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[tonyappuk]

Nothing is as simple as the tree-huggers would have us believe!
Tony

[sevenlayermuddle]

BTW - 'lest I was misunderstood, I wasn't suggesting that anybody trying to save energy is a tree-hugger, I always take energy-usage (including) standby into account when choosing new appliances, and I'm becoming a proper scrooge in my old age, rushing around the house switch off the lights and other stuff at every opportunity.

 

[scottiesmum]

I leave everything on standby  ...... makes a lovely 'fairylight' walkway throughout the house    .....  very useful in the pitch black of night when all the shutters are shut   8)

[tonyappuk]

Nothing wrong with trying to save money. It's being exhorted to save the planet that annoys. I'm with Scottiesmum.
Tony

[guest]

Something that's worth bearing in mind is that 40% of the electricity "used" in the UK is lost in transmission - ie its power losses in the high-voltage cables which connect the power stations to the users of the electricity. Gas on the other hand has no transmission losses, however its a fossil fuel source rather than a renewable source.

There's no easy answers but I wouldn't bother worrying about it as govt & businesses need to get their "houses" in order to make a difference.

The long-suffering, persecuted, ripped-off consumer doesn't actually consume enough power at home for any of this energy-saving nonsense to make a difference - apart from in your pocket of course.

[sevenlayermuddle]

One thing that'll make a difference fairly soon is the EU-inflicted ban on old-fashioned light bulbs.  As of 2010 (start- or end-, I don't know), if I've got it right,  we'll no longer be able to choose between low-energy and incandsescent?

Personally I use a mixture of low-energy and incandescents as, IMHO, both have their place. But old-fashioned bulbs are already getting harder to find, and I've already started stock-piling.  In fact I've been down to B&Q on such a mission at lunchtime - I needed only one 25W 'mini globe' to match the others in a dimmable multiple-fitting, but I bought six instead of one, just in case they've dissapeared from sale next time one blows. 

Thought: If I stockpile enough of them, and I decide upon a life of crime, maybe I'll make my fortune from a future black-market for 'proper light bulbs'? 

[Imagine.]

Something that's worth bearing in mind is that 40% of the electricity "used" in the UK is lost in transmission - ie its power losses in the high-voltage cables which connect the power stations to the users of the electricity.

True. I think the national grid carries about 240,000v - 450,000v which along the way is toned down using a series of "step-down" transformers I think most of the energ loss along the line is due to electromagnets in the nearby vicinity but I could be wrong.

[sevenlayermuddle]

I think the national grid carries about 240,000v - 450,000v which along the way is toned down using a series of "step-down" transformers I think most of the energ loss along the line is due to electromagnets in the nearby vicinity but I could be wrong.

The reason for the high voltages is that the power loss along the lines (disregarding any transformer losses) is the product of the line's total resistance and the square of the current passing through it.  The current flow is inversely proportional to the distribution voltage, so a high voltage means a low current and because the power loss is proportional to the square of the current, a much, much, lower power loss.  But although the power loss is, in my words, 'much much lower', it's by no means zero.

There once was a time when I'd have known whether the resistive loss was more significant than the transformer losses but that was 30 years ago and, these days, I've trouble enough remembering what happened yesterday.  In any event, if they used low voltages over long distances, the resistive loss would be phenomenal.

[roseway]

There's no loss due to nearby electromagnets, but there is electromagnetic loss (iron loss) in the transformers, so that's probably what Imagine was thinking of.

[sevenlayermuddle]

If we accept Rizla's figure of 40% loss (and I've no reason to doubt it), then that would mean that a relatively small number of transformers were each dissipating almost as much heat as the sum total of the  much larger number of consumers that they supply.   My guess is that the heat dissipation from such transfomers would be unmanageable.  But I may be missing something (or just plain wrong).

And, as Imagine pointed out, there'll be a progressive series of transformers so the heat loss would be spread around between them.  Still, they'd be a popular place for the local cats to snooze.

[Imagine.]

SevenLM I think you work out the electrical resistance by R = V divided by I or Resistance = Volts by Amps so I lets say 450,000v so if my on going education works there should be 45,000amperes ? so assuming i'm right Resistance = 450,000v by 45,000amperes that would be 10 "ohms" . Plus there would be other sources of interference as on a phone line like weather. Hooray for education 

[Yorkie]

My head hurts now.

Going slightly off at a tangent, as some of you may know I have a whacking great pylon at the bottom of my garden, sometimes it sings, especially in the damp foggy weather we've just had lately, but not when its raining anyone know why. I understand why it crackles when we have a lightning storm overhead (I think) but not why it hums (no I don't recognise the tune) in certain weather conditions.

[oldfogy]

V = Volts, A = Amps, R = Resistance (ohms) W = Watts
Providing you know any 2 of the above values, it is then possible to find the value of any other value.

  V ................ W
----- ............ -----
A x R ........... V x A

Use either formulae to find:

Volts = Amps x Resistance
Volts = Watts divided by Amps

Amps = Volts divided by Resistance
Amps = Watts divided by Volts

Resistance = Volts divided by Amps
Watts = Volts x Amps

****************
edit:
Correction and addition to formula's

[Imagine.]

My head hurts now.

Going slightly off at a tangent, as some of you may know I have a whacking great pylon at the bottom of my garden, sometimes it sings, especially in the damp foggy weather we've just had lately, but not when its raining anyone know why. I understand why it crackles when we have a lightning storm overhead (I think) but not why it hums (no I don't recognise the tune) in certain weather conditions.

The humming could be tiny amounts of electromagnetic activity. Its pretty normal for pylons to hum but is it during sunny days or just rain. and OF thanks for that I thought it was Resistance = Volts divided by amps 

[sevenlayermuddle]

The equations are as follows:

1) Power = V x I.
So, if at some moment in time a town requires 1 Million Watts to run it's TV sets and street lights, you can choose to supply it with 1,000,000 Volts at 1A, or 1V at 1,000,000Amps, or more usefully, some compromise like 250V at 4,000 amps.

2) The voltage drop across a resistor is I x R.
3) Combining (1) and (2) the power dissipated by a resister is I x (I x R)., or I squared R.

If you look upon the power line as a big resistor, then you can see from (3) that the power loss is proportional to the square of current.  Yet, as in (1) you can freely choose either volts or amps, at no extra cost to the generator, allowing you to vastly reduce the power-loss just by tilting the voltage/current balance towards volts rather than amps.

I remember, as a youth, being quite impressed and excited by this method of, to my simple mind, apparently tricking the laws of nature.  I got even more excited when as a student I learned that complex number theory could be used to explain what happens inside inductors and capacitors which, thus making a useless mathematical impossibility (square root of -1) suddenly very useful.  Ah, these were the days.  I wish I could get so easily enthused nowadays.  I wish I could even remember what the heck complex numbers are

- 7LM