Science and Technology news... :: View topic - voltage drop and dimmable fluorescent ballasts

Don Klipstein · Guest

In <K2hFk.58914$Mh5.726@bgtnsc04-news.ops.worldnet.att.net>, TKM wrote:
[quote]
"Don Klipstein" <don@manx.misty.com> wrote in message
news:slrngeajcl.8dr.don@manx.misty.com...
In article <6kk2m8F894ltU1@mid.individual.net>, JB wrote in part:
I snip to edit for space
The metallurgy of these filaments is rather special as you would expect.
Actually though, tungsten filaments are more fragile when cold.

My experience tells me otherwise.

If I drop or bang an incandescent lamp that has long wires leading
to the filament, and do so while the filament is cold, I find it hard (but
not impossible) to break or stretch the filament without also bending the
wires leading to the filament.

When the filament is hot, I find it easy to stretch the filament out of
shape by so much as rough tapping of the lamp. Sometimes, worse still, I
end up stretching only part of the filament - and that can make the
unstretched portion hotter than before. (The stretched portion is cooler,
has less resistance, and more current flows through the entire filament.)
Also, uneven filament temperature leads to uneven evaporation, and the
hotter parts of the filament become acceleratingly severe hot spots once
significant evaporation has occurred.

And if there is a lot of vibration just short of stretching the
filament, that will cause significant metal fatigue. I think that is more
of a problem with a hot filament than with a cold one.

Incandescent trouble lights seem to me to easily have their filaments
stretched out of shape or outright broken from impacts while they are on
and not while they are off.

I don>t think its so much the stretching of the filament as it is the
shorting of the coils in the coiled-coil filament. When line voltage lamps,
particularly halogen, are moved or subjected to vibration, the coils bang
together and short circuit. That makes the voltage goes up on the remaining
length of filament which then fails or burns hotter shortening life. The
50PAR20 is particularly sensitive and requires very gentle handling when
aiming the fixture.
[/quote]
Oh you remind me! I have a bit of experience with filaments partially
short in 120V lamps from shock/vibration!

I have seen that happen with filaments of C-7A and CC-2V style.

In the case of C-7A: Nightlight lamps and similar 120V holiday lamps,
when tapped in rough manner by a finger (plucked), especialy if
impacted such several times, can have a small region of filament get
tangled with a small region of a nearby portion of filament.
This appears to me to occur more easily if impacts (with the filament
hot) stretch the filament so that the filament has slack and sections of
it easily flopping around.
I used to do that a bit as a "party trick" - to make such lamps glow
brighter and whiter. That was maybe 30 years ago, and back then I was not
thinking that much that I reduced the lamp>s life expectancy to maybe a
few days.
On a bit of a sidetrack, those lamps had bulb shape/size designation of
C7 and a common nominal wattage for those was 7 watts. Since then there
have been 4 and nowadays some 5 watt ones with C7 bulb and C-7A filament.
There is a larger usually-colored "older type holiday lamp" with bulb
shape/size designation of C9. Its wattage is typically 7 or 10 watts and
the filament is usually C-7A. The base of that one is often "intermediate
screw", which often makes the part number get an "N" towards the end.

In the case of CC-2V: I forget whether that was "normal CC-2V"
(pointing away from base) or inverted (and I wonder what the designation
for that is anyway). However, those were V-shaped coiled-coil filaments
with one support at the "corner" between the ends.
The lamp was a chandalier style one, of wattage probably 40 or 60 watts
but I can>t rule out 25, and the bulb was of one of those F or similar
flame shapes.
Where I saw such lamps having filaments partially shorting, the
filaments had a short somewhat close to "the vertex of the V", apparently
due to vibration/shock jostling the filaments and possibly stretching the
filaments also to make the filaments entangle into such "partial shorts"
more easily.
Where I saw such CC-2V filaments shorting was in a fraternity house at
the University of Pennsylvania (when I was making a delivery to that
house), back in a day when fraternities at U-of-P had an easier time
having parties with beer kegs in their houses. The affected/afflected
filaments appeared to me especially "stretched/floppy", except the ones
that partially shorted but had yet to fail appeared to me "not-too-floppy"
(and also appeared to me having fair to poor chance of surviving into the
next party).
I did appear to me that the filaments were stretched into a "floppier
state" and I happen to think that the filaments were stretched into an
"easier-to-partially-short state" while the filaments were hot, as in
"in-use to produce light".

