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dazdaz
5th Sep 2008, 22:34
Maybe more enlightened readers may know why this would not work to reduce power output from the generating companies and thus reducing electricity bills for UK consumers.

Lets presume an introduction of all electrical appliances (over x years) in the UK to run on 125v (as USA) you might be thinking, so how do I plug the appliance in to my 250v socket? You still do, but via a transformer that reduces the volts down to 125v to run your new (125v) reduced powered electrical products.

Or am I missing something:hmm:

Daz

.

Dan D'air
5th Sep 2008, 22:38
You could try asking Westlakes, as I get the impression that he knows a thing or two about electrickery.

Loose rivets
5th Sep 2008, 22:39
Yes, you really haven't thought it through have you.:8

Darn! that dumb 120 second delay spoiled One's snappy response :ugh:


Work done, amps X volts ie power in Watty things.

Wire has to be much thicker to carry higher current (amps) Therefore you have to rewire the United Kingdom. Copper is $8,000 per tonne right now (unless you're Chinese, then it's $400. ( Cost they had the sense to buy a copper mountain's mining rights.)

Then there's the energy involved in doing all this. Mankind will have become extinct by the time all this is paid for.

ORAC
5th Sep 2008, 22:42
Or am I missing something yes, the laws of physics. The device draws the same power regardless of the voltage, V=IR.

For transmission purposes 220V is better than 110V.

dazdaz
5th Sep 2008, 22:49
ORAC
So why don't one of the biggest manufacturing nations in the world (USA) run on 230/220v?

Daz

Gelande Strasse
5th Sep 2008, 22:54
.....and 440Kv is much better which is why transmission over large distances are at the high voltage end. IR losses increase as the voltage drops. Transmission distances at 240v really are short, you won't have to travel far to find your local transformer.

My 2p

GS

west lakes
5th Sep 2008, 22:59
ORAC has the main bits
The amount of power used is the same regardless of voltage so a 13A socket at 230V will give you (roughly) 3kW (it's actually 2.990kW)
For that sort of load at 125V you would need 24amps.
The biggest problem will be the increased costs for the customer, pick up any charger or power supply (mobile phone, laptop etc.) and it will be warm to the touch. All transformers have internal losses that are evident in the form of heat, the losses are of two types fixed (iron losses) and load related (copper losses).
So for a given output say 24A at 125V you actually have to put in more than 13A at 230V (dependant upon the efficiency of the transformer) which you as the customer will pay for on your leccy bill.
A typical small unit is only about 85% efficient so it will cost you 15% more to operate a device at a lower voltage via one of these.i.e. a 3kW output could need a 3.450kW input. or 450W of losses equal to 4 1/2 100W bulbs
Whilst the copper losses are dependent upon load, the iron losses, which are fixed, occur even if there is no load being used

arcniz
5th Sep 2008, 23:05
So why don't one of the biggest manufacturing nations in the world (USA) run on 230/220v?

In effect, they do. Typical new-build (going back to maybe the 50's) household wiring in the US is a 230-240 volt supply, derived from a distribution transformer (on a pole or in a bunker) nearby that steps it down from an intermediate distribution voltage of around 660.

The 230 volts is split into two 'phases', or arms, that are wired to 115v outlets through along with the center-tap or "neutral" wire. Some 115v circuits are on one phase and some are on the other. Heavier loads are connected between the two 'hot' phases and so are supplied with the full 230v.


i---------- 115vac -----------------
C
C
C
I---------- neutral aaaaaaaaaaaa>>>>> 230vac
C
C
C
i---------- 115vac -----------------

west lakes
5th Sep 2008, 23:08
The maths of the use of high voltages are actually quite easy, the voltage drop in a cable is solely dependent upon current,the cable cross sectional area and the conductor material (there are other factors that limit cable maximum loads such as heat rise and dissipation).
So if for example you are going to lose 100V over a given length of cable at a certain load, the actual voltage loss is a smaller value (so more volts left at the end) in relation to a higher voltage.
So at 230V you soon get outside statutory minimum voltage (216V)
at 400,000V you still have 399,900. This can be adjusted by the transformers in the system up to the HV to 230V transformer so that the limits are maintained

ORAC
5th Sep 2008, 23:12
So why don't one of the biggest manufacturing nations in the world (USA) run on 230/220v? History - Edison started off using DC at 100V, when the change was made to AC it was cheaper to stay with 100V as the cost of rewiring was too high and would have taken much, much too long to amortize. See here. (http://en.wikipedia.org/wiki/Mains_electricity)

ChrisVJ
5th Sep 2008, 23:32
One of the bugbears of the US system is that the sockets are 15amp 125v. If you wished to use 30amp you would have to increase the size of the wire used in house wiring and even from one size up (used for 20amp circuits,) it becomes stiff and difficult to manage and to connect inside outlet boxes. Because we only have 15amps at 125v we are stuck with fan heaters, for instance, that have a maximum output about half that in the UK. (Essentially gutless.)

As a woodworker I also find that several types of power tools are lacking in power compared to UK as well. Not small stuff like circular saws , but planers and table saws are much less effective comparing like to like, (ie Amateur equipment to A E.)

Wiring up a supply for 240v also has it problems. For instance baseboard heaters are mostly wired that way but ( in Canada anyway) if they do not have an indicated "Off" position on the thermostat they can be wired with only one pole open. That means one can turn off at the thermostat and then find that the other end of the cable is still live!

I miss (but very little) having switches on outlets too. Tedious having to go round unplugging everything when I used to be able just to flip the switch.

The significant advantage, according to the proponents, of 120v is the lerssened risk of electrocution. Doesn't always seem to work though and the belts hurt just the same here too.

dazdaz
5th Sep 2008, 23:32
Thanks for your feed back guys. Was just an idea and I now stand more informed of my original post.

