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[Phys-l] Fwd: CFLs



from a friend

Begin forwarded message:

cut

Quality control is a problem in the U. S.
Not so in Germany, where the stuff also comes from China.
Price-Point problem?

CFLs have a computer type power supply. A direct coupled full wave bridge right across the line to a storage capacitor. No use of line frequency or grounds. Where is this voltage spike coming from?
Ballasts burn out from failing active parts in the inverter section, sometimes a protection resistor in series with a power output system when the transistor has NOT failed.
I had a fast short somewhere that kept burning out the main thermal protection , but after 2 changes, it burned out the short. Testing did not show a short.
In the old days the heater filaments opened from overuse (starts) or general metal migration and fatigue. Now the tube seems fine when the lamps go out.
With CFCs and incandescent, the greatest light efficiency comes when the units are running at high voltage and temperature and are stressed. Incadescents look (to me) best at 8% overvoltage. Nice and white (blue) and bright. They last less than half as long.
CFC's warm up to full brightness and work best with the ballast above (hot) yielding 15% more light (according to GE box on bulb) than with ballast down.
T.K.



cut

Install an MOV in the lighting line.

http://en.wikipedia.org/wiki/Surge_protector

Perhaps none of you have read: intro. phys. of harmonic distortion in fluorescent lamps?

AJP 71 (6) pp. 577 ff.


The article principally discusses the similarity of clarinet and fluorescent generation of harmonics, and includes the reason frequent cycling destroys the filament and that harmonic content in the mains supply shortens life. (without explanation)


http://scitation.aip.org/getpdf/servlet/GetPDFServlet? filetype=pdf&id=AJPIAS000071000006000577000001&idtype=cvips


bc found serendipitously while decluttering.

On 2009, Apr 09, , at 09:37, Shapiro, Mark wrote:

If you leave a CFL on for only a few minutes, you will shorten the life slightly from what I have observed here in my own house. If it's on for 15 minutes or more you should not shorten its live appreciably.

All the anecdotes that I've read here about short-lived CFLs point to "dirty" power. If you suspect that you have "dirty" power (lots of voltage spikes), ask your power company to put a recording voltage monitor on your line. They are obligated to clean up the situation, because that dirty power is shortening the life of everything you have on the line.

Mark


________________________________________
From: phys-l-bounces@carnot.physics.buffalo.edu [phys-l- bounces@carnot.physics.buffalo.edu] On Behalf Of Bill Nettles [bnettles@uu.edu]
Sent: Thursday, April 09, 2009 8:31 AM
To: Forum for Physics Educators
Subject: Re: [Phys-l] CFLs

The anecdotes I'm getting (mainly from web pages) say that turning CFL's on and off with short on-times drastically shortens the ballast lifetime. If that's true, then we shouldn't be using CFL's in bedrooms and bathrooms because of the environmental impacts of manufacturing and disposing CFL's (plastic, electronics, mercury, more glass) as compared to incands. I already have fluorescents in the kitchen, and I use CFL's on the porch for night security lights. If you say, "just leave them on longer" then what's the point? Either I turn off the incandescent and use less energy, or I leave the CFL on so that the lifetime is long, but I use the same energy as the incand. because I leave it on longer....sigh.

BTW, the CFL's I've bought are "designed" (according to the package) to be used in recessed lighting with the ballast end up. Maybe there are voltage fluctuation problems in my house, BUT...

Back to my original bottom line---the CFL ballasts need some good engineering so that they stand up to the rigors of REAL LIFE....frequent on-off cycling, voltage fluctuations, ground loops. CFL is a good idea in general, but the products aren't good enough yet....I vote for getting the LED costs down.

Bill N

James Mackey <jmackey@harding.edu> 4/8/2009 4:57 pm >>>
I have sitting on my desk right now a sack of 6 CFL's that all died within 6
months. There are GE's, Sylvania's, and Sunbeam's bulbs. This has been my
experience with CFLs over the last 3 years. I am about to go back to
incandescents which are much cheaper, by my rough calculations, about 1/2
the cost including the more energy use and purchase price. These were used
in interior fixtures except for one bulb which lasted as long a any of the
others. I would like to be able to justify CFLs but based on my small
sample, they do not justify their price. I have not even included the
disposal problem, since they all (I believe) have small amounts of mercury
in the bulb. If these are the bulbs of the future, they clearly need
additional work!
Waiting for LED bulbs to cheapen!
James Mackey

On Tue, Apr 7, 2009 at 2:19 PM, <lhodges@iastate.edu> wrote:


I use CFLs in some places, but I'm very disappointed in their
lifetimes...not
even close to "7X longer." More like the same life as incandescent. If it
weren't for the extreme heat that the incand. in the bathroom give off for
the
same light, I'd go back. CFL ballasts need some vast improvements, you may
save
on the electric bill, but you pay $$ for the product.

I've been using CFLs for over 20 years, since they were fairly new and
unknown
but available at some stores (like electric-supply stores). I bought every
type
I could find (GE, Sylvania, Lites of America, Philips, etc.) and kept
records on
them. I used some in our unheated garage, leaving them on all the time
except
for turning them off several times a day for a few minutes. All but one
brand
(Lites of America) easily lasted the 10,000 hours claimed. So I've placed
them
in all the light fixtures I could, where they last under normal use for
many
years. I don't use them outside (slow to brighten up in cold weather) and
don't
use them with dimmer switches. Several are in locations where they are on
for
several hours every night. I'm very pleased with them. Since they aren't
burning out I haven't bought any for a few years - maybe they aren't as
good -
but I suspect many users just want something to complain about.

Along similar lines, when the low-flush toilets became available, there
were
many complaints about them from homeowners forced to use them. As I had
good
working toilets I didn't pay much attention to them. Then one day I
decided one
of our toilets which had never been a good flusher, for some reason, ought
to be
replaced. The new low-flush toilet, to my surprise, was excellent, and
remains
the best toilet in our house.

Laurent Hodges
writing from the inside of his passive solar home, heated for the last few
days
exclusively by the sun, despite the cold temperatures.