As for shorting effects specific to coiled-coil where "greater turns"
short to adjacent ones - that one I have yet to see, but I don>t yet have
doubt that this one can occur if the "greater turns" are wider and/or
the "compacted overall length" is shorter than usually used in coiled-coil
C-6/C-8 filaments in 120V A19 lamps.

- Don Klipstein (don@misty.com)

Travis Evans · Guest

On Sat, 4 Oct 2008 05:06:22 +0000 (UTC), Don Klipstein
<don@manx.misty.com> wrote:
[quote]Oh you remind me! I have a bit of experience with filaments partially
short in 120V lamps from shock/vibration!

I have seen that happen with filaments of C-7A and CC-2V style.

In the case of C-7A: Nightlight lamps and similar 120V holiday lamps,
when tapped in rough manner by a finger (plucked), especialy if
impacted such several times, can have a small region of filament get
tangled with a small region of a nearby portion of filament.
[/quote]
Maybe I>ve seen that effect before. I remember several years ago when
my stepbrothers were playing with a burned-out nightlight. When shaken
a certain way (presumably in a manner that made the broken ends of the
filament rest against each other) it would still light up and seemed
somewhat brighter than it normally would be. At the time I didn>t feel
comfortable with them playing with the lamp in this way since I wasn>t
sure whether there was any danger in it.

It seems that I have seen a similar thing happen with burned-out
nightlights on a couple of other occassions, but can>t remember for
sure.

--
Travis Evans
[Obtain email address by removing all Q>s.]

TKM · Guest

"Don Klipstein" <don@manx.misty.com> wrote in message
news:slrngeduee.aof.don@manx.misty.com...
[quote]In <K2hFk.58914$Mh5.726@bgtnsc04-news.ops.worldnet.att.net>, TKM wrote:

"Don Klipstein" <don@manx.misty.com> wrote in message
news:slrngeajcl.8dr.don@manx.misty.com...
In article <6kk2m8F894ltU1@mid.individual.net>, JB wrote in part:
I snip to edit for space
The metallurgy of these filaments is rather special as you would expect.
Actually though, tungsten filaments are more fragile when cold.

My experience tells me otherwise.

If I drop or bang an incandescent lamp that has long wires leading
to the filament, and do so while the filament is cold, I find it hard
(but
not impossible) to break or stretch the filament without also bending
the
wires leading to the filament.

When the filament is hot, I find it easy to stretch the filament out of
shape by so much as rough tapping of the lamp. Sometimes, worse still,
I
end up stretching only part of the filament - and that can make the
unstretched portion hotter than before. (The stretched portion is
cooler,
has less resistance, and more current flows through the entire
filament.)
Also, uneven filament temperature leads to uneven evaporation, and the
hotter parts of the filament become acceleratingly severe hot spots once
significant evaporation has occurred.

And if there is a lot of vibration just short of stretching the
filament, that will cause significant metal fatigue. I think that is
more
of a problem with a hot filament than with a cold one.

Incandescent trouble lights seem to me to easily have their filaments
stretched out of shape or outright broken from impacts while they are on
and not while they are off.

I don>t think its so much the stretching of the filament as it is the
shorting of the coils in the coiled-coil filament. When line voltage
lamps,
particularly halogen, are moved or subjected to vibration, the coils bang
together and short circuit. That makes the voltage goes up on the
remaining
length of filament which then fails or burns hotter shortening life. The
50PAR20 is particularly sensitive and requires very gentle handling when
aiming the fixture.

Oh you remind me! I have a bit of experience with filaments partially
short in 120V lamps from shock/vibration!

I have seen that happen with filaments of C-7A and CC-2V style.