Daz

Bushfiva
6th Sep 2008, 02:11
Just to emphasise what everyone else has already said, current goes up as potential goes down. Energy loss increases with the square of the current and shows as heat.

To give a concrete example, I'm in a 100V area (not even 110V). There is nothing on the market equivalent to European kettles boiling a liter of water in a minute. The most powerful vacuum cleaner one can buy is around 990W.

My parents' European house has 6 breakers, if I remember correctly, behind a small cover. My small apartment has 18 breakers, rated at 20 to 40 amps. Every cord on every device runs slightly warm to the touch. Power outlets also tend to be warm to the touch.

200V circuits are now available in many buildings to drive air conditioning and the larger white goods, but for example you can't get 200V plasma TVs, irons, kettles and so on.

At my previous apartment which was a 1970's building, I couldn't run any two high-power devices at the same time. For example, only one of two air conditioners, but neither of them with the clothes dryer.

100V is a pain in the bum.

barit1
6th Sep 2008, 03:30
In the US, most large appliances DO use 230v as arcniz has diagrammed. For smaller ones, from table lamps to cellphone chargers, there's little difference to be noticed.

Actually, to achieve some real economy, it would be wise to increase the AC generation/transmission frequency. That's why aircraft converted to 400 hz sixty years ago. This reduces the iron losses (see west lakes' post) and/or permits lighter iron cores. The only problem is any AC motors (A/C, refrigerator, washer, mixer...) would need redesign.

Loose rivets
6th Sep 2008, 03:46
One is mindful of 2 pi f L old chap. Line inductance at 400 hz. we'd be heating the countryside.

seacue
6th Sep 2008, 06:16
The 400 Hz whine from slightly loose iron cores would drive people mad. Aircraft are so noisy that it doesn't matter. There is a story that the US Navy tried an 800 Hz system on a small ship to save weight. They had to abandon the idea since the crew couldn't stand the ever-present whistle.

vapilot2004
6th Sep 2008, 07:06
There are times my ears ring with that 400hz sound or some harmonic of it hours after a flight when I am in the car or somewhere quiet.


ORAC's electric link led me to this bit of amusement > Le Chatelier's principle which states:

"Any change in status quo prompts an opposing reaction in the responding system."

tony draper
6th Sep 2008, 08:12
Good grief man are you mad! twould take the womenfolk twice as long to do the ironing, we chaps would have to wait ages for uz dinners.:rolleyes:

dbee
6th Sep 2008, 08:34
In the US, they went for 60Hz instead of the 50Hz in Europe. Some gadgets will not mind - but the clock on your cooker certainly will! 60 is a bit further away to human body damage. Give me 240V and 60Hz anytime ! --- dbee

ZEEBEE
6th Sep 2008, 08:59
On one of our Cooking shows on TV, the presenter was heard to advise the audience

" And ladies, remeber that our microwave ovens are all made in japan and because we have twice the voltage, we have to HALVE the reccomended cooking times "

Apparently the TV station was flooded with complaints as to why their chicken roast or whatever came out raw! :ugh:

Joey Q
6th Sep 2008, 10:13
what sick bastard makes chicken roast in the microwave??
You cant do much but applaud the stupidity of that kind of advice

Aaaaaaaaaaaaaaaargh!
6th Sep 2008, 14:14
100V is a pain in the bum.That's nothing. My house has aluminum wiring :*

tony draper
6th Sep 2008, 14:20
There were still some houses in South Shields on 100v DC in the late fifties.
:uhoh:

Aaaaaaaaaaaaaaaargh!
6th Sep 2008, 15:44
Must've been a bastard to load all those Doube As

ORAC
6th Sep 2008, 16:08
Up to 1937 the UK had a series of interconnected regional grids running at various voltages and currents, only the backbone was standardized.

I have a UK standard 2514 Philips (http://www.btinternet.com/~ALLAN.ISAACS/philradio.html) 1927 radio which has an 118V, 40/100Hz power supply.

Loose rivets
6th Sep 2008, 17:05
That's nothing. My house has aluminum wiring


Aaaaaaaaaaaaaaaargh! That's seriously bad news.

If you ever rip it out, save some for me. You can use the sheathing for 'Sistoflex' Mmmm, got that word from the 50s. But short lengths for handy sheathing. The wire itself is very useful for making rustproof hooks, wire locks etc., I use loads of it for odd jobs, especially in the garden.

Should you need to terminate / join Au and Copper wiring, be cautious about the junctions. Since I can only get part of my son's house done at a time, I've had to do some temporary joins. I use a separate box for each pole...and twist several inches of the disparate metals together so that the contact surface is waaaaaaaaay beyond spec. The substances that are supposed to improve the conductivity on a standard twist, are to me, extremely suspect.

New wire is as issue now with copper prices being so high. Get a very definite standard by a well known manufacturer.

BTW...I'm down the road again for a while.

Loose rivets
6th Sep 2008, 17:17
Looking at ORAC's pictures, reminds me of my early days as a radio and T/V apprentice. Wooden plugs...I've still got some of them in me boxes of tat.

I can still remember the smell of the black potting tar-like stuff and the increasing difficulty of getting some of the valves.

As Drapes says, some towns still had DC in some of their streets, as I found to my cost when I plugged in PYE's new issue quick-heat soldering iron. That must have been 1959 !

I lingered outside a building in Colchester a few weeks ago. It used to house Rota, a supplier for the six or so R-T/V-Electrical shops in the town. It used to buzz with activity 8 hours a day. Sometimes I would be sent there 3 or 4 times a day just to get a valve. Stocking the rarer ones was beyond the means of some businesses.

FlyingOfficerKite
6th Sep 2008, 17:22
As someone who is involved with the utilities industry, bear in mind that there are over 17,000 sub-stations in the North West of England alone which provide 240V AC stepped down, in stages, from the 132kV grid sub-stations.

