richard@gryphon.COM (Richard Sexton) (11/17/89)
Fluorescent lights have the potential to be very inexpensive
to operate, but sometimes, the cost of running fluorescent lights
is much higher than expected.
The reason for this is the type of ballast used to operate
the light. The ballast converts the electricity coming out
of the wall into the particular flavour of electricity the
fluorescent tube wants to see.
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. 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 efficient. A fixture with two 40 watt bulbs
may actually draw 250 watts.
The electronic ballast is the inverse of the magnetic ballast.
It is NOT cheap to buy, but it is silent and much
more efficient. On the order of 100 - 130 watts to run
two 40 watt tubes.
The state of the art in ballasts seems to belong to the Advance
corperation. They make two models, the REL2S40TP which
is comprised of discrete components, and has been around
for a while, and the newer RIC2S40TP which uses an ASIC
to replace all the discrete components. This unit has
to advantages over the older system. It is a ``smart''
ballast, in that it detects low voltage and maintains
constant luminous output by drawing more current. Secondly,
it will work with any 30 or 40 watt fluorescent tube -
enery saver, T-8's etc.
Thats the good news. The bad news is that they only make
one model. Indeed nobody makes an electronic ballast
that operates anything other that two 40 watt (or 30 watt)
tubes.
The reason for this is, 70% of fluorescent tubes sold
are the 48" 40 watt type, and it is not economical
at this point to manufacture electronic ballasts for
any other tube sizes.
--
``He is good with numbers, but I keep having to tell him how to
work the VCR over and over again'' -- Rajan Mahadevan's roommate
richard@gryphon.COM {routing site}!gryphon!richard rsd@sei.cmu.edu (Richard S D'Ippolito) (11/17/89)
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. 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.
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?
Rich
--
When you can measure what you are speaking about, and express it in numbers,
you know something about it.
Lord Kelvin rsd@sei.cmu.edu
-----------------------------------------------------------------------------larry@kitty.UUCP (Larry Lippman) (11/18/89)
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. <> Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp. <> UUCP {allegra|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> TEL 716/688-1231 | 716/773-1700 {hplabs|utzoo|uunet}!/ \uniquex!larry <> FAX 716/741-9635 | 716/773-2488 "Have you hugged your cat today?"
wb8foz@mthvax.cs.miami.edu (David Lesher) (11/18/89)
I was told once (by folks that ought to know) that as the tubes age, not only does the light output drop; but the power drawn increases. Thus the efficiency takes a double whammy. Comments? -- A host is a host & from coast to coast...wb8foz@mthvax.cs.miami.edu no one will talk to a host that's close..............(305) 255-RTFM Unless the host (that isn't close)......................pob 570-335 is busy, hung or dead....................................33257-0335
henkp@nikhefk.UUCP (Henk Peek) (11/19/89)
In article <3504@kitty.UUCP> larry@kitty.UUCP (Larry Lippman) writes: >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. A ballast inductor operates always in the non sataurable mode. When the iron saturates the inductance of the inductor goes very fast down and the current goes up. Henk Peek Henkp@nikhef.nl
larry@kitty.UUCP (Larry Lippman) (11/19/89)
In article <596@nikhefk.UUCP>, henkp@nikhefk.UUCP (Henk Peek) writes: > > The primary purpose of a ballast is for current limiting, and it > >therefore functions as a saturable inductor and not a transformer. > > A ballast inductor operates always in the non sataurable mode. > When the iron saturates the inductance of the inductor goes very fast down > and the current goes up. Not true where there is a capacitor and hence a resonant circuit involved, a design which is commonly found in fluorescent lamp circuits which employ no starter. In addition, some types of fluorescent lamp circuits employ a dual inductor with intentional magnetic field coupling. Such a device is usually called a "stray-field" or "leakage-reactance" transformer, although its characteristics are different from that of a conventional transformer so that current limiting can be provided. In a conventional transformer the mutual magnetic field which links both windings must be kept as high as possible in order to transfer the maximun energy. A stray-field transformer has reduced mutual magnetic flux, resulting in limited energy transfer. As increased load is drawn leakage flux increases and output voltage drops. A stray-field transformer in fluorescent lamp applications usually has common primary and secondary connections as in an autotransformer, and is also viewed by some as being two series inductors. Fluorescent lamp ballast circuits are more complex than one would imagine. <> Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp. <> UUCP {allegra|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> TEL 716/688-1231 | 716/773-1700 {hplabs|utzoo|uunet}!/ \uniquex!larry <> FAX 716/741-9635 | 716/773-2488 "Have you hugged your cat today?"