In the case of C-7A: Nightlight lamps and similar 120V holiday lamps,
when tapped in rough manner by a finger (plucked), especialy if
impacted such several times, can have a small region of filament get
tangled with a small region of a nearby portion of filament.
This appears to me to occur more easily if impacts (with the filament
hot) stretch the filament so that the filament has slack and sections of
it easily flopping around.
I used to do that a bit as a "party trick" - to make such lamps glow
brighter and whiter. That was maybe 30 years ago, and back then I was not
thinking that much that I reduced the lamp>s life expectancy to maybe a
few days.
On a bit of a sidetrack, those lamps had bulb shape/size designation of
C7 and a common nominal wattage for those was 7 watts. Since then there
have been 4 and nowadays some 5 watt ones with C7 bulb and C-7A filament.
There is a larger usually-colored "older type holiday lamp" with bulb
shape/size designation of C9. Its wattage is typically 7 or 10 watts and
the filament is usually C-7A. The base of that one is often "intermediate
screw", which often makes the part number get an "N" towards the end.

In the case of CC-2V: I forget whether that was "normal CC-2V"
(pointing away from base) or inverted (and I wonder what the designation
for that is anyway). However, those were V-shaped coiled-coil filaments
with one support at the "corner" between the ends.
The lamp was a chandalier style one, of wattage probably 40 or 60 watts
but I can>t rule out 25, and the bulb was of one of those F or similar
flame shapes.
Where I saw such lamps having filaments partially shorting, the
filaments had a short somewhat close to "the vertex of the V", apparently
due to vibration/shock jostling the filaments and possibly stretching the
filaments also to make the filaments entangle into such "partial shorts"
more easily.
Where I saw such CC-2V filaments shorting was in a fraternity house at
the University of Pennsylvania (when I was making a delivery to that
house), back in a day when fraternities at U-of-P had an easier time
having parties with beer kegs in their houses. The affected/afflected
filaments appeared to me especially "stretched/floppy", except the ones
that partially shorted but had yet to fail appeared to me "not-too-floppy"
(and also appeared to me having fair to poor chance of surviving into the
next party).
I did appear to me that the filaments were stretched into a "floppier
state" and I happen to think that the filaments were stretched into an
"easier-to-partially-short state" while the filaments were hot, as in
"in-use to produce light".

As for shorting effects specific to coiled-coil where "greater turns"
short to adjacent ones - that one I have yet to see, but I don>t yet have
doubt that this one can occur if the "greater turns" are wider and/or
the "compacted overall length" is shorter than usually used in coiled-coil
C-6/C-8 filaments in 120V A19 lamps.

- Don Klipstein (don@misty.com)
[/quote]
Tungsten filaments, when new, are relatively stiff and I>m not convinced
that they stretch although they certainly flop around and they do move
inside the filament support loops . Try this (it requires sacrificing a new
lamp, however): Take a candelabra-based lamp apart. They typically have,
as you say, CC-2V filaments although some have C-7A designs (more filament
supports). Remove the filament and pull on the ends. It takes quite a bit
of force to stretch that filament, so even after some burning hours as the
filament becomes brittle, it doesn>t seem likely that it stretches. But, if
so, the "CC" filament would stretch more than the "C" types.

A story was told to me some years ago by the product service people of a
large lamp manufacturer. It seems that they had received a complaint about
short lamp life of candelabra-based lamps in a dining room chandelier. The
complaint was puzzling since dozens of lamps had failed over a few weeks
time and there were no other complaints pending for that particular lamp
type. The person complaining happened to be fairly close to the offices of
the company so a local lamp engineer was dispatched to see what the problem
might be. An evening visit was arranged and the engineer confirmed that
lamps were indeed failing, but that the lamps were current production and
the voltage at the lamp sockets was below the lamp rating. There was no
dimmer on the circuit. Puzzled, the lamp engineer left a voltage recording
device on the circuit and arranged another visit for a week later.

That visit turned up more failed lamps, a record of less-then-rated voltage
on the lines and an increasingly-grumpy customer. As the frustrated
engineer was about to leave, however, there was a loud thump from upstairs
that shook the whole room including the chandelier which actually moved
several inches. Problem solved. The noise was due to the teenage son
jumping from the top level of a bunk bed onto the bedroom floor which he
did, with some pleasure, several times a day. A gym pad on the bedroom
floor damped the worst of the vibrations and reduced lamp failures; but the
problem wasn>t solved until the bunk bed was moved to another bedroom.

