Some of this simplification is confusing :-).
Rather than muddying the waters further by commenting overall I'll make one
set of closely related statements re one thing yu asked about and which,
for practical purposes is all you need to know. Some of this has been
covered by others.

- Electrical energy is sold in "units" where one unit =3D 1 kW.hour

- The most useful measure to obtain in this case is the occurence of units
or "sub units" of energy.

- All domestic energy meters that I have seen

  -- Flash an LED every time a sub-unit or electrical energy has been
supplied.
  -- Have a marking that states how many times the LED flashes per kWh
            Call this FPU =3D flashes per unit

- Some meters I have seen used 1000 flashes / kWh
   Others 3600 flashes/ kWh

*To measure energy usage:*

Sum LED flashes
Divide sum by FPU =3D kWh supplied.


            Russell






On 21 May 2016 at 05:59, Justin Richards <justin.richards@gmail.com> wrote:

> I am sure I had this well understood once but it seems I need a revisit.
> However, the texts are ambiguous.  They refer to watts as the instantaneo=
us
> energy but I think it is energy per second.
>
> Assuming DC supply of 1 volt across and a purely resistive 1 ohm load i.e=
..
> 1A flowing thru it.
>
> Being technically pedantic are these statements correct:-
>
> 1. 1 watt =3D 1 joule per second
> 2. a rate of 1 watt is the POWER
> 3. energy is consumed at a rate of 1 watt
> 4. after 1 second the load has dissipated 1 watt.second.  The seconds
> cancel so (1 joule / sec) * sec =3D 1 joule
> 5. after 5 secs it has consumed 5 watt.seconds =3D 5 joules
> 6. after 1 hour it has consumed 1Wh which is equal to 3600 watts.seconds =
or
> 3.6 kJ?
>
> whereas these statements are incorrect:-
>
> 1. a rate of 1 watt is the POWER CONSUMPTION
> 2. energy is consumed at a rate of 1 watt per second.
> 3. after 1 second the load has dissipated 1 watt
> 4. after 5 secs it has consumed 5 watts
>
> I ask because I would like to build a device similiar to a hackaday proje=
ct
> called Internet-of-Things-Power-Meter which counts LED pulses produced by
> modern house power meters.
>
> On the hackaday project (and elsewhere) they state "Modern power meters
> have a LED blinking every time a Watt is used" I have yet to check but I
> think more correctly it flashes once every 1Wh. So I would like to conver=
t
> this to watt.seconds (the so called instantaneous power) , Wh and daily
> consumption.  I assume daily consumption could be stated in terms of Wd o=
r
> watt.day.
>
> Am I on track?
>
> Justin
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