Do electric meter show KW rating that house uses at instantenous.

[kwired]

With 1/4 cycle sampling (or more) there is no need for any degree of time averaging. It simply samples, gives that value or instantaneous kW.
most meters aren’t configured that way from the manufacturer unless it’s requested.

For some of the GE meters, I can go in with MeterMate software and configure the LCD screen to show the instantaneous kW when the screen comes up. Is it exact for the time the screen comes up? No. BUT any analog or any other meter can’t do that either because the time it takes our brain to register what we are looking at the instantaneous kW has changed. For an analog meter that shows changing values isn’t exact either, but it’s close enough.

For the GE I-210+c, from the specifications for the meter chip:
“The meter chip has a 22-bit delta-sigma ADC with an effective sampling rate of 2520 samples per second.”

I would think refresh rates of the display can be a somewhat major factor in accuracy of instantaneous values displayed. I would also guess cumulative registers however will have higher accuracy with stored information.

 

[Carultch]

If a meter truly measured instantaneous power, then even for the most steady load possible, you'd get a different read-out depending on where the waveform is in its cycle, at the time your meter samples. Measure at the peak or trough of the waveform, and get the maximum power that is theoretically twice the average power. Measure at the zero crossing, and get zero. It would either have to time-average, or sample at specific points within the cycle and extrapolate through the assumption that it is a sine wave.

Whether it does this by time-averaging, or whether it does this by extrapolating the waveform, it still most likely would give you a cycle average power rather than a truly instantaneous power. The cycle average power is the more useful information to most users.

 

[kwired]

If a meter truly measured instantaneous power, then even for the most steady load possible, you'd get a different read-out depending on where the waveform is in its cycle, at the time your meter samples. Measure at the peak or trough of the waveform, and get the maximum power that is theoretically twice the average power. Measure at the zero crossing, and get zero. It would either have to time-average, or sample at specific points within the cycle and extrapolate through the assumption that it is a sine wave.

Whether it does this by time-averaging, or whether it does this by extrapolating the waveform, it still most likely would give you a cycle average power rather than a truly instantaneous power. The cycle average power is the more useful information to most users.

unless you are measuring DC source I think you kind of have to presume it will be RMS based as a general rule.

The steadier the actual load the more accurate readings will be? resistive loads will likely be pretty stable, high speed switching loads is where distortion can be a big factor in actual vs display values I would think

 

[Hv&Lv]

If a meter truly measured instantaneous power, then even for the most steady load possible, you'd get a different read-out depending on where the waveform is in its cycle, at the time your meter samples. Measure at the peak or trough of the waveform, and get the maximum power that is theoretically twice the average power. Measure at the zero crossing, and get zero. It would either have to time-average, or sample at specific points within the cycle and extrapolate through the assumption that it is a sine wave.

Whether it does this by time-averaging, or whether it does this by extrapolating the waveform, it still most likely would give you a cycle average power rather than a truly instantaneous power. The cycle average power is the more useful information to most users.

True..
Now I see the line of thinking.

For some reason I keep thinking demand intervals with 15 minutes intervals…
But yes. Sample at the zero crossing and get 0 instaneous kW.
I see now where your taking about time averaging intervals..

 

[wwhitney]

If a meter truly measured instantaneous power, then even for the most steady load possible, you'd get a different read-out depending on where the waveform is in its cycle, at the time your meter samples.

For single phase. For 3 phase and a linear load, it's constant, I believe?

Cheers, Wayne

 

[Besoeker3]

If a meter truly measured instantaneous power, then even for the most steady load possible, you'd get a different read-out depending on where the waveform is in its cycle, at the time your meter samples. Measure at the peak or trough of the waveform, and get the maximum power that is theoretically twice the average power. Measure at the zero crossing, and get zero. It would either have to time-average, or sample at specific points within the cycle and extrapolate through the assumption that it is a sine wave.

You'd want an oscilloscope for that. And you wouldn't need it to be a sine wave.

 

[jaggedben]

Ok, fer cryin' out loud, strike 'instantaneous' from the record and replace with something like 'contemporaneous'. At this point we are no longer answering the OPs question. To which the answer is most likely 'Yes' for any practical purpose.

 

[Besoeker3]

Ok, fer cryin' out loud, strike 'instantaneous' from the record and replace with something like 'contemporaneous'. At this point we are no longer answering the OPs question. To which the answer is most likely 'Yes' for any practical purpose.

Oh, it's just fun!!

 

[Hv&Lv]

Ok, fer cryin' out loud, strike 'instantaneous' from the record and replace with something like 'contemporaneous'. At this point we are no longer answering the OPs question. To which the answer is most likely 'Yes' for any practical purpose.

If we weren’t splittin’ hairs here what would we have to post all day??