Multiply this by the whole of the UK and then calculate the cost of converting these to 115V.

Technically I do not know what would be involved in stepping these transformers down to 115V from 240V. If a new transformer was required then the cost would be excessive.

The cost could be in the region of several £billion nationwide.

Then calculate the cost of replacing all the appliances (or purchasing step-up transformers)...

FOK :)

Loose rivets
6th Sep 2008, 17:30
Thanks for your feed back guys. Was just an idea and I now stand more informed of my original post.

Daz

Hee Hee.....I knew that wouldn't stop us.:}

FlyingOfficerKite
6th Sep 2008, 17:33
DazDaz

Well that's what PPruNe is all about - informed and unbiased comment!

Ladies and Gentlemen always here to help those with NFI! LOL

FOK :)

Keef
6th Sep 2008, 20:03
The other problem with lower voltage is that with twice the current (to maintain the same power at the end), the heat dissipation is quadrupled.
I squared R and all that. Your plugs and wires get a LOT hotter.

GOLF_BRAVO_ZULU
6th Sep 2008, 22:45
I still reckon my 24V FFR Rover truck is more efficient than the 12V farmer wagons. That said, I donít put my arm across the centre bulkhead anymore (the radio frame battery terminals give an unpleasant tingle) and replacement bits are nearly 4 times as expensive! Also, my headlights arenít quite so white as the 12V jobs. Ah, yes; less heat.

seacue
7th Sep 2008, 01:56
Pity the people in Southern Ontario who had 25 Hz mains power (115V) until after WW 2. Everything with a motor or transformer had to be special. Early generators at Niagara Falls were 25 Hz and are still used to run the abrasives factory from what I hear.

Ontario Hydro replaced every 25 Hz appliance for its customers when they changed to 60 Hz. The customers were overjoyed that they could now buy electrical goods from catalogs, just like everyone else.

[Some Canadian will doubtless point out errors in the above story.]

barit1
7th Sep 2008, 02:08
In most US cities, elevators ran on DC, and the power companies distributed DC where required.

In fact, Consolidated Edison stopped distributing DC in NYC quite recently (2 or 3 years ago). I guess any building with a DC elevator had to rectify their own power after that. :cool:

G-CPTN
7th Sep 2008, 02:20
I guess that DC was used for elevators otherwise they would oscillate up and down at 60 hz . . .

barit1
7th Sep 2008, 03:23
YyYyYyEeEeEeSsSsSs, IiIiIi GgUuUuEeEeSsSsSs SsSsOoOoOoOo!

Loose rivets
7th Sep 2008, 04:25
That's funny :}


Did I dream it, or has my post about B... Erm. the largest privately owned home in America been removed.

I was going to say that in this hyper-mansion, there remains the DC system in the basement. A wall is covered with a vast sheet of Ebonite with all the huge knife switches and other control thingies set into it. We were not allowed to go into the battery room for obvious reasons.

Mr Vanderbilt hedged his bets. A small town was built to support the mansion and its vineyards, and the A/C supply for the house was generated there. Noise? That may be the reason.

The house was built by men earning $1 per day. If they had a donkey, $2.

All that vast wealth, and the bloke dies of appendicitis not too many years later.

tony draper
7th Sep 2008, 08:07
Dunno if I ever told you chaps this but the first house in the world to be lit by electric ligh is but a stones throw from Draper Towers,the bloke who invented the electric light bulb lived there.
:rolleyes:

Brian Abraham
7th Sep 2008, 08:39
VOLTAGE Mr Drapes, VOLTAGE!!!!!! And was he AC or DC?

ORAC
7th Sep 2008, 10:57
It is why I always unplug things at night, to let any residual volts and amps fall out unseen while I sleep Back in the 50s/60s lots of houses were wired for electric by running the cable through the old gas pipes; you could buy screw in sockets to replace the gas mantles.

More to the point, I had an old aunt who went around making sure that something was plugged into each socket to stop the electric leaking out - she was hazy about the difference between the two systems.

Not many sockets in each room of course, in many there was only the ceiling gas/electric light socket. The most common adapter, therefore, was a plug in one for the light socket. I can still remember the cords hanging from the ceiling going towards the old valve radio on the sideboard.

http://www.74simon.co.uk/twoway2.jpg

seacue
7th Sep 2008, 11:49
ORAC,

One of my friends at university had earlier worked in the electrician shop at the US Capitol - that big building with the dome in Washington, DC.

That was before the extensive renovation around 1950 +/-.

Some of the wiring was still in the former gas pipes and some places the wires were just plastered into the wall. One could get a tingle if touching those walls in damp weather.

Loose rivets
7th Sep 2008, 17:41
I amp sure joule induce resistance to your reVolting idea by Faraday. Admittance to our reluctance to accept watt you diode to suggest could be rectified without impedance, unless your impermeability transforms. Wire you coulomb here with half bakelite, class B, zener, schottky ideas which hertz, you Planck?

Punmiester of the year? :ok:


I had a charming cottage in Austin, built same year as me, '39. There were cotton covered wires in the attic, the poles were kept about 10" apart. Ceramic bobbins allowed a turn or two of wire to support long lengths and corners. I assumed that it had been disconnected years ago. Bad mistake. :eek:

Folk used to peel back the cotton and solder (or sodder) another line in.

seacue
7th Sep 2008, 18:56
Mr Rivets,

I think you may be describing "knob and tube" wiring. My brother's house in Ohio still has a little of it.

http://en.wikipedia.org/wiki/Knob_and_tube_wiring

I've only seen the type which has stacked two-piece porcelain knobs nailed into rafters, etc. There was a ridged indentation to grasp the two wires either side of the nail. You apparently had the one-wire-support type. Porcelain tubes were used when a wire had to go through a rafter or wall.

seacue

tony draper
7th Sep 2008, 19:23
Bah! the electricity we had when I were a lad were much berra than this stuff we got now,and it were a lot cheaper.
:)

SpannerInTheWerks
7th Sep 2008, 19:58
Well it was newer then, like everything else it wears out! lol

What I can't understand is where all those electrons go?

