Well, they've had that 'permission' for a good few years now. They are however governed by the ESQCR, and are more concerned about the effect of 'renewables' on grid stability than they are on the effect of long rural stretches of transmission lines.
If the UK leaves the EU, will the nominal voltage be changed back to 240v?
- Thread starter eveares
- Start date
By declaring that appliances manufactured from whatever date must be suitable to operate on 230V +/-10% perhaps? Or that they must be suitable for operation over the range of 207 - 253 volts? That doesn't mean that the supply in every country needs to have the exact same specification.
Besides, even if the delivered voltage to house may drop as low as 207V and the appliance is required to operate satisfactorily only down as far as 207V, what about voltage drop within the installation? If they were going to account for that, the permissible lower limit for supply voltage would need to be higher than the low limit for appliances, and there would also need to be some sort of standardized maximum permitted voltage drop for installations.
They've had the 'permission' to go down from 225.6V to 216.2V for a couple of decades (and I don't know to what extent they have 'taken advantage' of that); the 'permission' for a further drop to 207V has yet to come - and, again, we don't know to what extent they will/might 'take advantage' of that if/when it happens.
If they want to add a few more properties to a part of their LV network which was fairly 'marginal' without these 'permissions', they presumably would be very tempted to take advantage of those 'permissions' - the alternative presumably being a lot of costly digging and new cables.
Kind Regards, John
Quite.
Indeed - and in the UK we already have 'guidance' about that in an Appendix of BS7671 - the infamous 5% VD 'limit' for all but lighting. That means that if supplies were allowed to be as low as 207V, appliances would have to be signed to operate satisfactorily down to 195.5V (the same as the "Un-15%" figure for commercial equipment specified by stillp).
Kind Regards, John
Industrial John, not commercial.
Exactly what I had in mind. My experience of the DNO area in which I used to live over the last few years of my time there was that they'd reached the point of trying to get away with doing the absolute minimum maintenance and upgrading possible until conditions forced action upon them. I'm sure they'd jump at the chance to get away with allowing distant-end voltages to drop lower during periods of peak demand if they could.
By the way chaps, for those of you not familiar with the Electricity Safety, Quality and Continuity Regulations 2002, you might like to read the following:
(3) For the purposes of this regulation, unless otherwise agreed in writing by those persons specified in paragraph (2), the permitted variations are—
(a)a variation not exceeding 1 per cent above or below the declared frequency;
(b)in the case of a low voltage supply, a variation not exceeding 10 per cent above or 6 per cent below the declared voltage at the declared frequency;
(c)in the case of a high voltage supply operating at a voltage below 132,000 volts, a variation not exceeding 6 per cent above or below the declared voltage at the declared frequency; and
(d)in the case of a high voltage supply operating at a voltage of 132,000 volts or above, a variation not exceeding 10 per cent above or below the declared voltage at the declared frequency.
(3) For the purposes of this regulation, unless otherwise agreed in writing by those persons specified in paragraph (2), the permitted variations are—
(a)a variation not exceeding 1 per cent above or below the declared frequency;
(b)in the case of a low voltage supply, a variation not exceeding 10 per cent above or 6 per cent below the declared voltage at the declared frequency;
(c)in the case of a high voltage supply operating at a voltage below 132,000 volts, a variation not exceeding 6 per cent above or below the declared voltage at the declared frequency; and
(d)in the case of a high voltage supply operating at a voltage of 132,000 volts or above, a variation not exceeding 10 per cent above or below the declared voltage at the declared frequency.
What about car batteries with a nominal voltage of 12V?
Ideally it will be 14-ish in normal usage but cars nowadays will not start (or even try) if it is less than 11V.
Is the reason for 230V not simply, as I maintain, so that we all (in Europe) use the same figures.
Otherwise we would all be Winston and using different values every day and time of day.
Ideally it will be 14-ish in normal usage but cars nowadays will not start (or even try) if it is less than 11V.
Is the reason for 230V not simply, as I maintain, so that we all (in Europe) use the same figures.
Otherwise we would all be Winston and using different values every day and time of day.
Did ESQCR say that prior to the 'harmonisation', or is that simply a statement of the transitional requirement OF that harmonisation?
Kind Regards, John
In that case, it presumably is really necessary to quote 'nominal' values off-charge with no load, off-charge (but charged) with a specified load and on-charge? No single 'nominal' value would be very meaningful.
Kind Regards, John
...but they are 12V batteries.
Is that not the point?
Do you suggest the manufacturers label them, and all other batteries, as - variable?
Is that not the point?
Do you suggest the manufacturers label them, and all other batteries, as - variable?
Use the same figures for what? As I've said, the only safe way to conduct calculations in a situation in which the supply voltage varies is to use the minimum permitted or maximum permitted supply voltage, according to what sort of calculation is being undertaken.
The concept of Cmin introduced in Amd3 of BS7671 goes a long way (with a -6% tolerance) to addressing this for Zs calculations. If the UK tolerance ever changes to 230V ± 10%, the value of Cmin specified in BS7671 will presumably have to be reduced appreciably.
Kind Regards, John
Calculations relating to other parts and values whose ratings etc. have been calculated from the same 230V figure.
Of course it would! What else would you call them except 12V?
No, but all the information appears in the spec.
Whatever, most fully-charged, not being charged (or recently charged) and not on-load "12V batteries" will probably have a voltage of 'around 12V'. What proportion of UK installations would you say have electricity supplies which are 'around 230V'?
Kind Regards, John
No, and no. It is the UK legislation.