The episode generated research on filament failures and a technical paper
written a few years later concluded that vibration and shock failures in
small decorative lamps accounted for a fair percentage (30-50%, as I recall)
of failures before rated life.

Terry McGowan

TKM · Guest

"Travis Evans" <travisgevansQ@coxQ.netQ> wrote in message
news:PVEFk.13303$I44.9995@newsfe03.iad...
[quote]On Sat, 4 Oct 2008 05:06:22 +0000 (UTC), Don Klipstein
don@manx.misty.com> wrote:
Oh you remind me! I have a bit of experience with filaments partially
short in 120V lamps from shock/vibration!

I have seen that happen with filaments of C-7A and CC-2V style.

In the case of C-7A: Nightlight lamps and similar 120V holiday lamps,
when tapped in rough manner by a finger (plucked), especialy if
impacted such several times, can have a small region of filament get
tangled with a small region of a nearby portion of filament.

Maybe I>ve seen that effect before. I remember several years ago when
my stepbrothers were playing with a burned-out nightlight. When shaken
a certain way (presumably in a manner that made the broken ends of the
filament rest against each other) it would still light up and seemed
somewhat brighter than it normally would be. At the time I didn>t feel
comfortable with them playing with the lamp in this way since I wasn>t
sure whether there was any danger in it.

It seems that I have seen a similar thing happen with burned-out
nightlights on a couple of other occassions, but can>t remember for
sure.

--
Travis Evans
[Obtain email address by removing all Q>s.]
[/quote]
Shaking and/or sharply tapping a small C7 or C9 line-voltage lamp does
sometimes "repair" it. What happens is the broken ends of the filament
swing around and if they happen to touch, the arc which is generated welds
the filament pieces together. The weld is weak and it>s likely that the
filament is now shorter than before, so the lamp burns brighter before it
fails agan. But, it can burn for many hours. I>ve done such a repair on
holiday lamps many times with no nasty results; but, of course, the lamp can
break if hit too hard and there>s a small chance of the filament arcing into
the lamp base through the filament support wires.

Terry McGowan

Travis Evans · Guest

On Sat, 04 Oct 2008 14:52:17 GMT, TKM <nomail@no.net> wrote:
[quote]Shaking and/or sharply tapping a small C7 or C9 line-voltage lamp does
sometimes "repair" it. What happens is the broken ends of the filament
swing around and if they happen to touch, the arc which is generated welds
the filament pieces together. The weld is weak and it>s likely that the
filament is now shorter than before, so the lamp burns brighter before it
fails agan. But, it can burn for many hours. I>ve done such a repair on
holiday lamps many times with no nasty results; but, of course, the lamp can
break if hit too hard and there>s a small chance of the filament arcing into
the lamp base through the filament support wires.
[/quote]
This reminds me of a history article on a streetlamp collector>s website
about incandescent streetlights in the early days. Many of these at
the time were in series circuits where the voltage of a circuit with
many lamps could easily be in the hundreds or even thousands of volts.
It mentioned that often a series lamp with a breaking filament would
be welded back together by the high-voltage arc and that this would
often happen to the same lamp repeatedly over time. The article said
that the effective filament length would become shorter and that these
lamps would become dimmer and redder instead of failing to light
altogether.

--
Travis Evans
[Obtain email address by removing all Q>s.]

TKM · Guest

"Travis Evans" <travisgevansQ@coxQ.netQ> wrote in message
news:8CLFk.236$OY7.165@newsfe06.iad...
[quote]On Sat, 04 Oct 2008 14:52:17 GMT, TKM <nomail@no.net> wrote:
Shaking and/or sharply tapping a small C7 or C9 line-voltage lamp does
sometimes "repair" it. What happens is the broken ends of the filament
swing around and if they happen to touch, the arc which is generated
welds
the filament pieces together. The weld is weak and it>s likely that the
filament is now shorter than before, so the lamp burns brighter before it
fails agan. But, it can burn for many hours. I>ve done such a repair on
holiday lamps many times with no nasty results; but, of course, the lamp
can
break if hit too hard and there>s a small chance of the filament arcing
into
the lamp base through the filament support wires.

