am not sure you want to be poking around with live current.

[Sylvi]

You could use an ampere meter and multiply the value from voltage

'mnaka',

You are correct.

Sylvi wijesinghe.

[jdnet]

Yes we can, by saying that there is no point focussing on a "wattage" of an item, cos it doesn't really exist. Wattage is really just a thermal measure, a measure of how much heat that item is putting out. Think of keeping your hand on a 100 watt lightbulb...you will get my point. Look at it this way, when you see wall sockets, they are rated 5 amps, 13 amps, 15 amps etc. That is because they are designed to be used with a certain load current, nobody cares about how many watts you're drawing out of a plug point but how many amps your appliance is rated for (usually most appliances have an Amp rating as well). Your trip switches are not rated to break at a certain wattage but exceeding a certain current.

In any case, the wattage of any item is almost never constant, because it depends on how much of a load is on that appliance. For example, your monitor will have a different "wattage" (read: thermal output) based on what sort of image is being displayed on the screen (yes, depending on the colours), your speakers a different amount based on what is being played through them, together with other factors like resistance in the device, in the cables, etc. etc. What you're seeing displayed there is actually just an average over certain test scenarios (this is less likely to fluctuate for current consumption).

And then it doesn't end there, cos it also depends on the efficiency of the actual appliance (eg: a colour TV may consume more than a black and white, but if the design of todays LCD is much more efficient than the 30 year old B&W, chances are it actually consumes less than the old box)...not much worth worrying about cos the differences will have minimal effect on your actual light bill.

Bottom line, don't waste time chasing some figure like wattage, because that's a bit like chasing after the unicorn. If you really really want to measure wattage through a device then you can get some expensive lab equipment (expect to spend upwards of 2 lakhs)...but for your intents there is absolutely no point. Anything that claims to be a watt meter off the shelf probably isn't very reliable at all.

Rather, borrow a reliable multimeter (not cheap off the pavement stuff, most anything you will buy for less than 10k is not very accurate ) like a Fluke 80 (these are not cheap, but certain friends of yours may have one if they're into electronics repairs) and measure the current consumption by using the ammeter function...you already know the Voltage (roughly) which varies between 220 to as much as 240 in SL at 50Hz...you can use the formulas you learned from your O/L science class even to calculate rough power (wattage)

Hope that is of some use. Suggest you do what Sifaan suggested, as I am not sure you want to be poking around with live current.

5 star post hoss!

[hyacc]

I think what he's looking for is a simple device to get an idea of power usage of home appliances and electronics and it's better to use a device like "kill a watt" without poking around with live current with multimeters or amp meters.

BTW I found out DialogTV decoder's power usage in "stand by" mode is as high as 12 watts while in operation it's 15 watts.

Edited June 23, 2011 by hyacc

[Sylvi]

I think what he's looking for is a simple device to get an idea of power usage of home appliances and electronics and it's better to use a device like "kill a watt" without poking around with live current with multimeters or amp meters.

BTW I found out DialogTV decoder's power usage in "stand by" mode is as high as 12 watts while in operation it's 15 watts.

'hyacc',

Clip On AC Digital Meters are available to measure Amperage cost of one Chinese made is under Rupees 2000.00.

Sylvi Wijesinghe.

[Sifaan]

on AC, measuring current and multiplying by voltage (=apparent power) is not necessarily correct (=real power), because the current and voltage waveforms may be out of phase.

if the purpose of this exercise is related to the electricity bill, you need to find real power, because domestic users are not penalized for reactive power.

[miniace]

BTW I found out DialogTV decoder's power usage in "stand by" mode is as high as 12 watts while in operation it's 15 watts.

Really..its like having a 60W equal CFL bulb switched on all the time ne

MINIACE