' Smartmeters'

I am pre-solid state so can someone please enlighten me how these work ?

A 'computation' of volts x amps x power factor via a disc driven by a magnetic field , je comprend.

Via 'solid state' , I do not.

No details of 'how' can be found on the internet.

I presume they are 'solid state' so that they can be turned off by 5G control, as and when required ?

‘Bigclivedotcom’ took one apart. Have a look at that you tube video?

It's all done in an integrated curcuit (IC). Voltage measurement is straightforward, simply a potential divider across live and neutral. Current measurement is done using a current transformer. These are a toroid with a multi-turn secondary. The primary, carrying the current to be measured, is a single wire through the centre of the toroid. A load resistor (usually a few tens of ohms) is connected across the secondary. The current in the load resistor is equal to the primary current divided by the number of turns on the secondary. The current transformer also provides isolation. Voltage and current are read by an analogue to digital converter many times a second. The IC can then calculate power factor, VA, real power and reactive power as well as kWh used. They're much more capable than the old electromechanical meters and, just as important, cheaper to make.

It's also easy to add comms so that the power companies can do you over without you knowing.

Andrew

They use a current transformer to measure the current, rectify the volts to get the voltage, and do a phase comparison to get the power factor, then multiply it all together.

How can you do a phase comparison if the voltage measurement is DC?

All the smartmeter ICs I've used have measured voltage and current as AC signals.

Andrew

They're the thin end of the wedge! Or maybe not quite so these days. George Orwell wasn't so far wrong was he?

I 'get' the method now , thank you.

Combine that with a 'triac' plus comms device to switch it 'off' ,' or similar , and you remotely have the means to control the consumers supply. Nice.

Glad I wrote , I don't want my meter' replaced.

My only comment is to take your own image of the existine meter and it's readings before they rip it out and destroy the evidence. When mine got done they wrongly wrote down the most significant dial and not having any evidence could not correct my bill. Take a photo with a newspaper in view. Stick it in an envelope and post it to yourself. Don't open it but reserve it until you are satisfied with your billing.

regards Martin

I think the current measurement is done by a Rogowski coil printed onto the circuit board, rather than a traditional current transformer.

**LINK**

and

https://www.analog.com/en/technical-articles/current-sensing-for-energy-metering.html 

Stuart

Edited By Stuart Smith 5 on 22/05/2021 12:55:42