This reminds me of a history article on a streetlamp collector>s website
about incandescent streetlights in the early days. Many of these at
the time were in series circuits where the voltage of a circuit with
many lamps could easily be in the hundreds or even thousands of volts.
It mentioned that often a series lamp with a breaking filament would
be welded back together by the high-voltage arc and that this would
often happen to the same lamp repeatedly over time. The article said
that the effective filament length would become shorter and that these
lamps would become dimmer and redder instead of failing to light
altogether.

--
Travis Evans
[Obtain email address by removing all Q>s.]
[/quote]
That>s a great example since no matter how short the filament, the same
current would go through it and the lumen output of the lamp would be a
function of the length of filament remaining. The redder output results
from the reduced lamp wattage and lower filament temperature.

Terry McGowan

Andrew Gabriel · Guest

In article <meSFk.60643$Mh5.48444@bgtnsc04-news.ops.worldnet.att.net>,
"TKM" <nomail@no.net> writes:
[quote]
"Travis Evans" <travisgevansQ@coxQ.netQ> wrote in message
news:8CLFk.236$OY7.165@newsfe06.iad...
On Sat, 04 Oct 2008 14:52:17 GMT, TKM <nomail@no.net> wrote:
Shaking and/or sharply tapping a small C7 or C9 line-voltage lamp does
sometimes "repair" it. What happens is the broken ends of the filament
swing around and if they happen to touch, the arc which is generated
welds
the filament pieces together. The weld is weak and it>s likely that the
filament is now shorter than before, so the lamp burns brighter before it
fails agan. But, it can burn for many hours. I>ve done such a repair on
holiday lamps many times with no nasty results; but, of course, the lamp
can
break if hit too hard and there>s a small chance of the filament arcing
into
the lamp base through the filament support wires.

This reminds me of a history article on a streetlamp collector>s website
about incandescent streetlights in the early days. Many of these at
the time were in series circuits where the voltage of a circuit with
many lamps could easily be in the hundreds or even thousands of volts.
It mentioned that often a series lamp with a breaking filament would
be welded back together by the high-voltage arc and that this would
often happen to the same lamp repeatedly over time. The article said
that the effective filament length would become shorter and that these
lamps would become dimmer and redder instead of failing to light
altogether.

That>s a great example since no matter how short the filament, the same
current would go through it and the lumen output of the lamp would be a
function of the length of filament remaining. The redder output results
from the reduced lamp wattage and lower filament temperature.
[/quote]
A council lighting engineer gave me a dead one of these lamps.
It was rated 300W 5.5A IIRC, but no voltage specification, being
designed for series operation. I was told it has something in the
lamp base which shorts out when the filament breaks and a few
thousand volts appear across it, so the others stay on (a bit like
fairy lights). They stopped being able to obtain the series filament
lamps sometime before 1970 and had to swap them out for mercury
vapour lamps whose control gear was designed to run on a series
circuit. (In the mid-late 1970>s, those were all changed to LPS
lamps, but I think the series wiring was abandoned at that point.)
Some years later, I saw the series loop power supplies in the
basement of the town hall, although it was no longer used at that
point. Quite fancy constant current transformers which had a core
which moved depending how many lamps were shorted (someone had
marked the core positions for various numbers of dead lamps).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Travis Evans · Guest

On 04 Oct 2008 23:01:10 GMT, Andrew Gabriel <andrew@cucumber.demon.co.uk> wrote:
[quote]In article <meSFk.60643$Mh5.48444@bgtnsc04-news.ops.worldnet.att.net>,
"TKM" <nomail@no.net> writes:

"Travis Evans" <travisgevansQ@coxQ.netQ> wrote in message
news:8CLFk.236$OY7.165@newsfe06.iad...
This reminds me of a history article on a streetlamp collector>s website
about incandescent streetlights in the early days. Many of these at
the time were in series circuits where the voltage of a circuit with
many lamps could easily be in the hundreds or even thousands of volts.
It mentioned that often a series lamp with a breaking filament would
be welded back together by the high-voltage arc and that this would
often happen to the same lamp repeatedly over time. The article said
that the effective filament length would become shorter and that these
lamps would become dimmer and redder instead of failing to light
altogether.

