My latest whinge...

On Sat, 13 May 2006 19:53:32 +1000, Treadly wrote:

I think for single phase it's sqrt 2 and for three phase it's sqrt 3.

Actually sorry. I've got the wrong end of the stick and misinterpreted
Tim's post. I still think it's wrong, but it's curiously close to right.

240 * sqrt(2) is 350, which is the old peak variation. The official values
are now 325 and 230 respectively, but there's a 10% variation allowed, so
240 is still pretty common.

240 is the integral of 350 sin x.

What we're after is the integral of 350 (sin x - sin (x-120)), which
basically gives you an out of phase sine wave with a peak amplitude of
around 600V. 600 / sqrt (2) is 415 V. Those values should now be peak 560
and RMS 400.

Off the top of my head I suspect the sqrt(3) value is simply a
coincidence. I'd have to dig up some very well buried calculus memories to
say for sure.

--
Dave Hughes |
"Hey, watch the 'fro" - Danny Glaze

TimC wrote:

On 2006-05-13, Vincent Patrick (aka Bruce):
* Bicycle technical types. The idea of extracting a crank scares me, but
I like to learn from their mechanical knowledge. Now I know that a chain
whip is not some kinky perversion.

But it can be, baybe!

Yeah, whatever. I just didn't want to start a whole thread on personal
chain whips.

* Political types. Without wanting to upset people, riding my bicycle
has nothing to do with voting Labor
^^^^^ Be careful with that axe, Eugene.
We don't vote Labor around here, and we don't like the types that do
Haven't you heard? We're all communists!

What a relief. So that rumour that you're a part-time researcher for the H.
R. Nicholls Society is completely untrue?

* There's another class of "competitors", too: cyclists who enjoy
competing against themselves and noticing their gradual increase in
strength or
speed. It's not my main reason for cycling, but I plead guilty to
enjoying
going a little faster than I could before. Not always: sometimes my
commute is a slow slog into a headwind, and sometimes I just enjoy
freewheeling along at a leisurely pace. Speed is not just to be enjoyed
by competitive athletes. There is a point well before any feeling of
athletic
exertion when you can enjoy a bicycle's speed. As a young boy I liked
to 'race along' by myself on my single speed bike. Certainly, it is not
the same as "smelling the roses", but it is still enjoying the special
nature of cycling.

And admit it. Flying down a hill faster than the speed limit is kinda
exhilarating.

Yep, I admit it - traffic speeds under human power is a nice feeling. I've
only ever broken the speed limit on a bike a couple of times, and one of
the times it was more scary than exhilarating.

One of my life goals is to get caught by a radar trap while cycling. I
would treasure the infringement notice.

Cheers,

Vince

Vincent Patrick wrote:
Yep, I admit it - traffic speeds under human power is a nice feeling. I've
only ever broken the speed limit on a bike a couple of times, and one of
the times it was more scary than exhilarating.

Meh, I do this daily. Local primary school zone is 40km/h. At the
bottom of a hill.

--
..dt

Zebee Johnstone wrote:

I am competitive in that I can't help measuring myself against others.
I haven't been able to stop doing that, so you can imagine my blood
pressure

Does this mean we have to let you 'win' all the arguments here? :-)

At least you can relax in the knowledge that cycling reduces your blood
pressure.

Cheers,

Vince

In aus.bicycle on Sat, 13 May 2006 21:31:56 +0800
Vincent Patrick wrote:
Zebee Johnstone wrote:

I am competitive in that I can't help measuring myself against others.
I haven't been able to stop doing that, so you can imagine my blood
pressure

Does this mean we have to let you 'win' all the arguments here? :-)

Of course! It's the least you can do. Besides riding very slowly if
you see me coming.

At least you can relax in the knowledge that cycling reduces your blood
pressure.

if not your heart rate....

Zebee

Stuart Lamble Wrote:
On 2006-05-13, Resound sacredchao@ wrote:
[three phase power]
Ah, so there's four separate cables then.

Yup. Next time you see one of those transmission lines, look closely
at
it. You'll see that there are a couple (anywhere from 1 to 4, in my
experience) of very thin cables at the top, and a great many more
thicker cables below. The thicker cables carry the phases; the thin
cables are the neutral return.

--
My Usenet From: address now expires after two weeks. If you email me,
and
the mail bounces, try changing the bit before the "@" to "usenet".Talking to a Liney, he says the usual practice is the one closest to the
road is neutral then the phases are red white and blue.


--
Treadly

On Sun, 14 May 2006 04:23:57 +1000, Geebs wrote:

Sqrt(3) is definitely the correct value, you don't need to work out any
integrals.

Oh boo, where's the fun then?

if you have 3 equal length vectors (phasors in the electrical
world) each radiating from a common point spaced at 120 degrees then all
you need is some basic trigonometry to calculate the distance between
the ends of any two of the adjacent phasors and the the answer is
sqrt(3) x the phasor length (ie 240 x 1.732 = 415).

Fair enough. That makes sense. But why do something the easy way when you
can be all geeky?

--
Dave Hughes |
Flagrant system error! The system is down. I dunno what you did,
moron, but you sure screwed everything up - Strongbad

deejbah wrote:

Terry Collins Wrote:
deejbah wrote:

You can also have a problem where if the person is just above the
level
they are teaching, that people do not pay attention or do not
respect
the instruction given as it is perceived that they do not know
enough
to be instructing someone else. A misguided perception, perhaps, but
a
common one in my experience.

No argument there. Some people have to learn somethings the hard way.
{:-).Then there are the gender issues. I am never failed to be amazed by how
many guys fail to progress in their sport because they will not listen
to what a female coach or slightly more experienced player/competitor
has to say.

I did have a young man walk out on my intro session to boxing, saying he
came along to fight, not for a "fscking boxercise class"

Which was very entertaining when he came crawling back two weeks later,
tail between his legs, because his mates had stayed behind and been
impressed. Of course by then they were all off being supervised by the
head coach and he was there without his mates' support! (Ah, but at
least he came back.)

Tam

Zebee Johnstone wrote:

In aus.bicycle on Fri, 12 May 2006 16:48:55 +1000
deejbah wrote:
No argument there. Some people have to learn somethings the hard way.
{:-).Then there are the gender issues. I am never failed to be amazed by how
many guys fail to progress in their sport because they will not listen
to what a female coach or slightly more experienced player/competitor
has to say.

Or women who don't progress because the male coaches don't comprehend
women's body type or way of thinking.

I walked in to boxing and met a coach who said, "You will be good at
this sport, not despite the fact that you are a woman, but because of
it."

Wow. His philosophy was that, having no preconceived notion of how
boxing should be, I would be open and willing to learn, and easy to
teach. So try beating that one.

Vincent Patrick wrote:

Tamyka Bell wrote:

Vincent Patrick wrote:

Tamyka Bell wrote:

Exactly - students are expected to pay back HECS debts, and even
students on PhD scholarships will as postdocs contribute tax (in a
higher bracket than from their undergrad degree) - oh except that with
no incentive to keep scientists in Australia, most head overseas...

PhDs in a higher tax bracket? You obviously don't mean the PhD scientist
I
employed who previously had a job stacking comics. :-(

Well, at least he had a job. His basic science degree would've got him
the dole.

Tam

I think his non-PhD mates had gotten jobs years before.

But were they employed as scientists?
Or were they employed as consultants and in generalist APS roles?

Mostly they are deluded fools, those who do PhDs for the money. Oops. :-)

agreed. There is no money in science in Australia. For your wages or
for your research. Thus those who do it for the science end up overseas.

T