You switch your TV on and by 'magic' electrons become photons and you watch a film.

Scientists say the light escapes into space - forever.

Now if I were to switch my TV on in a room without windows and neither the electrons nor the photons could escape, where would they go then?!

SITW :confused:

seacue
7th Sep 2008, 20:04
Now if I were to switch my TV on in a room without windows and neither the electrons nor the photons could escape, where would they go then?!

Heating the walls??

west lakes
7th Sep 2008, 20:04
Bounce around until you open the door, then they all make a rush for freedom:\

tony draper
7th Sep 2008, 21:28
"The" Electron doesn't go anywhere, there is only one in the entire Universe you know.
:)

hippotamus
7th Sep 2008, 21:29
Everyone knows that so called electrical devices actually run on magic smoke.

What do power stations produce --- smoke
connect a capictitor the wrong way and poof , the smoke escapes and the device doesn't work
too much smoke and the deice gets very hot , before the smoke escapes , thus ensuring the device no longer functions....

and that Ladies and gentleman was how I lost my job as a high school physics teacher :)

west lakes
7th Sep 2008, 21:51
Smoke
Which is why we now have a device to smell for the smoke trapped underground following a cable fault - works as well.


Spent 5 minutes once explaining the smoke theory to the company that we use to fix customer's appliances after certain types of faults, I don't think he quite got the theory

G-CPTN
7th Sep 2008, 21:57
When you switch off the light, do the photons continue to flow from the globe to the corners of the room, or do they return into the globe?
I've often pondered that, but never been quick enough to catch them and see . . .

Um... lifting...
8th Sep 2008, 08:14
One thought that TVs and light bulbs and so forth sucked in the darkness and needed to be changed out when they couldn't hold any more. Must revisit this theory for possible revision.

FlyingOfficerKite
8th Sep 2008, 12:56
Seacue

Yes heating seems to be the answer.

But, as a photon is a particle that acts like a wave (I think), I can imagine electromagnetic energy heating the wall, but where does the particle go? Is it absorbed by the wall (like a small bullet as its travelling at the speed of light) or does it transform the material of the wall, or is it transformed itself?

As there are several theories regarding photons, probably no one knows?

FOK :)

Blacksheep
8th Sep 2008, 13:31
Actually, to achieve some real economy, it would be wise to increase the AC generation/transmission frequency. That's why aircraft converted to 400 hz sixty years ago. This reduces the iron losses (see west lakes' post) and/or permits lighter iron cores. The only problem is any AC motors (A/C, refrigerator, washer, mixer...) would need redesign.Actually, aircraft used 400Hz right from the beginning of constant frequency generation. It had more to do with the practical size of the generators and the practical drive speeds resulting in eight pole machines driven at 6000 rpm.

There is another problem too. The inductive reactance of transmission cables limits practical transmission distance to about 150 metres. Beyond that, line losses (which vary with load) become unacceptable.

But don't try to convince a Kiwi A&C Chief Maintenance Engineer of such matters. Those guys know their Ohms Law... :}

barit1
8th Sep 2008, 15:58
Re transmission line losses at 400 hz:

Instead, think of the problem at 400 megahertz. There it's a case of impedance matching, tuning the source and load impedances so the VSWR is 1.0 ...

...and it's no different, in theory, at 400 hz. The practical considerations (size of tuning reactors) are a bit bigger, though. :}

Loose rivets
8th Sep 2008, 16:20
One is mindful of 2 pi f L old chap. Line inductance at 400 hz. we'd be heating the countryside.

Oi! I claim the copyright on this. :8


I can imagine electromagnetic energy heating the wall, but where does the particle go?

The photon would arrive at the wall and alight upon a convenient atom's electron cloud...probably. The lucky electron would be pumped up to a higher energy level. Then. The electron could, in a moment of contempt for the photon, spit it back out again, the photon being reborn at the speed of light. Possibly the energy might be combined with other like-minded atoms, and radiate out at infrared frequencies.

Now, here's the tricky on. The photon is a package of electromagnetic energy having zero rest mass. At what stage does a quanta of such energy, ie at what frequency below light, does an electromagnetic wave become contiguous? I mean...you wouldn't get a bloke on the BBC saying,

"There will now be a short intermission while we wait for the next quanta to convey your program to you."

Well, would you? Answers on a post card please.

G-CPTN
8th Sep 2008, 17:28
Current (!) house was built in 1901.
Next door remains unaltered, although no doubt the electrics have been updated at some time, however, the rear upstairs window is still equipped with a porcelain insulator, presumably where the electric supply entered. I don't know whether the house would be equipped from new.
http://i24.photobucket.com/albums/c19/GroupCaptain/IMGP0184.jpg

Blacksheep
9th Sep 2008, 13:11
There it's a case of impedance matching, tuning the source and load impedances so the VSWR is 1.0 ...I can imagine my Mum turning on the washing machine then disappearing into the cupboard under the stairs to re-tune her transmission line, carefully monitoring the VSWR meter as she does so. :ooh:

The mind boggles. :}

Wader2
9th Sep 2008, 13:53
More to the point, I had an old aunt who went around making sure that something was plugged into each socket to stop the electric leaking out -

One dark and stormy night in the Scotish Highlands Imade my daughters 7 and 9 make sure that there was a plug in every socket as we had hyrdo-electricty and we had to stop the water coming out. :}

Non-Driver
9th Sep 2008, 14:11
The significant advantage, according to the proponents, of 120v is the lerssened risk of electrocution. Doesn't always seem to work though and the belts hurt just the same here too.


I was always taught that its current that kills, not voltage ?