That>s a great example since no matter how short the filament, the same
current would go through it and the lumen output of the lamp would be a
function of the length of filament remaining. The redder output results
from the reduced lamp wattage and lower filament temperature.

A council lighting engineer gave me a dead one of these lamps.
It was rated 300W 5.5A IIRC, but no voltage specification, being
designed for series operation. I was told it has something in the
lamp base which shorts out when the filament breaks and a few
thousand volts appear across it, so the others stay on (a bit like
fairy lights).
[...]
[/quote]
The article I read said that they used a piece of mica or other
material placed in the socket below the lamp that would short, and some
of these lamps also had the lead-in wires designed so that they would
short together on failure to prevent the arc from making its way into
the socket and destroying it.

--
Travis Evans
[Obtain email address by removing all Q>s.]

JohnR66 · Guest

"TKM" <nomail@no.net> wrote in message
news:heLFk.254731$102.213004@bgtnsc05-news.ops.worldnet.att.net...
[quote]
"Don Klipstein" <don@manx.misty.com> wrote in message
news:slrngeduee.aof.don@manx.misty.com...
In <K2hFk.58914$Mh5.726@bgtnsc04-news.ops.worldnet.att.net>, TKM wrote:

"Don Klipstein" <don@manx.misty.com> wrote in message
news:slrngeajcl.8dr.don@manx.misty.com...
In article <6kk2m8F894ltU1@mid.individual.net>, JB wrote in part:
I snip to edit for space
The metallurgy of these filaments is rather special as you would
expect.
Actually though, tungsten filaments are more fragile when cold.

My experience tells me otherwise.

If I drop or bang an incandescent lamp that has long wires leading
to the filament, and do so while the filament is cold, I find it hard
(but
not impossible) to break or stretch the filament without also bending
the
wires leading to the filament.

When the filament is hot, I find it easy to stretch the filament out
of
shape by so much as rough tapping of the lamp. Sometimes, worse still,
I
end up stretching only part of the filament - and that can make the
unstretched portion hotter than before. (The stretched portion is
cooler,
has less resistance, and more current flows through the entire
filament.)
Also, uneven filament temperature leads to uneven evaporation, and the
hotter parts of the filament become acceleratingly severe hot spots
once
significant evaporation has occurred.

And if there is a lot of vibration just short of stretching the
filament, that will cause significant metal fatigue. I think that is
more
of a problem with a hot filament than with a cold one.

Incandescent trouble lights seem to me to easily have their filaments
stretched out of shape or outright broken from impacts while they are
on
and not while they are off.

I don>t think its so much the stretching of the filament as it is the
shorting of the coils in the coiled-coil filament. When line voltage
lamps,
particularly halogen, are moved or subjected to vibration, the coils bang
together and short circuit. That makes the voltage goes up on the
remaining
length of filament which then fails or burns hotter shortening life. The
50PAR20 is particularly sensitive and requires very gentle handling when
aiming the fixture.

Oh you remind me! I have a bit of experience with filaments partially
short in 120V lamps from shock/vibration!

I have seen that happen with filaments of C-7A and CC-2V style.

In the case of C-7A: Nightlight lamps and similar 120V holiday lamps,
when tapped in rough manner by a finger (plucked), especialy if
impacted such several times, can have a small region of filament get
tangled with a small region of a nearby portion of filament.
This appears to me to occur more easily if impacts (with the filament
hot) stretch the filament so that the filament has slack and sections of
it easily flopping around.
I used to do that a bit as a "party trick" - to make such lamps glow
brighter and whiter. That was maybe 30 years ago, and back then I was
not
thinking that much that I reduced the lamp>s life expectancy to maybe a
few days.
On a bit of a sidetrack, those lamps had bulb shape/size designation of
C7 and a common nominal wattage for those was 7 watts. Since then there
have been 4 and nowadays some 5 watt ones with C7 bulb and C-7A filament.
There is a larger usually-colored "older type holiday lamp" with bulb
shape/size designation of C9. Its wattage is typically 7 or 10 watts and
the filament is usually C-7A. The base of that one is often
"intermediate
screw", which often makes the part number get an "N" towards the end.

