In message , Roland Perry
writes
In message , at
12:40:27 on Sat, 7 Mar 2015, Mike Clarke
remarked:

For example, if you see a 2kW spike that lasts around 90 seconds, you
can hypothesise that it's an electric kettle or a toaster. And if it
happens during Coronation Street advertising breaks, more likely the
latter (and will also correlate fairly well with watching ITV).

Yes but this would require continuous real time analysis,

The analysis can be later.

probably too complex for a design that just sends power usage for each
30 minute period.

Yes, it requires the power usage to be transmitted much more often than
that.

Other appliances will have their own characteristic components.

The TV programme thing is also related to being able to filter out a
pattern where the power consumption of the TV varies with the brightness
of the picture, and seeing if any of the contemporaneously broadcast TV
channels has a likely candidate.

These variations will be very small compared to total usage by
everything else in the house.

Every radio receiver is picking up programmes which are very small
compared to the total RF arriving on their aerial.

I doubt if smart meters will have that sort of computing power.

Me too. This is something which I think has to be done centrally.

And likely to be unable to sort out what's happening if 2 TV's are in
use in the house at the same time with people watching different
channels.

That's no different to a radio being able to tune into either of two
weak transmissions.

And as to the claim "track when you toilet light goes on" - it's going
to be a very smart meter to know the difference between the light in
the toilet and any other light in the house.

There's probably some journalist licence there. It could of course be
just as likely as the light in the cupboard under the stairs, assuming
you visit that briefly several times a day.

What I'm not convinced about, however, is whether the smart meter in
your house [one of which was shown on Breakfast TV this morning] can use
those sorts of techniques to tell you how much power your deep freeze is
using

That would probably depend the use of smart devices capable of talking
to the meter.

Hmm, they appear to be promising this data without me having to upgrade
my appliances.

Meanwhile, one of the hiccups with the scheme is apparently that telling
people what the cost of their consumption is *now* [I have had a
clamp-on meter for that for over five years now] results in them using
*more* electricity not less.

For example mine is telling me that my current consumption [the
background on a Saturday mid-morning] is ~600W at a cost of £1.77/day.

Exactly. instantaneous values are pretty well useless for overall cost
calculation purposes.

They are quite useful (eg my quarterly bill is fairly consistently
about twice the displayed cost of my base load), it's just that telling
someone how much it's costing for *today's* consumption gives such a
low figure they are likely to think "so what".
Which is precisely the technique used by our local Crime Commissioner to
sell an increase in the Police part of council tax - it's less than the
price of an apple a day.
--
bert