OT: Smart meters...not very!

http://www.theregister.co.uk/2017/03/06/smart_meters_prove_dim/
Oh dear, how sad, never mind.
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It happens that The Natural Philosopher formulated :

I wonder why they mentioned 3ph right at the beginning of that, then swapped midway to domestic supplies which were presumably single phase?
I have tested both of my meters just as thoroughly as possible and found no obvious calibration errors. The rest of the Smart is sadly lacking.
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I don't understand why the measuring part of the meter isn't exactly the same as the previous style of digital meter, like wot I have on my property right now
http://isswww.co.uk/landis-gyr-5235a-100a-single-phase-non-pulsed-credit-meter?gclid=CjwKEAiA0fnFBRC6g8rgmICvrw0SJADx1_zA4nj232dsO5zHGHH7-0T3L145qvFgWgpxart7hBfqJhoCPrPw_wcB
or perhaps these read wrongly as well
tim
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tim... pretended :

No meter can measure equally accurately in all conditions, so all will read wrong to some extent, which is why they allow a tolerance of accuracy. They are suggesting these all electronic Smart Meters can miss the sudden surges in demand, I would suggest the older mechanical meters missed even more.
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On Tue, 07 Mar 2017 16:45:01 GMT, Harry Bloomfield

IIRC, the disks on the old mechanical meters would rotate even under no load until they reached a certain part of the disk and stopped. So I guess even a mometary draw would cause one revolution.
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On 07/03/17 16:52, Caecilius wrote:

No. I dont think so at all.
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With no load where does the power come to drive the disk around?
Tim
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wrote:

From the voltage coil.
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Caecilius brought next idea :

My understanding is that both voltage and current coils need to be active, for the disc to rotate. Only one coil active, means the disc will be effectively braked.
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Caecilius submitted this idea :

Reading up a bit on this subject, there is a meter fault known as creep, where the meter will continue to turn slowly, despite no load. That is not the same as the disc doing a full revolution or completing a revolution, after demand has ended.
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On Wednesday, 8 March 2017 05:07:30 UTC, Harry Bloomfield wrote:

There was permanent magnet to stop this sort of thing which was caused by the meter working as an induction motor due to the voltage coil.
The magnet also acted as a brake stopping the disk almost immediately when the current went off.
This gave rise to the urban myth that putting a magnet on top of the meter slowed it down.
http://iopscience.iop.org/article/10.1088/0950-7671/15/6/303
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On Tue, 7 Mar 2017 23:35:38 -0800 (PST), harry

The permanent magnet provides a braking force that's proprotional to the speed of the disk. As you say, it's stops the disk spinning like an induction motor and reaching 3600 rpm or whatever.
But it will have virually no effect at low speeds, because the eddy currents that it induces get lower as the disk spins slower. So I don't think the permanent magnets stop disk creep (if it's ever actually a problem in the first place, which I'm starting to doubt now).
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On Wednesday, 8 March 2017 14:24:05 UTC, Caecilius wrote:

ISTR hearing about it when I was in the electricity board and it happened sometimes if the meter was not installed level. Never actually saw it.
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On Saturday, 11 March 2017 07:32:57 UTC, harry wrote:

I have a fish tank aerator works on the principle.
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On 07/03/17 23:26, Caecilius wrote:

Which has no effect unless there is another field to react against, from the current coil.
Think about it: Which way would a single coil drive the disk? And why?
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wrote:

They sometimes (don't know how often, I've only seen one example) have a shading coil which provides an additional magnetic field that's out of phase with the voltage coil. I believe this is designed to just overcome frictional losses so that very small loads are measured. But sometimes (again, don't know how often), this makes the disk creep. So some disks have a hole or slot drilled into them at a certain position, and they will creep round to that point at zero load.
I've only seen one example though, and that was a very old 240v single phase meter back in the 1970s (the meter would have been much older than that). So I could be talking about a very rare behaviour on a particular type of electromechanical meter.
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On 08/03/17 14:18, Caecilius wrote:

That's a good point - if there was a shading coil, and it was mis calibrated, I guess that would do it.

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On Wednesday, 8 March 2017 07:47:00 UTC, Tim Watts wrote:

It would not be self starting but would run on once it was going. I have a fish tank aerator works on the principle. Drives a twin cylinder pump
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Caecilius has brought this to us :

I have never seen that and I would doubt it.
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On 07/03/17 19:06, Harry Bloomfield wrote:

Me neither. They stop where they were last seeing current flow.
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