CATIII-NDB
9th Sep 2008, 14:12
Educational restbite - Re voltages & A/C Vis D.C - Its more complex than I thought - Do a Wiki on "War /Battle of the Currents" - Its a facinating story and provides some of the basis as to what this thread is all about.

and Yes you can transfer power over long distances using DC - Hummmmmmmmmmm.

CAT III

PS "so the VSWR is 1.0 ... " Is that the Voltage Standing Wave Ratio - ?

west lakes
9th Sep 2008, 14:27
Yes you can transfer power over long distances using DC


Hence the cross channel link is DC

http://http://en.wikipedia.org/wiki/HVDC_Cross-Channel

tony draper
9th Sep 2008, 14:38
Course yer can yer just make it alternate.:rolleyes:

G-CPTN
9th Sep 2008, 14:44
Since the first electric shock that I received from the wireless at my grandparents' house sixty years ago, I must have had a good dozen 'belters' yet I have survived.
Have I been lucky, or did that initial 'bite from the frog' condition me?

It's Not Working
9th Sep 2008, 15:05
To go ever so slightly off-topic how is the same frequency / phase maintained between suppliers.

I would image a number of suppliers within the UK all contribute to the National Grid. We import power from Norway (I believe) so therefore that has to be in-phase with the UK Grid. We import power from France, that too has to be in-phase with the UK. Norway is connected to Denmark, Denmark to Germany, Germany to France therefore presumably all those have to be in-phase with each other and so on across the European landmass.

Is there one master frequency/phase all have to comply with or is there a widget at each country's border that phases the power to whatever it is feeding? Clueless but would like to know.

CATIII-NDB
9th Sep 2008, 15:14
You are a repressed Physicist , everyone who has received the "Honour" of a belter and survived to tell the tale has that Spark of interest in EM theory - I'm sure that you will not ne Phased in any way by my comments and I suggest the "mathematically edited form" of Richard Fyneman's book" Quantium Electro Dynamics" as a start Great stuff. - Re earlier posts about Photons bouncing about when lights a switched off.

"Everyone knows Gas flames roar along pipes to our homes"

Knowledgeable CAT III.

CATIII-NDB
9th Sep 2008, 15:18
I worked for a Boss who was an Engineer at the National Grid. (computerised these days), Power plants had special circuitry to match the Phase & Voltage of the their output to the grid before they went on line - I think this might be the origional meaning of the phrase.

( PS See the roof of the Sistine Chapel -Re Sparks by one L Davinci )

CAT III.

west lakes
9th Sep 2008, 15:24
The declared frequency in the UK is 50Hz =/- 1%

So that is a fairly constant figure.
All generators connected to the grid are connected in parallel and synchronised with each other. In other words they are all at the exact same point in their rotation as each other.
To connect a single generator to a grid it is run up to speed and the output voltage matched to the voltage at the point of connection, it is then accelerated/slowed until it is at the point of synchronisation & then connected. In earlier days this was done manually using dials & lights, nowadays it is automatic. If connected slightly out of synch or without the voltages matching the "mass" of the system will serve to instantaneously accelerated/slow it and pull it into sync or match the voltages - usually breaking some expensive bits in the process and leading to one of those no tea, no biccy interviews

To then interconnect with another grid is, as you guessed, a major undertaking. As an example a good few years ago the synchronous tie between the north & south of the UK was lost following a number of faults, it took, if I recall, 6 weeks to re-establish it.

In the case of the HVDC link (see above) the problem does not exist, the French 50Hz Ac is rectified to DC, crosses the channel and is converted to 50Hz Ac in the UK, this is easily synchronised with the UK grid.

In larger continental grids I would guess that the maintaining of a synchronous tie is a prime requirement of their systems, and if lost a major undertaking, see UK example, to re-establish

west lakes
9th Sep 2008, 15:29
Once a generator is connected (at the time of connection they are not producing any current, only voltage) any further increase in input power cannot accelerate it any faster as then you would be trying to accelerate all the others connected.
So if the power input is increased the electrical power output at 50Hz increases.

It's Not Working
9th Sep 2008, 15:35
Synchronicity - what a lovely word!

In the case of the HVDC link (see above) the problem does not exist, the French 50Hz Ac is rectified to DC, crosses the channel and is converted to 50Hz Ac in the UK, this is easily synchronised with the UK grid.

Cunning!!

Thanks for your replies. It looks like the whole of the northern landmass has something in common, its power phase. Or are there countries out there that have declared UDI and don't import, export, share their power?

CATIII-NDB
9th Sep 2008, 15:40
At connection, if the generating set connections are open (Voltage only) are there complex issues of current & Phase at the instant of the generator going on load ?
I was thinking of the massive capacatance and Inductance of the generator winding coils Etc.


CAT III

west lakes
9th Sep 2008, 15:46
As far as I know most of europe is interconnected somewhere. North America the same - certainly bewtween Canada & the US which in itself has a national grid (of course the times it went wrong led to the North East US blackouts)

west lakes
9th Sep 2008, 15:50
CATIII
are there complex issues of current & Phase at the instant of the generator going on load ?

not experienced any problems with this, usually the voltage difference is slight and the aim is to try to synchronise at this point, a slightly higher voltage on the generator is not usually an issue as once connected the generator in this state will then produce current as voltage is then fixed.

Of course if the voltage of the generator is too high, it immediately runs the risk of producing too much current and becoming overloaded

Same result as earlier post

G-CPTN
9th Sep 2008, 15:57
the French 50Hz Ac is rectified to DC, crosses the channel and is converted to 50Hz Ac in the UKWhat are the % losses involved in that (over and above the transmission losses over distance)?

west lakes
9th Sep 2008, 16:00
G-CPTN, that I do not know

west lakes
9th Sep 2008, 16:03
It's Not Working

http://http://en.wikipedia.org/wiki/Union_for_the_Co-ordination_of_Transmission_of_Electricity

European grid member states

It's Not Working
9th Sep 2008, 16:23
West

Link didn't work but "Union_for_the_Co-ordination_of_Transmission_of_Electricity" into Wiki did. Many thanks for that pointer, lots of reading to do there.

