Please explain yourself.
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16 years ago
Is a dimmer and incandescent light efficient?
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16 years ago
It all seems very basic stuff to me. What bit(s) don't you understand?
Ian
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16 years ago
Far more than you, by the look of your contributions to this thread.
No one who knew what they were doing would apply your arguments to the type of circuits as you do. That is unless they are trying to appear clever.
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16 years ago
,
Really? Why not? The RMS value of a signal over a particular period is just the square ROOT of the MEAN of the SQUARE of the value under consideration. Or:
RMS(f(t)) = sqrt( integral( lowBound := t1, highBound := t2, func := f(t)**2 ) / (t2-t1) )
(and that would look a whole lot prettier it I wasn't constrained to ASCII!)
If the signal is periodic (and one is not trying to be deceptive), then t1 and t2 should be corresponding points in the period.
If the signal is not periodic, then the one is usually interested in the limit as the interval tends to practically infinity.
In the case of the torch, the RMS voltage, RMS current, and RMS power over a week will all be practically zero. However the power factor will be very close to one.
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16 years ago
And what arguments do you think I am trying to apply to what circuits?
You may care to remember that I am responding to the claim that "power factor" may always be usefully defined as "power dissipated / Vrms Irms" ...
Ian
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16 years ago
Indeed. Nice to see that someone sees what I'm getting at.
Ian
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16 years ago
I do remember, but I've also noticed you've neevr said what definition you use for power factor. You only seem to throw other points back at people. I thought this site is a DIY one and I assume the people using it want advice not academic points that bear no application to the questions asked. Not a very good way of communicating and spreading knowledge and experience.
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16 years ago
It's called Socratic questioning, dear boy.
The claim was made, repeatedly, that a dimmer controlled light has a lagging power factor because the load current doesn't start to rise until some time (
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16 years ago
Oh dear. Yiou have really shown your ignorance now. And still not defined what your quantities relate to.
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16 years ago
I haven't a clue what you're talking about now. Haven't defined how what quantities relate to what?
Why don't we go back to the beginning?
What do you think the power factor is for a resistive load (let's leave out non-linearity for now) supplied by a dimmer?
There is, you know, a distinct chance that we're actually on the the same side here!
Ian
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16 years ago
The term power factor is not applicable to non linear devices.
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16 years ago
Opps!
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16 years ago
Excellent, personal abuse, do keep it up.
Can't think who you might mean, but anyway I was out of the country at a conference.
However it's been self evident to me since I was seven that a cycle front lamp (Cycle front lamp eh? Showing my age there) gives much less than half it's light output when the battery is down to half voltage.
Piss-poor try.
DG
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16 years ago
On Sun, 16 Mar 2008 23:47:07 +0000 someone who may be Derek Geldard wrote this:-
Nice try. However, readers will observe that my comment does not refer to any individual. Therefore it cannot be personal, unless one tries to twist it.
It does partly depend on the type of cell. However, light output becomes close to zero long before zero voltage is reached. A cycle lamp with a "traditional" bulb will put out just a little glow when the 1.2V rechargeable cells reach around 0.9V. Much the same with "non-rechargeable" cells.
Next contestant please.