In the case of CC-2V: I forget whether that was "normal CC-2V"
(pointing away from base) or inverted (and I wonder what the designation
for that is anyway). However, those were V-shaped coiled-coil filaments
with one support at the "corner" between the ends.
The lamp was a chandalier style one, of wattage probably 40 or 60 watts
but I can>t rule out 25, and the bulb was of one of those F or similar
flame shapes.
Where I saw such lamps having filaments partially shorting, the
filaments had a short somewhat close to "the vertex of the V", apparently
due to vibration/shock jostling the filaments and possibly stretching the
filaments also to make the filaments entangle into such "partial shorts"
more easily.
Where I saw such CC-2V filaments shorting was in a fraternity house at
the University of Pennsylvania (when I was making a delivery to that
house), back in a day when fraternities at U-of-P had an easier time
having parties with beer kegs in their houses. The affected/afflected
filaments appeared to me especially "stretched/floppy", except the ones
that partially shorted but had yet to fail appeared to me
"not-too-floppy"
(and also appeared to me having fair to poor chance of surviving into the
next party).
I did appear to me that the filaments were stretched into a "floppier
state" and I happen to think that the filaments were stretched into an
"easier-to-partially-short state" while the filaments were hot, as in
"in-use to produce light".

As for shorting effects specific to coiled-coil where "greater turns"
short to adjacent ones - that one I have yet to see, but I don>t yet have
doubt that this one can occur if the "greater turns" are wider and/or
the "compacted overall length" is shorter than usually used in
coiled-coil
C-6/C-8 filaments in 120V A19 lamps.

- Don Klipstein (don@misty.com)

Tungsten filaments, when new, are relatively stiff and I>m not convinced
that they stretch although they certainly flop around and they do move
inside the filament support loops . Try this (it requires sacrificing a
new lamp, however): Take a candelabra-based lamp apart. They typically
have, as you say, CC-2V filaments although some have C-7A designs (more
filament supports). Remove the filament and pull on the ends. It takes
quite a bit of force to stretch that filament, so even after some burning
hours as the filament becomes brittle, it doesn>t seem likely that it
stretches. But, if so, the "CC" filament would stretch more than the "C"
types.

A story was told to me some years ago by the product service people of a
large lamp manufacturer. It seems that they had received a complaint
about short lamp life of candelabra-based lamps in a dining room
chandelier. The complaint was puzzling since dozens of lamps had failed
over a few weeks time and there were no other complaints pending for that
particular lamp type. The person complaining happened to be fairly close
to the offices of the company so a local lamp engineer was dispatched to
see what the problem might be. An evening visit was arranged and the
engineer confirmed that lamps were indeed failing, but that the lamps were
current production and the voltage at the lamp sockets was below the lamp
rating. There was no dimmer on the circuit. Puzzled, the lamp engineer
left a voltage recording device on the circuit and arranged another visit
for a week later.

That visit turned up more failed lamps, a record of less-then-rated
voltage on the lines and an increasingly-grumpy customer. As the
frustrated engineer was about to leave, however, there was a loud thump
from upstairs that shook the whole room including the chandelier which
actually moved several inches. Problem solved. The noise was due to the
teenage son jumping from the top level of a bunk bed onto the bedroom
floor which he did, with some pleasure, several times a day. A gym pad
on the bedroom floor damped the worst of the vibrations and reduced lamp
failures; but the problem wasn>t solved until the bunk bed was moved to
another bedroom.

The episode generated research on filament failures and a technical paper
written a few years later concluded that vibration and shock failures in
small decorative lamps accounted for a fair percentage (30-50%, as I
recall) of failures before rated life.

