The Genius of Invention

Yes, nice to see some real hardware.

I didn't know that James Watt came to the subject by having a model of a Newcomen engine to mend.

And the models and the oil drum experiment weren't bad.

Reply to
newshound
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I experimented with two days fasting a week for 3 weeks

When I say fasting, I mean total fasting - nothing but water. I found no overall net loss

I'll give it another less extreme and longer test in due course

Reply to
geoff

Definition of a bimbo.

Reply to
harry

The whole program seemed to be based on the premise of everything being "so big!"

Reply to
Apellation Controlee

They did at least credit light bulbs to "Swan & Edison" rather than just "Edison"

Reply to
Andy Burns

I got tired of being told that the alternator has to spin at 3000 rpm. That only needs to be said once.

The models and demos had been done better in the past by Adam Hart-Davis and Jim Al-Khalili.

Reply to
Steve Firth

Did they even mention the direct link with 50Hz mains frequency? Maybe I missed it. 3000 rpm was indeed mentioned several times.

Reply to
Reentrant

No, they mentioned that 3000rpm is 50rps but didn't bother to mention the link to mains frequency. No mention of three phases either. And why stop Discussion of steam engines with Watt? Why no mention of triple expansion engines linking that to turbines?

In short very little information thinly smeared over an hour, because BBC producers think everyone is as thick as they are.

Reply to
Steve Firth

It's going to cause some confusion if they sell the programme to the Americans, that's for sure. Their generators turn at 3600 rpm.

Discussion of triple expansion steam engines may come in the next programme, which is allegedly going to cover the application of high pressure steam (As against atmospheric) engines and internal combustion to transport.

As for the generator having to spin at 3000 rpm, they don't have to. Four pole ones spin at 1500 rpm, and if you're using a reciprocating engine using internal or external combustion, then eight pole generators turning at 750 rpm make a lot of sense.

Reply to
John Williamson

actually generators are three pole 6 pole 9 pole etc..

They generate 3 phase.

Reply to
The Natural Philosopher

I still don;t understand why only calories are counted. if that's all that is required then I have todays meals 'sorted' I have a 16 multi-pak bag of crips, 133Cal per bag that's 2128 just enough left over for a pint or two or three.... of beer.

Reply to
whisky-dave

I'd like to see how you get an odd number of poles, given that there are always two poles in a magnetic field. It's possible my terminology is out of date, I was taught 2 poles, 4 poles, etc., as that was the number of magnetic poles in the system, so maybe 6, 12, 18, and so on for 3 phase if you're counting the connections, but there is still only one magnet, giving two magnetic poles on a 3000 rpm, 50 Hz 3 phase generator. If you add another pair of poles, AKA magnet, making it 4 pole, then the generator will work at 1500 rpm, and so on.

Reply to
John Williamson

That would be pole pairs?

Reply to
Tim Lamb

I think the assumption is that the majority of people eat "reasonably" sensibly.

When the results are analysis, the ones that don't will be the percentage who don't benefit

tim

Reply to
tim.....

I would go along with you. In the case of an alternator where you are inducing current in the stator, the thing which matters is the number of poles on the rotor. Two poles (one pair) rotating at 3000 rpm produces 50 Hz.

Chris

Reply to
Chris J Dixon

No. Poles.

3 poles and two magnets will give you three phase. you can to an extent double up the magnets to double the frequency.

Our double up the poles.

Reply to
The Natural Philosopher

'pole' generally refers to the actual windings..

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Reply to
The Natural Philosopher

I was rather thinking wound rotor but I suspect each magnet will have two poles.

This is progressing to a Rod S argument:-)

Reply to
Tim Lamb

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A nice wiring diagram showing what I would call a 2 pole,3 phase generator, with rectifier and control gear, as used in most cars and other vehicle systems. Depending on the layout of the windings in the rotor, it may be a 4 pole machine, though.

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$file/technical_note_comparison_of_4pole_and_2pole_designs_for_large_motors_and_generators_en_052011.pdf"A 2-pole generator (My insert: At 3000 rpm for a 50 Hz supply) is often used because this avoids the need for a gearbox, but in many cases a

4-pole generator with gearbox would have a lower investment cost and provide a better utilization factor. For systems running at 3600 rpm, 2-pole generators are the favored option because gearboxes are not needed. Above or below 3000/3600 rpm, 4-pole generators are the preferred option." A 4 pole generator (And motor) runs at 1500 rpm shaft speed.

This is for stuff over 7 megawatts, so presumably it's all 3 phase at somewhat more than 415V between phases.

They make 'em, they should know. :-)

Reply to
John Williamson

Not any I've built.

Those ones, too.

Reply to
Grimly Curmudgeon

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