final connections

[dingbat]

My college lecturers must have been dinoaurs, cos from 1987-1991 they used 240 in calcs. Wonder why?

Becasue City & Guilds still use 240, to this day. The principles are still the same, but you'd think they'd make the effort, wouldn't you?

 

[Stod]

My college lecturers must have been dinoaurs, cos from 1987-1991 they used 240 in calcs. Wonder why?

Because the supply voltage in the UK really was 240V.

The privatisation sale prospectus, dated 21 November 1990, page 59 says “The vast majority of consumers receive electricity at 240V, but large industrial and commercial consumers are generally connected at higher voltages.”

To be fair, FWL said that the CEGB had adopted 230V in 1982, not mentioning the Area Boards. Odd, that, because the CEGB only had a transmission system and that operated at 275kV or higher.

 

[Big_Spark]

Stod, the reason for mentioning the CEGB rather than individual boards is because they were THE state operated quango, whatever you want to call it, that actually decreed the voltages supplied by the Boards, and as susch they dealt with the CENELEC back then.

Obviously things have changed a huge amount in the last 20 years, the supply voltage, as an average, is normally about 237.8V ac rms, or 417.6 V ac rms.

The fact that the C&G still do not adopt the 230V rating is a matter for th industry to address as it is incorrect and needs to be addressed.

Facts are facts, if you do not believe me than I suggest to contact CENELEC direct and chat to them. It is not my fault if there is a typographical error in BS7671 caused by arrogant British attitudes from the BSi and IEE.

 

[Stod]

Stod, the reason for mentioning the CEGB rather than individual boards is because they were THE state operated quango,

And I thought that it was the Electricity Council's job to over view the CEGB and Area Boards...

Hey - that "typographical error" on page 13's a big one! here

 

[ban-all-sheds]

And I thought that it was the Electricity Council's job to over view the CEGB and Area Boards...

That may well be the case now, but not then.

 

[Big_Spark]

And I thought that it was the Electricity Council's job to over view the CEGB and Area Boards...

Hey - that "typographical error" on page 13's a big one!

That date is the date when the new voltage was adopted by the BSi and as BS7671 was a BSi publication then, that is why the date is Pre-1995..it is silly, I agree, but that is what it is.

Electricity Council?? Who the hell are they, do you mean the region supply companies as they were then like London Electricity, Eastern, Southern etc?

If that is the case then they are down the pecking order, and they still are.

The CEGB and BNFL are the two most powerful organisations that existed in those days, the management order was arranged thus.

CEGB > BNFL >Regional Suppliers Association > Regional Suppliers

The RSA was a simply a mouthpeice that did the negotiating, but in the structure that existed it had more power than the RS's.

The structure has changed today, with National Grid at the top of the list and the Generators just below that, although the generators still dictate the final voltage supplied to consumers.

 

[AdamW]

Seeing as we are/were on the subject of mains tolerances, why has no-one pointed out the +/- 1% tolerance on the mains frequency? After all, voltage is voltage but phase and frequency problems would not do much good for the national grid!

Everything I have ever read (admittedly on the internet) where someone has measured supply voltage gives results nearer 240V than 230V.

 

[plugwash]

the situation with mains voltage is what i would consider fake harmonisation

basically they took a voltage half way in between the two historic standards 220 and 240 and made the tolerance wide enough that both of the historic standards were almost completely contained in the new standard

 

[ban-all-sheds]

the situation with mains voltage is what i would consider fake harmonisation

basically they took a voltage half way in between the two historic standards 220 and 240 and made the tolerance wide enough that both of the historic standards were almost completely contained in the new standard

Yup, just as we signed up to 230V +10% -6%, so the 220V countries signed up to 230V +6% -10%, and then in 2008 (maybe) we'll all sign up to 230V +/- 10%. But unless the suppliers in the UK want to lose 8% of their revenue they still won't drop below 240V. I just hope that lamp manufacturers continue to make products rated at 240V...

As for the frequency tolerance - aren't they supposed to arrange for the mean to be 50Hz, i.e. if the frequency drops for a while then they have to run at >50Hz for a bit so that clocks etc catch up?

 

[Stod]

Ban is too optimistic.

It's Christmas for the Distribution Network Operators like Electricite de France (London and Eastern). Their cable sizes are nearly always limited by the voltage drop rather than the current rating. They stand to save a lot of money by doubling their permitted voltage drop - more than the 4% revenue loss (regulation won't allow 8%)

Network design will be to use the full tolerance to maximise DNOs' profit. If you are on a new estate and if you're at the end of a feeder, expect variations from 207 to 253 volts.

By the way:

Facts are facts, if you do not believe me than I suggest to contact CENELEC direct and chat to them. It is not my fault if there is a typographical error in BS7671 caused by arrogant British attitudes from the BSi and IEE.

I did better, FWL! How about The Electricity Supply Regulations 1988, clause 30 (1) (c) see here - quotes 240V as the standard voltage. Guess you got it wrong.

 

[ban-all-sheds]

..(regulation won't allow 8%)

What do you mean by that?

 

[ban-all-sheds]

FWL - Look in BS 7671 : 2001 Amendment No 2 : 2004, page 13 and you will see that 230V was introduced on 1/1/1995.

Or do you know better than BS 7671?

Yes I do

CENELEC Harmonisation Document HD193 was published in 1982, with effect from 1st January 1983. This required all signatory states to harmonise their respective power generation networks to 230 V ac rms +10% -6%. The UK was a signatory state.

And HD 472, which is the standard that covers supply voltages was published in 1988. It came into force in this country on 1/1/1995....