The members and non-members look like a roll-call of the Eurovision Song Contest but I'll save that for a different thread.

Rgds

dazdaz
9th Sep 2008, 16:39
Bloody ell what have I started:eek:

CATIII-NDB
9th Sep 2008, 16:46
Thanks for your reply West Lakes - I have always wondered about the practicalities of large sets - I visited a 210 MW Generating Station at Nechells in my Home town when It was off load - school visit. - Still facinating - Control Room - Switching Yard (from a distance.) - I remember a switching Plug device that co-ordinated Phase / Voltage being shown. When the Generating Sets at Hams Hall in Warwickshire were decommissioned I went to the auction of getting one of the 33KV control room voltagedisplay sets expected £30.00 would do - I was disapointed. Hummmm.
CATIII.

tony draper
9th Sep 2008, 17:03
The older mains voltage CCTV cameras used to derive their sync pulses from the mains,fine if camera and monitor were off the same power distribution board, but on large installations with camera and control rooms miles apart we had to run two coaxials to each camera one for camera output and one for sync pulses from a central sync generator because they would go out of sync relying on the 50 hertz mains.
:)

dazdaz
9th Sep 2008, 17:40
Ok I'll play the game. So why has no one answered my previous query......Why does a rechargeable battery i.e.AA type have only a 1.2/1.3v. Whereas a non rechargeable battery is 1.5v:ok:

Daz:}

CATIII-NDB
9th Sep 2008, 18:07
Its to do with the internal chemistry of the battery - Wiki Battery University to find out more - No its not a legpull.

Cat III

tony draper
9th Sep 2008, 18:43
From what I recall a cell produced one volt, a 1 volt thingy was a cell not a battery,9 x 1 volt cells stuck together, ie a battery of cells,ergo one cannot have a 1 volt battery one can have a 9 volt battery of cells.
:)
I can remember taking our accumulator to the garage to be filled up wi lecky again,well one can remember accompanying one's Dad on these missions.
:rolleyes:

west lakes
9th Sep 2008, 20:19
I visited a 210 MW Generating Station at Nechells in my Home town when It was off load - school visit. - I remember visiting Fleetwood power station aged about 10 (openday) and then Preston a couple of years later, that got me interested in the industry.
Aged 16 the G.E.G.B. wern't taking on so joined the local Electricity Board as a Technical Staff Trainee - 35 years later I'm still doing the job I wanted aged 12.

tony draper
9th Sep 2008, 20:45
About time we had digital electricity,zeros and ones would travel for miles along wires wi no loss, then simply convert it back to 240 volts of proper lecky when it comes into yer house.
:)

CATIII-NDB
9th Sep 2008, 21:16
Dear Mr Draper - your binary electricity ( Hee, Hee ) has but one small drawback we are talking about the transfer of Power not info ie Product of Volts / Amps/ Phase not signals unfortunatley - but you have generated the idea of the transfer of power by Microwaves - phase coherent - would it work in say dry climates ? - acres of Solar Arrays in say Spain, transmitt the "mazer waves" to northern europe by say France then Euro super grid. I'm sure that the Pilots watching my efforts will have a lot to say on this idea.

CAT III.

Loose rivets
9th Sep 2008, 21:26
I think we aught to have two large masts here at the moment. One at ground potential and one at a bazillion volts.

When the hurricane comes here, the forces on the fairly conductive disc would be huge, and if not boil it away, would perhaps send it to Mexico where they cherish such phenomenon.

G-CPTN
9th Sep 2008, 21:31
Heard that Britain sells gas to the continent during the summer then buys it back (more expensively) in winter. We no longer have sufficient storage it seems.
Now it can't be too difficult to store electricity?
I mean we used to have electric storage heaters . . .

henry crun
9th Sep 2008, 23:33
dazdaz: While the voltage you mention is true of nicad batteries, other rechargeables have different voltages; a fully charged single Lipo cell will produce 4.2 volts.

barit1
18th Sep 2008, 13:28
Well - electrons are once again seeking the south pole after 82 hours of dormancy. I've been living with zero volts, but I'm baaaaack!

The barit1 household was assaulted by renegade remnants of Hurricane Ike, which passed through flyover country Sunday with 70kt+ surface winds, knocked down trees and signs and power lines, and left thousands of homes and businesses without power. Our local power company called in hundreds of workers from out of state to assist with restoration.

But living in the primitive manner for a few days isn't so terrible, if you have a roof over your head! ;)

tony draper
18th Sep 2008, 13:56
Put yer powerlines underground Mr B,one has oft commented that the USA looks a right mess wi all those poles and wires strung all over the place.
UG cables can't be blown down
:)

Loose rivets
18th Sep 2008, 18:11
I had no idea until I saw one of those wonderful late night programs, that the larger underground cables have to be oil cooled. What an undertaking. (groan)

BTW did you get that sound going? My driver arrived on SP 26289.exe

Dalex64
18th Sep 2008, 21:53
240VAC hurts twice as much as 120VAC.

arcniz
19th Sep 2008, 00:28
240VAC hurts twice as much as 120VAC.

But one feels it for a much shorter duration.

Lexif
19th Sep 2008, 10:11
G-CPTN,
Now it can't be too difficult to store electricity?Very difficult to store the energy needed on a national scale, the only viable solution seems to be pumped-storage hydroelectricity.
Pumped-storage hydroelectricity - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity)
It works by having to reservoirs at different heights, connected by tubes and pumps / generators. If you have more power than needed, you pump the water up, and on peak load times, you release the potential energy and run it down through turbines to generate electricity again. Efficiency: about 75%.

frostbite
19th Sep 2008, 13:11
At least AC bites and then throws you away.

