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From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.electronics
Subject: Re: Fluorescent light ballasts
Summary: Efficiency of fluorescent lamps...
Keywords: advance
Message-ID: <3504@kitty.UUCP>
Date: 18 Nov 89 05:10:22 GMT
References: <22334@gryphon.COM> <4995@ae.sei.cmu.edu>
Organization: Recognition Research Corp., Clarence, NY
Lines: 45

In article <4995@ae.sei.cmu.edu>, rsd@sei.cmu.edu (Richard S D'Ippolito) writes:
> In article <22334@gryphon.COM> richard@gryphon.COM (Richard Sexton) writes:
> =There are two kinds of ballasts: magnetic and elecronic. The
> =former is by far the most common type, and is little more than
> =a transformer.

	The primary purpose of a ballast is for current limiting, and it
therefore functions as a saturable inductor and not a transformer.  The
simplest ballast is merely a series inductor.  Depending upon the size,
wattage and operating voltage of the lamps, a ballast may also function
as an auto-transfomer for increased voltage at the time of starting ONLY;
once the lamp fires, the voltage is then LESS than the AC line.

> = It is cheap to puchase. It has the drawbacks
> =of being noisy (this is the source of the humm, or buzzing
> =so often ascociated with fluorescent lights) and not
> =terribly energt [sic]  efficient. A fixture with two 40 watt bulbs
> =may actually draw 250 watts.

	Utter nonsense!

> Twentyfive years ago, when I did lighting design, the typical transformer
> ballasts for two 40W tubes consumed less than 20W, making the total fixture
> demand less than 100W.  I know this because I also had to calculate the
> air-conditioning load.
> 
> What are you talking about?!  Is this some hype from an electronic ballast
> manufacturer?

	Richard Sexton's comments are bogus, and I suspect he is suffering
from a case of the bends as a result of being immersed in his sci.aquaria
fiasco for too long.

	In any event, Richard D'Ippolito is quite correct.  Fluorescent
lamps are quite efficient with respect to ballast losses, having a range
of 20% loss at worse case and 95% loss at best.

	Therefore, a 2-lamp 40-watt fixture of say, a rapid-start variety
will consume no more than 100 watts of energy when operated at rated
voltage.

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