Certainly, I would be quite concerned about allowing that, as I mentioned earlier, but my point was that there was no need to change our existing 240V +/-6% specification at all, given that any new "230V" equipment intended to work down to a low limit of 207V would have been perfectly fine anyway on the U.K.'s existing low limit just under 226V.
If the UK leaves the EU, will the nominal voltage be changed back to 240v?
- Thread starter eveares
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Be that as it may....
Of course there was - the whole point was to make everywhere the same.
You just don't get it, do you.
But everywhere is NOT the same. Other places don't have +10-6% tolerances for a start. I also seem to recall the US is different.
No it isn't. The value of the nominal voltage might be used in a different way to that in which the value of, for example, the nominal diameter of drill bits, but the term is used in exactly the same way.
I have to disagree. Although there are variations in the way in which it is defined statistically (depending upon field/application), whether it's the diameter of a drill bit, electrical conductor, copper pipe, tyre or piston, the weight of the contents of a bag of sugar or coal, the length of cable on a reel, the resistance/capacitance/inductance of an electronic component, the zener voltage of a diode, the amount of drug in a tablet or whatever, the 'nominal' value is nearly always the 'intended'/'expected'/average value of the quantity in question. You may well be able to think of some exceptions but, off the top of my head, I can think of no other situation (other than electricity supply voltage, in most European countries) in which the 'nominal' value differs appreciably from the great majority of actual measurements (in 'specimens') of the quantity concerned.
Kind Regards, John
As I keep saying, the 'on-paper' harmonisation exercise only really makes (or would make) sense if it were part of a well-defined long-term plan to make the actual ('average') supply voltages in all countries 'the same'.
There seems to be somewhat of an irony associated with the 'transitional' arrangements. As Detlef has said, the only reason for the UK not now declaring its supply voltage as 230V ±10% is the fear that there may be some existing equipment which will not function satisfactorily and/or safely at voltages between 207V and 216.2V. Unless manufacturers are somehow 'forced' to do so, declaration of the current UK voltage as 230V -6%/+10% removes incentive to design and produce products for the UK market (and other similar markets) that are happy with voltages less than 216.2V.
Should 'they' not have somehow 'insisted' than manufacturers of products intended for the European market should (from 1995) manufacture them to function satisfactory/safely at any voltage in the range 230V ±10%, even though some countries currently have declared -6% or +6% 'tolerances'?
Kind Regards, John
There are many, many examples where the nominal value of a parameter is the minimum, or the maximum expected value of that parameter. Insulation properties of materials, leakage currents, current transfer ratios of transistors, diameter of threaded fasteners, etc, etc. Even in your list, the average weight of, say, a bag of sugar is usually greater than the nominal weight.
As I posted earlier, at least for industrial products a working voltage range of +10% -15% of the nominal voltage has been required for several decades. Were there not a harmonised nominal voltage, it would be more difficult to express what I have just written.
That's true, and I have already discussed that issue, so maybe I should not have written quite what I just did. As I've said, there are many situations in which interest is 'asymetrical' - as in the examples you quote, including bags of sugar. However, in such situations it is common to quote a minimum or maximum figure (or a range), without or without a 'tolerance', rather than a 'nominal' one.
In terms of bags of sugar etc., I think that, in practice, what I wrote is very close to being true. Although the requirement is that the average weight of a bag of sugar "e-marked" as, say 1 kg, must be 'no less than 1 kg', in practice the average will be very close to 1 kg. If the average were 1.1 kg, it would be foolish of the manufacturer to label it as (and charge for) "1 kg".
The same is at least partially true of characteristics of electronic components such as you mention. Such components (resistors and capacitors etc., as well as semiconductors) are commonly 'graded' on the basis of measured characteristics (e.f. hfe of a transistor) - so a 'nominal' (more likely stated as 'minimum') hfe of, say, 50 does not mean '50 or greater' but, rather, 50-75 or 50-100 - since beyond those ranges it would be assigned a different nominal/minimum value.
Whatever, these discussions about detail are a bit irrelevant. Not only does the 230V 'nominal' electricity supply voltage in the UK not correspond to the 'expected'/'intended'/'observed' voltage, but nor does it correspond to the minimum, maximum, any sort of average (mean, median, mode or whatever) or any other summary statistic of the voltages which are actually supplied. I therefore think that I do challenge you to come up with other examples in which a declared 'nominal' value has so very little (essentially no) relationship to any numerical feature of the observable quantity concerned.
Let's face it, it is surely the range of permitted voltages which actually matters. Would it make any difference if, rather than 230V ±10%, the 'target' figure was stated as 240V -14%/+5.5%? Both represent (approximately) 207V - 253V, and any voltage within that range would be acceptable - so what is the significance in one having a 'nominal' value of 230V and the other a nominal value of 240V?
Kind Regards, John
edit: arithmetic corrected!
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It also makes sense as part of the creation of a single market.
So that will be all the countries who used to have a 220V nominal.
How could they do that if there was not a harmonised 230V ±10% supply?
That is only sometimes correct. In any case, you are agreeing that in such cases the nominal hfe is identical to the minimum.
The nominal weight of a 1 kg bag of sugar is 1 kg. The actual weight is subject to a tolerance that is both numerically and statistically asymmetric. Yes, the tolerance is a smaller value that 10%, but the principle is not altered by that.
Yes, but as I keep saying, this whole 'untidiness' seems to exist because of the apparent obsession with declaring the range of voltages (whether permitted supply voltages or the working voltages of equipment) as "arbitrary nominal ± tolerances", rather than simply declaring the range - which is what actually matters. If, when the 'nominal' voltage was 240V, equipment was required to have a working range of (204V - 264V) and it was then decided this range should change to (195.5V - 253V) why not just say that, rather than change some arbitrary 'nominal voltage', given that the actual voltage supplied to any installation did not change?
Kind Regards, John
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The fact that the nominal value of 230V is harmonised throughout Europe and some other countries.