On Wednesday, May 1, 2013 12:21:38 PM UTC+1, wrote:
On Wednesday, May 1, 2013 11:11:28 AM UTC+1, whisky-dave wrote:

On Wednesday, May 1, 2013 12:33:51 AM UTC+1, wrote:

On Tuesday, April 30, 2013 11:35:49 PM UTC+1, The Other Mike wrote:



If the government keep their stupid fingers out, it won't be long before appliances with this feature are available for an extra £5.

No you'll be entered into a free prize draw....



An 8 bit cpu can respond to frequency,



Not that easily, and I doubt using that method would be very successful..



its not hard to divide the clock frequency down to 50Hz ..
But you need a dedicated clock you can;t use the average MPUs clock as it's too inaccurate, you need a proper RTC, you do know that computers keep pretty crap time unless they get it from a server.
You wouldn;t use that method anyway as you need to mearuce the actual frequency of teh main not simulate it.


and time the period from local zero crossing to mains zero crossing, and log the latest value to see how far it moves.

Not necessary.




Far better to have teh aplience switched off on demand from the suplier than wait for the frequency to alter which would be difficult to measure cheaply.



well, thats what checking the frequency achieves. How would you do it cheaper?

Measure the frequency at the power station and if it's condered that power needs reducing lower the overall voltage supplied to the grid.
If yuo really need to switch things off then measure the frequency of the grid and if it's below what you see as a miniumium then send a single to turn off particular devices that are in yuor home that the smartmeter recognise.




Be silly to have to measure the frequency of every device.



Either you measure locally or decide centrally and communicate. Do you think 2 way communication's cheaper?

Yes.
Measuring low frequecies accuratly is more difficult than you think.
What you have to do is count cycles in one second yuod get perhaps 47 or 53 so you need to average it out especailly in times of high or low demand.
So you need to sample it for at least 10 seconds to giove you 0.1 resoultion and in that time the situation can change.

Anyway it would be cheaper to have just one device measuring frequency rather than every electrical device each reading it. If I were designing such a thing it'd use teh smart meter to measure it rather than install the ciruitry in my kettle and fridge.freeze, TV cooker shower , washing machine, coffee maker storage heaters fires hair dryer etc.....

What I'd get manufactiers of such devices to do it allocate a specific number to each product a bit like a MAC address which my smart meter can locate and be able to either just switch off/on or reduce it's power.

idf all 2KW+ kettles had a 1/2 power switch then my first try would be to turn those kettles is 1/2 power them, I wouldn't turn off motors or mmoving things such as food blenders.






and send the appliance serial number down the wiring now and then, and the power co software will automatically knock £1 off the bill.



Too much hassle and no need for it.



The user needs some reason to spend the cost of the control unit. If I were offered 20% ROI I'd buy, for a prize draw I wouldnt.

You don;t need to you make it cheap enough that no one would bother or you make it illegal to sell products without such things. We do this in the name of H&S, you can't normally buy appliences without leads, you have to buy them with the product or buy them seperatly.

I remmber the days when buying electrical equipment you HAD to purchse a lead or plug and put that on yuorself. Nowadays that's not possible for most people you can;t go and buy even a £5 kettle without a moulted lead.
You can't say IO'm not buying an electrical product that comes woth a free lead because i have plenty. I have about 150 IEC leads I'm not using in a box.