230V/240V Question

[ban-all-sheds]

but they are without a doubt related to each other.

No they are not. They are both related to a common factor, namely the load on the system, and it is because of that they will vary together. But if you had a way to adjust the frequency and keep everything else the same, the voltage would not change.

It makes no sense to specify voltage variation limits at the declared frequency.

 

[ban-all-sheds]

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

Because all someone has to do is to drop, or raise, the frequency by 0.4Hz and then they no longer have to stick to a voltage variation not exceeding 10 per cent above or 6 per cent below the declared voltage.

 

[ban-all-sheds]

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?

Or 20V.

Or 500V.

 

[ban-all-sheds]

John, when it says "at the stated frequency", doesn't that implcitely include the frequency tolerance too?

How can it?

There is a declared voltage, and a declared frequency.

The frequency of the actual supply is allowed to vary by up to 1% from the declared frequency.

The voltage of the actual supply is allowed to vary by up to +10% -6% from the declared voltage at the declared frequency.

 

[JohnW2]

deleted - pressed the wrong button!

 

[JohnW2]

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%

That might be what they were trying to say, but it's not what they wrote. It states the permitted variation (around the "declared" frequency) "at the declared frequency". There are clearly using "declared" to mean what people here are calling "nominal". If what you said were correct (that "declared" voltage/ frequency included the permitted tolerance), the permitted voltage range would then be [(declared -6%/+10%) -6%/+10%] - which would be an extremely wide range

Kind Regards, John

 

[PBC_1966]

And as I said earlier, even if it was intended to mean the acceptable frequency range, what would be the point of adding that clause anyway?

If the frequency drops below 49.5Hz or rises above 50.5Hz then the supply is out of overall specification anyway, so why bother to add something which, in such a case, exempts it from adhering to the specified voltage range?

P.S. I suspect the OP has now returned the ceiling lights, had his electricity supply disconnected, and decided to use candles instead!

 

[JohnW2]

And as I said earlier, even if it was intended to mean the acceptable frequency range, what would be the point of adding that clause anyway?

Indeed, and IIRC that was one of the very first points/questions I posted in relation to that regulation.

If the frequency drops below 49.5Hz or rises above 50.5Hz then the supply is out of overall specification anyway, so why bother to add something which, in such a case, exempts it from adhering to the specified voltage range?

Knowing how the minds of those who write regulations sometimes work, it's just occurred to me that being out-of-range for both frequency and voltage at the same time might mean two, rather than one, very large fine(s)!!

Kind Regards, John

 

[PBC_1966]

Knowing how the minds of those who write regulations sometimes work, it's just occurred to me that being out-of-range for both frequency and voltage at the same time might mean two, rather than one, very large fine(s)!!

Maybe! You know, along similar lines I just had another thought: Could that part be intended as a get-out clause for the DNO's If the grid were in such dire straits that it was falling outside the permissible frequency range, the voltages were going haywire as well, and then large numbers of people tried to claim compensation due to the unusual voltages?

"Sorry, we're not required to guarantee any particular voltage once the frequency is outside the specified limits; you'll have to claim from your own insurance."

 

[ban-all-sheds]

Never ascribe to conspiracy what can adequately be explained by incompetence.

 

[PBC_1966]

I agree, the most likely cause of that nonsensical regulation in the legislation is just that whoever wrote it had no technical knowledge and it never really got checked by anyone who did.

 

[JohnW2]

Never ascribe to conspiracy what can adequately be explained by incompetence.

Agreed - although being incompetent does not preclude ALSO being involved in a conspiracy!

Kind Regards, John

 

[PBC_1966]

Perhaps I am paranoid. But that doesn't mean they're not out to get me!