230V/240V Question

[ban-all-sheds]

I really don't see what analogy you're trying to draw here.]Stating that, for example, "The boiling temperature of water is 100° C" does not have a precise meaning unless the pressure is specified, just as "The supply voltage shall be X ±10%" does not have a precise meaning unless the frequency is specified.

Nonsense.

The mechanism which causes BP to be related to pressure can be explained.

There is no mechanism which causes voltage to be related to frequency. For sure, if things have gone so pear-shaped that the frequency limits have been breached then it's likely that the voltage ones have too, but that does not mean that there is a causal relationship between frequency and voltage.

 

[PBC_1966]

There is no mechanism which causes voltage to be related to frequency. For sure, if things have gone so pear-shaped that the frequency limits have been breached then it's likely that the voltage ones have too, but that does not mean that there is a causal relationship between frequency and voltage.

Exactly.

So what is the point of that clause in the legislation? Is it supposed to mean that the stipulated voltage limits aren't applicable if the frequency has gone outside limits? Perhaps, but why bother with that? If the frequency limits have been breached then the supply requirement as a whole has been breached anyway, so why write in something which would then mean that voltage limits haven't been violated? It makes no sense.

And let's face it, if the grid frequency has dropped below 49.5Hz there's a pretty good chance that a lot of people will soon be seeing a supply voltage of zero anyway.......

 

[stillp]

Both wrong. The frequency and voltage of the Grid are inextricably linked. The relationship is not causal, in that a change in frequency will not of itself lead to a change in voltage, but a change of grid loading will result in a change of both voltage and frequency. How the voltage and frequency are numerically related in not easy to compute, and will vary according to the characteristics of the Grid at the location in question, but they are without a doubt related to each other.

 

[JohnW2]

Both wrong. The frequency and voltage of the Grid are inextricably linked. The relationship is not causal, in that a change in frequency will not of itself lead to a change in voltage, but a change of grid loading will result in a change of both voltage and frequency.

I think that everyone has acknowledged that, but it does not make it any more reasonable to specify voltage limits at one frequency, but not any others.

Not only is the relationship between voltage and frequency not a causal one, but nor is it necessarily a consistent one - since, as you went on to say, it "...will vary according to the characteristics of the Grid at the location in question". One therefore cannot say/assume that any particular frequency implies any particular voltage, or vice versa.

Kind Regards, John

 

[stillp]

Both wrong. The frequency and voltage of the Grid are inextricably linked. The relationship is not causal, in that a change in frequency will not of itself lead to a change in voltage, but a change of grid loading will result in a change of both voltage and frequency.

I think that everyone has acknowledged that, but it does not make it any more reasonable to specify voltage limits at one frequency, but not any others.

Not only is the relationship between voltage and frequency not a causal one, but nor is it necessarily a consistent one - since, as you went on to say, it "...will vary according to the characteristics of the Grid at the location in question". One therefore cannot say/assume that any particular frequency implies any particular voltage, or vice versa.

So why can you not see the logic in declaring the voltage limits at a single frequency?

 

[JohnW2]

So why can you not see the logic in declaring the voltage limits at a single frequency?

Because if one does that and the prevailing frequency is anything other than that 'single frequency', the regulation gives no indication of what the voltage limits then are!

Kind Regards, John

 

[stillp]

BUT THAT DOESN'T MATTER!

 

[PBC_1966]

So from the statutory requirements point of view, so long as the supplier makes sure the frequency is always either above or below 50Hz, never exactly 50Hz, it can get away with delivering only 200V to you, because the limits don't apply?

 

[JohnW2]

BUT THAT DOESN'T MATTER!

I really do struggle to understand your position. Let's try an analogy ...

Let's say that was a law/regulation which said (and only said) that the acceptable range of ambient temperatures in some working environment was, say 18 - 22 °C when the relative humidity was 60%. Today the relative humidity in the workplace is 45% and the temperature is 25 °C. Is the employer complying with the law/regulation or not?

Kind Regards, John

 

[stillp]

I'm sorry you can't understand it John, but it doesn't really matter.

 

[JohnW2]

I'm sorry you can't understand it John, but it doesn't really matter.

It doesn't matter to me, since I don't generate, distribute or supply electricity, but I'm sure that it matters a lot to some people. If, as seems to be the case, you can't answer my recent question as to whether or not the employer I described would be complying with the law/regulation, you really ought to understand what the problem is - with that analogy, and with electricity voltage limits.

Kind Regards, John

 

[stillp]

If, as seems to be the case, you can't answer my recent question as to whether or not the employer I described would be complying with the law/regulation,

I can, but I won't.

 

[PBC_1966]

I can, but I won't.

Then perhaps you can tell us what the statutory voltage limits are at a moment in time when the frequency happens to be 49.8Hz ?

 

[JohnW2]

If, as seems to be the case, you can't answer my recent question as to whether or not the employer I described would be complying with the law/regulation,

I can, but I won't.

You must have mystical powers, then, as well as being stubborn!

Kind Regards,, John

 

[Gerrydelasel]

John, when it says "at the stated frequency", doesn't that implcitely include the frequency tolerance too? I would assume it does. i.e. the voltage is specified as 230V +10/-6% at 50Hz +/-1%