sorgatz@ttidca.TTI.COM ( Avatar) (11/19/89)
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. 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. + +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. + One point that seems missing, 25 years ago the lighting industry was not totally saturated with YUPPIE-MBA assholes! This has had a severe impact on the QUALITY of the Ballast transformers being produced. The older units that I have should last well into the next century..built like the proverbial brick privy! The newer transformers are made of thin, cheap steel and are just painted. The newer units run very hot and I've noticed they rust within a few months in humid climates. The older ones use thicker metal (hence they run cooler!) that is galvanized (hence they don't rust!) and then painted. Inside is another horror-story; the older ballasts had true-lamnate windings not so with the MBA-specials! The modern (read: cheap!) ballast is just set of windings (some don't even use copper wire! they use ALUMINUM on the really cheap Korean ones!) around a minimal core, some use a shell-core made of more cheap sheet steel. The case is usually filled with some polyu-foam, but I have seen some that are filled with ordinary black tar! Yeech! No wonder these things hum so bad! My 20+ year old transformers are audible, but just barely. Mostly you hear the tubes at 60Hz. In conclusion, the next time you curse cheaply made electrics of this ilk remember that the guys to blame are the so-called "Value Engineers"..most of whom DO NOT have an EE, and have next to no knowledge about anything except accounting. These are the bastards that insist on such garbage being sold in the marketplace. It is unfortunate that the management of most companies cannot distinguish between 'value' and 'cost'...they just keep letting the MBA-dickheads screw things up. ps- If you were asked by someone where YOU work to substitute inferior materials or workmanship in the job you do...would you comply? -- -Avatar-> (aka: Erik K. Sorgatz) KB6LUY +-------------------------+ Citicorp(+)TTI *----------> panic trap; type = N+1 * 3100 Ocean Park Blvd. (213) 450-9111, ext. 2973 +-------------------------+ Santa Monica, CA 90405 {csun,philabs,randvax,trwrb}!ttidca!ttidcb!sorgatz **
kenmoore@unix.cis.pitt.edu (Kenneth L Moore) (11/20/89)
In article <7835@ttidca.TTI.COM> sorgatz@ttidcb.tti.com (Erik Sorgatz - Avatar) writes: >In article <4995@ae.sei.cmu.edu> rsd@sei.cmu.edu (Richard S D'Ippolito) writes: >ps- If you were asked by someone where YOU work to substitute inferior >materials or workmanship in the job you do...would you comply? >-Avatar-> (aka: Erik K. Sorgatz) KB6LUY Clarify the circumstances... Does said yuppie MBA have the power to fire me? ;-) (And if he does, what the hell am I doing working here?)
tomb@hplsla.HP.COM (Tom Bruhns) (11/21/89)
Gosh, with 6 quick responses to arrive here already, I was thinking that this thread might provide me with some real information about fluorescent ballasts and driving fluorescent tubes. Does anyone out there actually have some good library references? In particular, I'd like to know both theoretical and practical aspects. What designs have proven practical? What sort of inverter designs do people use to drive fluorescents from DC supplies (both low voltage [5-15 volts] and moderate voltage [100-200 volts])? How is the life of a bulb affected by a DC component in the current? What other factors affect bulb life? BTW, I found the 250W a bit humorous. I mean, 250-2*40 leaves about 170 watts to dissipate in the ballast. Considering the size of the ballast, ... ! (Could Dick possibly have meant 250 VA? I hope not; that's a pretty poor power factor!) Tom Bruhns tomb%hplsla@hplabs.hp.com
wb8foz@mthvax.cs.miami.edu (David Lesher) (11/21/89)
At one point I heard a proposal to outfit large office buildings with ~260 volt power at several ten of khz. This would go to the lamps, which would have custom ballasts. The driving force was several % improvement in efficiency-- a double payoff since it also reduced the cooling load of the HVAC systems. It sounded like a workable idea. Nver heard any more, though. -- A host is a host & from coast to coast...wb8foz@mthvax.cs.miami.edu no one will talk to a host that's close..............(305) 255-RTFM Unless the host (that isn't close)......................pob 570-335 is busy, hung or dead....................................33257-0335
brian@ucsd.Edu (Brian Kantor) (11/21/89)
Many larger (most?) buildings use 277vac for the fluorescent lights. It's easy to get off the 416 three-phase and you can use thinner wire because the current is lower. Fries the @$#!# out of those home-style infrared motion detectors, though. - Brian
larry@kitty.UUCP (Larry Lippman) (11/22/89)
In article <1099@umigw.MIAMI.EDU>, wb8foz@mthvax.cs.miami.edu (David Lesher) writes: > At one point I heard a proposal to outfit large office buildings > with ~260 volt power at several ten of khz. This would go to the > lamps, which would have custom ballasts. The driving force was > several % improvement in efficiency-- a double payoff since it > also reduced the cooling load of the HVAC systems. This HAS been done in some experimental installations, but as far as I know, the concept just never caught on. The systems I am aware of used 400 and 600 volts at 3 kHz. For references check some backissues of "Illuminating Engineering" or the IES (Illuminating Engineering Society) Handboook. <> Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp. <> UUCP {allegra|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> TEL 716/688-1231 | 716/773-1700 {hplabs|utzoo|uunet}!/ \uniquex!larry <> FAX 716/741-9635 | 716/773-2488 "Have you hugged your cat today?"