DC bites and hangs on.

seacue
19th Sep 2008, 14:55
AC doesn't necessarily throw you away.

Very early in my career (ha!) I worked in a very old building. We had an antenna on the roof and our lab was two stories below. I unscrewed the connection from the coax cable from the antenna to a cable to the local apparatus. The difference in ground potential, clearly AC, made my hands contract so I couldn't let go. Fortunately someone yanked the cable out of my hand. May well have been a very close shave.

To this day I never grasp the uninsulated connectors on two cables when I'm about to joint them. I first make sure they are in electrical contact.

arcniz
19th Sep 2008, 18:49
I unscrewed the connection from the coax cable from the antenna to a cable to the local apparatus.

Must be part of the learning curve!

At a similar stage in life, while still in college, I worked night shift in a test lab for airbourne countermeasures systems. After unscrewing the waveguide joining screws for a transmitting tube on my bench, I methodically separated the tube from it's multi-kilowatt dummy load and then promptly flew fifteen feet or so across the room, making some odd noises in the process, observers said.

Don't know, in retrospect, if the real cause was having put self in series between source and load of a (very) hot rf circuit, or if the test stand had a faulty primary ground on the 150 kilovolts DC that made it all work, such that the waveguide I disconnected was also a de-facto ground path for the whole floating high-volts kaboodle. Perhaps a bit of both. Memory is fuzzy on some of the details.

Today such an incident would generate a mountain of paperwork and considerable fussing by medical folks. But those were much simpler times, and formalities were few on the night shift. Soon as they realised I was still alive, the other 5 or six young fellows in that group gave me a round of good-natured verbal abuse. Someone brought a cup of coffee and a couple aspirin from a gallon-size jar of tablets by the drinking water dispenser. After a short cooling-down period I set to finding parts to improve the interlocks on that test stand. Fortunately the tube, which was worth a few hundred times its weight in gold, later proved to have not been damaged by the variation in procedure. Was hard to make 'em, but they were sure tough.

Loose rivets
20th Sep 2008, 06:16
Told the story of my lecturer at PYE Cambridge leaving heal marks on the ceiling...he, among other told us to take measurments with one hand behind our backs.

To this day, I bellow at my lot if they put hand on electric stove and sink at the same time. (or any other similar pair.)

I came very close to losing my daughter cos a frayed iron lead on on of those springy lead tensioners. The fact that the iron was earthed did the harm.

We had to call a truce to some hi-jinks. One was zapping the local waitresses with a megga. A passion meter twas supposed to be. Made one of them cry...I didn't do it, one was a sprog then.

The other thing was, just as you got a meter probe very,very carefully into the innards of a turret-tuner, yer mate would explode a paper bag behind one. I explained to the lad why he was never to do that to me again.:*

tony draper
20th Sep 2008, 08:47
When you see six inches of a copper bus bar two inches wide by a half inch thick vaporised instantly yer realise just how much energy that lecrit has and how much it could harm a young lad.
:uhoh:

seacue
20th Sep 2008, 13:11
Twice in my life I have been present when a simple passive volt-ohm meter suffered an unexpected death. The first was when it was used to verify that a certain exposed metal was not connected to the 4 kV mains. But it was connected to the HV. We had neglected to use the HV probe. Similar failure to use the HV probe in the other occurrence - but caution had been used and the meter was hung inside the interlocked cage..

In both cases fire came out of all the holes and cracks in the meter case. Examination of the innards didn't immediately reveal any problems, the wires appeared to go the correct places - but then little balls of copper were noted down in the corner of the case. The copper had vaporized, leaving the insulation still routed correctly. The copper then condensed into the little balls.

In the first case we tripped the overloaded main circuit breakers and knocked the whole university off the power grid. Fortunately it was a Saturday and we had permission to be in the electric vault.

For a while I wondered whether my univ career would end midway through my freshman year.

RiscOS
20th Sep 2008, 15:14
It was 1960, I was 17.
I was working in a recording studio, loved the job, hated my boss with an intensity that I've never been able to rustle up for any other human being for the rest of my life. I should add the feeling was mutual.
New fangled tape recorder thingees in the shape of jolly green giants made by EMI had taken over and were about to be augmented by a couple of shiny new Ampex machines, but first the now obsolete huge old lathes that cut their wavy groovy tracks in acetate coated aluminium discs had to be removed to make room. The job fell to the boss and me.
When I came on shift the boss ( who worked office hours) had done some of the preliminary work and as soon as the they were disconnected from their leccy umbelicals we could swing them out from the wall and start removing internals to lighten them so they could be carried away.
Wally had armed himself with an enormous pair of sidecutters and has ready to do the dirty deed, but decided to first deliver a fifteen minute safety lecture in the dangers of cutting into mains wiring and the need to check, double check, triple check before applying the snip.
I listened attentively and offered to do a quadruple check just to be absolutely certain. He gave me a withering look that would have stopped a clock and curdled milk of magnesia and reminded me that he was a Supervising Technician and I was a technical trainee and he had already checked thoroughly. He took his sidecutters and went snip.......



:eek:BANG!!!:eek:



The blades and the hinge of the sidecutters vanished for ever leaving only the handles.
Wally went white, and retired to his office.
He had pulled the plugs that powered the jolly green giants, but the lathes were not powered by yer poncy 230 volts from a 3 pin plug with phase, neutral and earth, they were hard wired ter yer real meaty 400 volts three phase man-eating leccies.


Listen You Bl00dy stupid spelling checker ALUMINIUM is the correct spelling.

dazdaz
20th Sep 2008, 15:40
Remember the S.I.D.E. rule..Switch off. Isolate. Dump. Earth.

