Justin, It is easy to get confused, and I think that there is a better way to state= things. Energy is expressed in Joules when you talk about standard units, and power= is expressed in watts. 1 Watt being 1 Joule spent in one second. For AC power, the joule and the watt are too small, so the energy company u= se the kilowatt-hour. if you just read exactly what it is, it is the energy that a 1kW power sour= ce consume in one hour. So 1 watt-hour is 1 Joule per second spent during one hour or 3600 J. and a kilowatt-hour is 1000J per second spent in one hour or 3.6 x 10^6 J. 1 kW-h =3D 1000 w-h =3D 3,600,000 J =20 Nothing more complex than that. My $0.02 contribution, Jean-Paul N1JPL > On May 20, 2016, at 7:25 PM, Justin Richards = wrote: >=20 > Hi Brenton, >=20 > thanks for the confirmation. >=20 > Initially I thought I had it all sorted but then started to struggle whil= e > thinking about the math required for the conversions. >=20 > I think my biggest issue was I had accepted power as the instantaneous > value where it is actually the energy for a given second. >=20 > Ok I guess to refer to watts as the instantaneous value but not ideal whe= n > it is needed to be used for calculations. >=20 > Justin >=20 >=20 >=20 >=20 >=20 > On 21 May 2016 at 06:18, Brent Brown wrote: >=20 >> Hi Justin, >>=20 >> Yes, there certainly is a lot of mixed up language out there when it com= es >> to >> describing power and energy. But everything you say sounds correct to me= , >> well at >> least from a skim read ~ good work! >>=20 >> Here in NZ the domestic user buys, and sometimes sells, electricity in >> units of kWh. >> I believe the most common pulse output from a meter is 1000 pulses per k= Wh >> (=3D1 >> pulse per Wh). >>=20 >> And yes, the unit is effectively energy/time * time (where the divide an= d >> multiply by >> time cancel out) but it's relatively easy to understand and avoids >> introducing another >> term to the consumer, ie. Joules. Take for example a 1kW bar heater >> running for >> 1hour =3D 1kWh... most people can visualize/appreciate that, even though= a >> 1kW bar >> heater is not as ubiquitous as it used to be. >>=20 >> On 21 May 2016 at 1:59, Justin Richards wrote: >>=20 >>> 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 >> instantaneous >>> energy but I think it is energy per second. >>>=20 >>> Assuming DC supply of 1 volt across and a purely resistive 1 ohm load >> i.e. >>> 1A flowing thru it. >>>=20 >>> Being technically pedantic are these statements correct:- >>>=20 >>> 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.second= s >> or >>> 3.6 kJ? >>>=20 >>> whereas these statements are incorrect:- >>>=20 >>> 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 >>>=20 >>> I ask because I would like to build a device similiar to a hackaday >> project >>> called Internet-of-Things-Power-Meter which counts LED pulses produced = by >>> modern house power meters. >>>=20 >>> 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 >> convert >>> this to watt.seconds (the so called instantaneous power) , Wh and daily >>> consumption. I assume daily consumption could be stated in terms of Wd >> or >>> watt.day. >>>=20 >>> Am I on track? >>>=20 >>> Justin >>=20 >>=20 >>=20 >>=20 >> -- >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >>=20 > --=20 > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist Just my $0.02, Jean-Paul N1JPL --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .