EVSE questions

Hi, I would be asking exactly which indent of 722.411.4.1 their O-PEN device/technology complies with, and if it works in ALL cases of a broken PEN conductor. Then how a designer/installer ensures that they are themselves complying with BS7671 if the device/technology has no product standard?

table 5.2 of C.O.P has some BS EN  numbers to check for but does complying with one or more of these satisfy indent iii iv or v?

A few contributors on here will likely help with this? 

Maybe this is something I’ve missed and is straight forward??

cheers

Then how a designer/installer ensures that they are themselves complying with BS7671 if the device/technology has no product standard?

I don't see a problem on that score  - BS 7671 only requires compliance with a standard where a suitable standard exists - there isn't a standard then it's just down to agreement between the specifier and installer (reg 133.1.2).


   - Andy.

Andy, the load management idea is impossible without central control

Er, why? It seems perfectly feasible to manage demand within a site to stay within agreed supply limits without any central control. As for responding to tariffs - we've had that in principle via radio switched for donkey's years - doesn't seem to have caused the sky to fall.

   - Andy,

Demand management could be done as simply as by allowing the mains frequency to droop at times of overload, and raising tarrifs on that basis, and having a little detector in things like water and storage heaters that detect this and give the user an option to load shed and save some money. No big central computer or complex and easily compromised network required -  that would be the 1960s solution.

I think that neither of you has analysed the problem properly. I am not talking about that kind of management. I have a 1 MVA supply, Clearly, I would not add enough chargers to exceed my supply. The kind of demand management I am talking about is to match the car charging to the wind and solar supply limits of the entire grid. There is no point whatever in running an electric car unless it is solely charged from "renewables", because the car/charging system is less efficient than a fossil-fueled car by itself, and miles more expensive to make and provide infrastructure to run it.


There are many reasons why the supply frequency is controlled within fairly narrow limits, and it is important that doesn't change. Using frequency as a demand signalling device wouldn't work. It is already being made less stable because of reduced mechanical inertia, and there is no instant control mechanism available to stabilise it or control it anyway.


All of this assumes that EV drivers would be happy that they had no control of the charge in their car. Someone planning a long trip would be at the mercy of the wind or light as to the length of stops for charging. Imagine 5 days with no wind in winter. A car could take days to charge as almost no renewable power would be available, that really is rather a long stop at the Motorway services. The whole plan with electric vehicles assumes, in my view falsely, that they will be used for short trips locally, and that Holidays will be taken by bicycle (or very locally). It also assumes that vehicle charging will be provided by someone else at zero cost to the EV owner and that fossil fuel-derived electricity may be used to power the car most of the time. In fact, the whole renewables "free electricity" plan is so flawed that it must have been dreamed up by an Oxbridge graduate in medieval architecture. No Engineer of any ability would contemplate such a system if they had to be responsible for the result and cost. The whole lot seems to mimic Crossrail and HS2, astronomical cost overruns, extreme lateness, and probably non-functionality when completed because the capacity planned is no longer correct. It sounds awfully like the Electricity system at the moment.

Going back to the OP, we have another Unicorn device here. If we have no performance standard, or one which has not been verified by disinterested parties, we have another problem looming. The AFDD has this problem, and this idea is the same. Detecting that a CNE connection has failed is very difficult because there is no reference potential available, and using a TT type connection as reference has many problems which we have discussed many times. IF the supply is 3 phase, we may use the 3 phase/neutral voltages to recognise a break under some fairly ideal conditions, but load power factors and powers may seriously sway the results so as to make them unreliable. With a single phase supply there is no isolated Earth reference available, and thus it is probably impossible to detect a CNE break. If someone comes up with a non-TT method I would be interested to analyse it fully and the Patent application would be unlikely to succeed if it could not be shown to work under any possible conditions, by demonstration.

Lyle, I would be most interested to hear what the training says. Perhaps you would PM me when you have received it. Good luck.

Kind regards

David

So Jon, Steward, you are saying that it wasn't over 30°C for a week in the Arctic circle this year and that the Artic ocean has had decreasing ice cover every year.

The problem is that the excess heat going into the atmosphere is resulting largely in warmer seas and melting ice. The actual temperature rise is very modest - for the moment.