"Steve Walker" wrote in message
news
On 07/03/2017 16:40, dennis@home wrote:
On 07/03/2017 15:42, Steve Walker wrote:

In todays news, lab tests of a number of different types of meter have
shown overreading by smart meters when led lighting or dimmer switches
are used - 100s of percent in some cases!



Link please.

http://www.theregister.co.uk/2017/03...ers_prove_dim/


That website says that a 'Rogowski Coil' is used to measure the current, and
gives a link to a description of this
http://www.pemuk.com/how-it-works.aspx. The thing that struck me was that
although the described circuit certainly measures average alternating
current of any waveshape, there's nothing about RMS value, or combining with
voltage waveform to get true wattage.

I would imagine that smart meters would have a completely different circuit
arrangement, probably involving fast analogue to digital converters
monitoring both current and voltage, and software to do the multiplication
into true power. There could be many causes of error if current waveforms
are encountered that have not been catered for in the design.
--
Dave W