Energy meters pros and cons.

[ericmark]

I have three not including clamp on ammeters, one is clipped onto incoming supply and covers whole house, the other two plug in, one of the plug in meters is self contained you plug it in and return latter to see max, min, total, and time under test. The more expensive meter does less,

looks very pretty, but really does not tell you much, the rest are similar

If it actually said average last 24 hours it would be more use, but until just before midnight it really tells one very little, to simple meter gives power factor, and watts per hour watts per day how does that help, it was by the way my kettle.

OK it is a toy, but did expect the computer linked one to be better not worse than stand alone. Are they all this bad? The kettle boils a cup at a time so every time one presses the button should use same amount of power, so different height one cup, two cups or three cups hang on not two spikes the same?

And power usage (W) where is the watt/hour or kilowatt/hour should in not be monitoring energy not power?

 

[winston1]

The clip on ones are rubbish and do not do as described. They measure current only, and assume voltage, and obviously cannot take account of power factor.

 

[JohnW2]

The clip on ones are rubbish and do not do as described. They measure current only, and assume voltage, and obviously cannot take account of power factor.

I can't remember when/where, but I've seen clip-on ones that also have a mains feed (hence know about voltage and PF) - the advantage obviously being that one can undertake 'whole installation' monitoring without have to think of a way of breaking into the meter tails/CU feed for the current measurement!

However, for what they are really intended for (primarily a rough indication of appreciable changes over time) the 'domestic clip-on only' ones are probably adequate for that purpose.

Kind Regards, John

 

[ericmark]

I don't think I have ever found a use for the whole house meter, well maybe working out when my wife has put the kettle on so I can join her for coffee, even that does not help save energy as kettle boils a cup at a time.

The simple plug in one was a help testing fridge/freezer it did pick up when the thermostat failed stuck on, however items like washing machine and dish washer no real help as so many cycles and it also weighs cloths so can't really work out what they use or if any real way to save. I wanted a remote switch and thought I would get combined switch and monitor so I could see how much power other items other than freezer were using where it was not a simple read the label job as load and time varied. I expected a proper graph however the graphs shown are really useless.

This graph from this morning shows when the outside light came on, at 10W.

If you compare that with one shown night before for kettle

it seems a 10W outside light uses as much energy as a one cup kettle! Hovering the mouse pointer over the graph shows it lit at 7:49 and says 2 which I assumes means it used 2 watt hour? The last two peaks are still shown for the kettle with average hour use and show 40 and 75 so it would seem I made one cup with 40 watt/hour and two cups with 75 watt/hour, but no instructions I am guessing the little window is that peaks usage?

the picture I think shows what I used making 2 cups of coffee, however on the web site there are question and answer

Q: What information is available from the adapter?
Answer: The monitor will transmit the following data every 10 seconds over its OpenThings interface:
- Active(real) power, P, (Watts)
- Reactive power, Q, (VAr)
- Voltage, V (Volts)
- Frequency (Hertz)
From this information the apparent power S (VA) and hence the Power Factor cos φ etc. can be calculated.

Well can't find the frequency or voltage and there does not seem to be anything to show if figures are P or Q. The User guide reminds me of a chocolate fire guard. It really does not tell you how to use the device.