If I was doing it I would hire the data logger. Remember you will need the calibration certificate.if I were doing this, I would buy a Shelly EM
HmmIf I was doing it I would hire the data logger. Remember you will need the calibration certificate.
Actually 3,600 seconds in an hour (that was presumably a typo on your part). More importantly, not "watt/hour" but, rather watt.hour (i.e. watts x hours)So a watt is a joule per second, and the joule is a very small unit, so since 360 seconds in an hour, the are 360 joules in a watt/hour.
As above, the meter measures kilowatt.hours (kWh), not kW/h.So we use kW/h with the electric meter but kW with the clamp on (after some maths) so they don't measure the same thing.
Coupled with the above, that seems unnecessarily confusing. As you are aware, it's really very simple ...May seem odd but there is no time in a kW/h (the two times cancel each other) but there is time in a kW.
... you could not use that to show errors with an electric meter, it would need to be a calibrated data logger.
But to check the accuracy of the electric meter, as mentioned above, you need a calibrated data logger. ... There are many devices on the market, if I were doing this, I would buy a Shelly EM. ...
I don't think that 'calibrated' (or 'calibration certificate') are really relevant. If one wants to check the accuracy of a supplier's meter, all one really needs is a device which one is fairly confident will gives reasonably accurate readings.If I was doing it I would hire the data logger. Remember you will need the calibration certificate.
[ with 1 kWh being equal to 3,600,000 Joules ]
I would think that " kW/h " would be a useless, and essentially meaningless, measure of anything. If you had, say, a 2 kW load running for 50 hours, that would equate to 40 kW/h - but, as far as I can see, that information would be of little use to man or beast!
It would - but eric was not talking about kWh/h - he was talking (writing) about kW/h.Struggling with the last sentence. Wouldn't 100kWh in 50hours be equivalent to 2kWh/h?
I see your point, if the meter has stopped, and you plug in a 3 kW heater for 20 minutes and it shows 1 kW.h then not far out.If one wants to check the accuracy of a supplier's meter, all one really needs is a device which one is fairly confident will gives reasonably accurate readings.
I'm not sure what you mean by "the meter has stopped". If you mean that it has 'stopped working' (recording new usage) then one presumbly would not need to make any measurements to confirm that there was a problem!I see your point, if the meter has stopped, and you plug in a 3 kW heater for 20 minutes and it shows 1 kW.h then not far out.
One could use some sort of cheapo plug-in monitor to confirm that the heater was actually using 3 kW. However, as you say, that would only be useful if one could switch off all other loads.As to using a clamp on to see it really is 3 kW that's icing on the cake. But you need to be able to switch off all loads.
Don't forget that MCBs are current-operated. Even if each of the lamps were only drawing, say, 58W, it could have been appreciably more than 58 VA, hence potentially a fair bit more current than you were expecting..... The other one which caught me out was fluorescent lamps, they were 110 volt 58 watt, so quick look assumed ½ amp each, so 16 amp supply should run 32, well to be on safe side, put just 25 on a string. The 16 amp MCB tripped, and I found over 20 amp draw, cure was to use 127 volt tapping not the 110 volt one.
That probably depends upon the direction of the error and, if the meter has been over-reading, how much fighting the consumer is prepared to do! (I imagine that only 'particularly honest' consumers would report a meter which they believed was consistently under-recording their usage!).But if it is found to be faulty, how far back will they go?
Indeed - I would say 'more than adequate'. Any sort of clamp-based device, even if without any wired connection (hence requiring guessing/estimation of voltage and PF) is likely to be adequate for identifying any significant inaccuracies of the supplier's meter, particularly if used over a reasonable period of time (ideally at least a few days).The Shelly EM recommended by taylortwocities above is adequate to test the accuracy of the meter.
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