Observations on a UPS - follow up to a previous post

Agreed. However there is a newer kid on the block, and that's the power
factor corrected SMPS. This technology has been reduced to an IC, and it
shows up in items as humble as compact flourescent light bulbs. If the
power factor is 1.00 or approaches it, then the current and voltage are
largely in-phase.

I checked some excellent CFLs from Home Despot (instant turn-on, excellent
color balance) with the Kil-a-Watt. It showed a power factor around 65%,
which struck me as rather low. Such a low PF also partly offsets the
money-saving advantages of fluorescent lamps.

Opinions, anyone?

David wrote:

.... snip ...

This all started with a discussion of the Kill-A-Watt meter which
measures RMS voltage, RMS current, and Watts. Maybe the following
will clear some of the confusion.
The computation of RMS was described in an earlier post. The
product of RMS voltage and RMS current is Volt-Amps. Power, and
therefore power consumption (Watts=power/second), is computed by
the integration of the product of instantaneous volts and amps
over time. The power factor then becomes Watts/Volt-Amps. The
accuracy of the wattage and RMS calculations with voltage or
current waveforms that change rapidly is related to the sampling
rate used in the integration. Any wave shape for either voltage
or current will produce mathematically meaningful RMS and power
measurements. I am sure someone will point out any mistakes I have
made here.

You omitted that a periodicity is required. An infinite wavelength
is also allowable. :-)

BTW, please do not remove attributions for material you quote.

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
http://cbfalconer.home.att.net



--
Posted via a free Usenet account from http://www.teranews.com

William Sommerwerck wrote:
Agreed. However there is a newer kid on the block, and that's the power
factor corrected SMPS. This technology has been reduced to an IC, and it
shows up in items as humble as compact flourescent light bulbs. If the
power factor is 1.00 or approaches it, then the current and voltage are
largely in-phase.

I checked some excellent CFLs from Home Despot (instant turn-on, excellent
color balance) with the Kil-a-Watt. It showed a power factor around 65%,
which struck me as rather low. Such a low PF also partly offsets the
money-saving advantages of fluorescent lamps.

Opinions, anyone?

Well, your computer switcher probably has a power factor of about 1.2 to
1.5... so run a couple computers and the lead and lag will cancel one
another out...
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"William Sommerwerck" wrote in message
. ..

Agreed. However there is a newer kid on the block, and that's the power
factor corrected SMPS. This technology has been reduced to an IC, and it
shows up in items as humble as compact flourescent light bulbs. If the
power factor is 1.00 or approaches it, then the current and voltage are
largely in-phase.

I checked some excellent CFLs from Home Despot (instant turn-on, excellent
color balance) with the Kil-a-Watt. It showed a power factor around 65%,
which struck me as rather low. Such a low PF also partly offsets the
money-saving advantages of fluorescent lamps.

Opinions, anyone?

The dimmable CFLs I get from eBay (love those California lawmakers!) have PF
speced 0.90. I haven't got around to testing one, though.

On 8/14/2007, CBFalconer posted this:
Arfa Daily wrote:
"CBFalconer" wrote in message
Arfa Daily wrote:

... snip ...

OK. I'm not sure that 'RMS' is the right term to attach to any
value derived from a ragged-arsed waveform, as it is a mathematical
function normally associated with symetrical waveforms, which the
draw by a SMPS may very well not be, but I see what you're saying.

What I am trying to say is that a chip which is designed to produce
an RMS reading from a sine wave, may well produce a meaningful
figure from a non-sinusoidal waveform also, but *only* if it is
still symetrical.

Oh? Try a square wave, for example. Nice and symetrical. You are
over-simplifying.

Explain ?

The integral is peak voltage times current. Simple. Not 0.7 *
peak voltage.

No, the integral is instantaneous voltage squared. Simple.

Current is also constant for resistive loads, not
proportional to voltage. RMS doesn't work.