Having said that may I slightly drift this thread to a question of gas. Why does a central heating boiler require a flue to the outside (obviously to remove carbon monoxide) while as gas cooker, say with all rings/oven and grill burning does not? The gas cooker surely must be giving off more carbon monoxide with all burners alight than a boiler.

Daz

Loose rivets
20th Sep 2008, 18:21
Yes, I've oft wondered that. You'd think at Christmas etc., when cooking can go on for hours with windows closed against the winter, that the noxious gasses would certainly be dodgy.


There there was the old man, dead beside his gas fire.

It was a modernish terraced house, and friends purchased it and turned it into the prettiest cottage you could put in a modern shell. They found the vent in the floor had been covered over with tin. Oh, well, perhaps the old boy didn't like droughts. When they came to have the chimney lined, the guy found a sweep's brush jammed up the flu. Things stacked against that old boy.

G-CPTN
20th Sep 2008, 18:28
Isn't it a question of percentage of air supplied and consumed?
A flame that burns lean produces carbon monoxide, whereas burning rich produces carbon dioxide - or is it vice-versa?
Of course, carbon dioxide does not support life (ie breathing) so a build-up of CO2 can suffocate anyone confined to such an atmosphere.

acbus1
20th Sep 2008, 18:30
125v is cheaper than 240v because it uses less ink.


Oh, well, perhaps the old boy didn't like droughts. When they came to have the chimney lined, the guy found a sweep's brush jammed up the flu.

Droughts make me Thursday.

Flu jams up my nose.



Get a dick shone Harry, fer fecks sake, Mr Loose.

tony draper
20th Sep 2008, 18:46
I understand North Sea Electricity is not lethal.:cool:

Pontius Navigator
20th Sep 2008, 20:46
I understand North Sea Electricity is not lethal.:cool:

Wrong. Water conducts the electricity so you can become electrocuted without touching the wires.

Pontius Navigator
20th Sep 2008, 20:50
Looking up the last few posts:

I have an insulated handled screw driver with a burn mark on the shaft. The 30 amp fuse of the electric storage radiator had indeed fused but the live terminal was still live.

'nother occasion, a few wiggly amps arrived from God and took a short cut to earth, through an earthing lead. The lead was pure rubber afterwards, the copper core had been blown.

Keef
20th Sep 2008, 22:35
I have a very nice 18-inch long screwdriver with a half-inch diameter shaft, excellent for removing screws that don't want to see things my way. There are two deep notches in it, where the metal was melted when I shoved it across the pins of the reservoir capacitor of my switched-off linear amplifier power supply (rated at 2.5kV at 1 amp) - just to be sure.

That has to be the loudest BANG I ever heard.

There was one of those large green ceramic tubular resistors (100k) across the output of the power supply, but old age and heat had got to it. 'Tis a beautiful 32uF 5kV working block paper cap, 18 inches by 9 inches by 6 inches and v v heavy - made for the army, I would think. Origin unknown. Still have it, 40-odd years later.

I'm glad I checked before reaching for the top cap on the PA valve.

frostbite
20th Sep 2008, 22:38
You might have discovered your own resonant frequency had you not!

seacue
21st Sep 2008, 00:23
Some of the late 1950s coherent US radars had BIG klystron amplifier tubes, often made by Eimac. The accelerating potential was 105 kilovolts - yes, over one hundred kilovolts. Probably at around one ampere.

One may not realize it, but many capacitors are "sticky" and retain a charge hidden away inside. For safety, one must keep a short across these high voltage capacitors when not in the circuit. But one day the short was forgotten or defective or ... The capacitors sat all night unshorted. The next morning the main designer of the capacitors got across the terminals and ZAP - one fewer capacitor designer. Sad when someone who knew the dangers succumbed to them.

Bushfiva
21st Sep 2008, 01:06
many capacitors are "sticky"

And, in the right circumstances, self-charging. I worked in an HV lab where all the components were the size of an arm, leg or person, and got winched into place. To make measurement easier for gravity-bound mortals, the ceiling was the ground plane. So the circuits were built upside-down. Basically the more likely something would be capable of zapping you, the closer it would be anyway. Apparently dead components stacked around the room could self-charge as the day wore on.

There was a box of flourescent tubes at the entrance. The warning notice at the entrance said something like

- No entry without a flourescent tube.
- If the tube glows, go somewhere else.
- Touch nothing unless someone else has touched it before you.

I hated the place. One of the bits ate my spanner once.

Gargleblaster
21st Sep 2008, 01:34
I installed a 132 KV facility with some fantastic Siemens guys back in the 80ies. Was in the middle of the city, so all was in-house, and pressurised with methinks argon (The arc-over distance in free air is 1.32 metres, remember there's 3 phases, you quickly spend an acre, hectar or similar on such facilities unless enclosed). Anyhow, me alone in said 200 square metre facility, underneath the main switch (big blue tank). BANG ! Someone at HQ had done a test on/off. Milliseconds later: Bang : My head hitting the damn tank.

Anyhow, mostly worked with 11KV facilities, which were dangerous enough. Worked with one guy who couldn't use his hands much, a switch had blow up on him. Our most loaded facility was doing 1200 Amperes (at 11 000 volts !), the whole place hummed and vibrated, and so did anything made of metal. I was naive enough to go to work with my 80ies Casio digital watch, which got fried. The "bus" was made of 10 by 50 mm copper bars, and they still got warm.

Loose rivets
21st Sep 2008, 01:57
Get a dick shone Harry, fer fecks sake, Mr Loose.

Why, and deprive everyone of 'avin' a larf at me spellin' ?

Without a spell checker, I may as well be writing in Hebrew.

I was an advanced reader until some shit of a teacher beat me nearly senseless one day. I was eight years old. It could have been coincidence, but somehow I doubt it. After that, working with electrickery and being a pilot was about all I could do for a job :}