rsd@sei.cmu.edu (Richard S D'Ippolito) (11/23/89)
In article <7835@ttidca.TTI.COM> Erik Sorgatz writes: > One point that seems missing, 25 years ago the lighting industry was not >totally saturated with YUPPIE-MBA assholes! This has had a severe impact >on the QUALITY of the Ballast transformers being produced. Hey, lighten up! I just purchased a new shop light for $9.99 (that's right) with two 40w tubes, fixture, cord and ballast. The ballast nameplate reads "120V 60Hz .85A", UL, minimun starting temperature 50 deg. F." I'll leave it as an exercise to the reader to decide whether or not it draws current equivalent to a 250watt load, whether the quoted figures I gave about power demand are dated, and whether the quality has gone down in 25 years. More enterprising folks might be able to calculate the power factor. Rich -- When you can measure what you are speaking about, and express it in numbers, you know something about it. Lord Kelvin rsd@sei.cmu.edu -----------------------------------------------------------------------------
torkil@psivax.UUCP (Torkil Hammer) (11/25/89)
In article <5068@ae.sei.cmu.edu> rsd@sei.cmu.edu (Richard S D'Ippolito) writes:
#
#with two 40w tubes, fixture, cord and ballast. The ballast nameplate reads
#"120V 60Hz .85A", UL, minimun starting temperature 50 deg. F."
#
#More enterprising folks might be able to calculate the power factor.
We can't do so without knowing the efficiency factor, aka cosine of phase
angle, which is measured as the ratio between watts and voltamperes.
Questions:
1. Why is there a minimum starting temp for the ballast?
2. Do today's ballasts come with a capacitor or other phase compensation
to optimize the irregular, but predictable, current pattern of flourescent
tubes?frankb@hpsad.HP.COM (Frank Ball) (11/27/89)
*From: torkil@psivax.UUCP (Torkil Hammer) *Questions: *1. Why is there a minimum starting temp for the ballast? It is harder to ionize the gas in the tube when it is cold. I had an old ballast that was getting weak, and couldn't start a cold tube, but if I took the tube out and warmed it up under my electric blacket it would fire up and work fine. Frank Ball frankb@hpsad.HP.COM
rsd@sei.cmu.edu (Richard S D'Ippolito) (11/30/89)
In article <2956@psivax.UUCP> Torkil Hammer writes: >In article <5068@ae.sei.cmu.edu> Richard S D'Ippolito writes: ># >#with two 40w tubes, fixture, cord and ballast. The ballast nameplate reads >#"120V 60Hz .85A", UL, minimun starting temperature 50 deg. F." ># >#More enterprising folks might be able to calculate the power factor. > >We can't do so without knowing the efficiency factor, aka cosine of phase >angle, which is measured as the ratio between watts and voltamperes. Sure you can -- make some assumptions about the limits: If the ballast is purely resistive, the power factor is 1.0 and the ballast dissipates 120V*0.85A - (2*40W) or 22 watts. If purely reactive, it dissipates zero watts and the power factor of the circuit is (2*40W)/102VA or 0.78. This should put an end to the erroneous claims for both outrageous ballast losses and low power factors. Note that worst case for ballast losses is best case for power factor, and v.v. So, if a typical ballast dissipates 15 watts, the power factor is on the order of 0.93. >Questions: >1. Why is there a minimum starting temp for the ballast? It has nothing to do with the ballast. The lamp must be above a certain temperature in order to get enough vaporized mercury to initiate the arc. >2. Do today's ballasts come with a capacitor or other phase compensation >to optimize the irregular, but predictable, current pattern of flourescent >tubes? The current pattern is very close to the voltage waveform; it is the phosphor characteristic that minimizes flicker. Some ballasts are lead-lag, so that the two tubes have their maximum brightness at slightly different times to reduce flicker. Also, good commercial/industrial installations will run the fixtures from alternate phases to reduce the strobe effect, especially where there is rotating machinery. Rich -- When you can measure what you are speaking about, and express it in numbers, you know something about it. Lord Kelvin rsd@sei.cmu.edu -----------------------------------------------------------------------------