You are contradicting Ohm's law, e = ir, which can be rearranged to
read i = e/r. Current is precisely proportional to voltage for
resistive loads. Simple.

I've used small letters to follow an old convention (is it still used?)
that lower-case letters represent varying values and upper-case letters
represent constant values (such as in analyzing DC circuits).

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
http://cbfalconer.home.att.net

--
Gene E. Bloch (Gino)
letters617blochg3251
(replace the numbers by "at" and "dotcom")

On 8/15/2007, William Sommerwerck posted this:
Agreed. However there is a newer kid on the block, and that's the power
factor corrected SMPS. This technology has been reduced to an IC, and it
shows up in items as humble as compact flourescent light bulbs. If the
power factor is 1.00 or approaches it, then the current and voltage are
largely in-phase.

I checked some excellent CFLs from Home Despot (instant turn-on, excellent
color balance) with the Kil-a-Watt. It showed a power factor around 65%,
which struck me as rather low. Such a low PF also partly offsets the
money-saving advantages of fluorescent lamps.

Opinions, anyone?

Great minds: I also call it Home Despot...

--
Gene E. Bloch (Gino)
letters617blochg3251
(replace the numbers by "at" and "dotcom")

The dimmable CFLs I get from eBay (love those California lawmakers!)
have PF speced 0.90. I haven't got around to testing one, though.

What brand?

I bought a dimmable GE two years ago, and it worked. You get only about 10
steps, at the top of the X-10's 256-step range, but it works.

"William Sommerwerck" wrote in message
. ..

The dimmable CFLs I get from eBay (love those California lawmakers!)
have PF speced 0.90. I haven't got around to testing one, though.

What brand?

ULA, made you-know-where.

My understanding is that these bulbs are being sold in California for about
$1.00 each in Wal-Marts, with subsidy from the local power company.

I bought a dimmable GE two years ago, and it worked. You get only about 10
steps, at the top of the X-10's 256-step range, but it works.

The dimmable CFs I've been using have a standard Edison base and fit in
standard light bulb sockets. They are infinitely variable over a range that
goes down to pretty dark and then nothing, to full bright.

I use a few of them around the house, driven by standard wall-plate
residential dimmers.

I'm using 48 of them in 6 chandeliers driven by standard DMX-controlled
quad dimmer packs at church. Their brightness/drive curve is nonlinear, but
useable.

As you say, the color temperature is very constant over a usable range of
intensities compared to incadescent PAR bulbs. While they start pretty much
on the dime, they do get about 50% brighter the first minute or two of
operation.

If you've got the fixtures and ballasts that are designed for them,
4-terminal dimmable flourescents are marvelous. They dim over about the same
range of brightness and as linearly as an incadescent, but with constant
color temperature.

I use a few of them around the house, driven by standard
wall-plate residential dimmers.

Rheostats? Triacs? I'm not familiar with the current technology. (X-10 is
triac-controlled, I believe.)


As you say, the color temperature is very constant over a
usable range of intensities compared to incadescent PAR bulbs.

Actually, I didn't say that, but you'd expect it to be so, given that a
fluorescent lamp is a quantum device.


While they start pretty much on the dime, they do get about
50% brighter the first minute or two of operation.

That's what I noted with the Home Despot lamps. It was startling at first to
see a fluorescent lamp come on faster than an incandescent.

In comp.sys.ibm.pc.hardware.misc William Sommerwerck wrote:
I use a few of them around the house, driven by standard
wall-plate residential dimmers.

Rheostats? Triacs? I'm not familiar with the current technology. (X-10 is
triac-controlled, I believe.)


As you say, the color temperature is very constant over a
usable range of intensities compared to incadescent PAR bulbs.

Actually, I didn't say that, but you'd expect it to be so, given that a
fluorescent lamp is a quantum device.

Very much so, but mostly in the same sense that a glowing
pice of metal is a quantum device....

Arno