Terry McGowan

[/quote]
One way to see the filimament move is to place a magnet near the lamp when
on (operating on AC). I did that with with a C7 nightlight bulb and and it
vibrated itself into a shorted section. I unplugged it and tapped it back
loose.

When I lived in an appartment, The upstairs tennant must have jumped hard or
dropped something so heavy a U tube CFL in my ceiling fixture hit against
the glass cover and broke. I>m glad to be out of appartments. There>s
allways those neighbors. Especially ones with the music.

Jeff Jonas · Guest

[quote]Stage effects lighting has "Blacklight" UV LEDs. It>s rather difficult
to get real specifications from some of these outfits, so I>m not sure
of the details.

I recall seeing references to UV cureing sources that are LED.
[/quote]
I just read a full page ad/info in Design News
about HPUV: high power ultraviolet LEDs

The page links to
http://www.em.avnet.com/LightSpeed
particularly
LM06: Exploring High-Power Ultraviolet LEDs
http://www.em.avnet.com/ctf_shared/sta/df2df2usa/LightSpeed-Eskow-1206.pdf

I.N. Galidakis · Guest

Andrew Gabriel wrote:
[quote]In article <1224847316.246031@athprx04>,
"I.N. Galidakis" <morpheus@olympus.mons> writes:
Victor Roberts wrote:
On Mon, 29 Sep 2008 15:10:25 +0300, "I.N. Galidakis"
morpheus@olympus.mons> wrote:

Travis Evans wrote:
[snip]

Do phosphored mercury lamps have generally shorter warm-up times for
some reason, ...?

Yes, they do. The phosphor redirects some of the radiation back to the
burner and as a result the burner reaches optimal temperature faster.

I doubt that the phosphor alone can account for the faster
warm-up time. It does not trap or reflect enough energy to
make any significant difference. I agree with Don that the
arc tubes in the two lamps must be different.

It would appear to, but I have done some measurements on two identical HPM
lamps and the results seem to validate the redirection hypothesis.

The lamps are the HQL 80W and the HQA 80W. The internal construction is
identical, as they are of exactly the same power. The HQL always warms up
faster.

Could it be that the UV components which exite the phosphor achieve
higher output first? That cause apparently faster run-up time in a
fluorescent lamp. You could detect this by seeing how the spectral
components ramp up relative to each other during run-up.
[/quote]
I cannot check that, so I cannot tell. However, there>s a dead-on giveaway,
which provides a sort of a super-clue for the redirection hypothesis:

I have measured the temps of both envelopes and the envelope of the HQL runs
hotter after warmup. This is the result of having more thermal radiation
produced there. Why is there more thermal at the phosphored glass envelope?
Because we have energy conversion there. UV -> Vis and apparently as a byproduct
of the previous, UV -> IR.

On a glass envelope there is still some thermal from absorption, but most of the
UV upwards of 350-365nm seems to escape.

The processes: UV -> Vis is not terribly efficient in this case, hence one
should get some extra heat there. Not very much, but perhaps enough to make the
envelope a heat radiator which aids the burner in reaching equilibrium faster.
--
I.N. Galidakis

TKM · Guest

"I.N. Galidakis" <morpheus@olympus.mons> wrote in message
news:1224866136.28434@athprx04...
[quote]Andrew Gabriel wrote:
In article <1224847316.246031@athprx04>,
"I.N. Galidakis" <morpheus@olympus.mons> writes:
Victor Roberts wrote:
On Mon, 29 Sep 2008 15:10:25 +0300, "I.N. Galidakis"
morpheus@olympus.mons> wrote:

Travis Evans wrote:
[snip]

Do phosphored mercury lamps have generally shorter warm-up times for
some reason, ...?

Yes, they do. The phosphor redirects some of the radiation back to the
burner and as a result the burner reaches optimal temperature faster.

I doubt that the phosphor alone can account for the faster
warm-up time. It does not trap or reflect enough energy to
make any significant difference. I agree with Don that the
arc tubes in the two lamps must be different.

It would appear to, but I have done some measurements on two identical
HPM
lamps and the results seem to validate the redirection hypothesis.

The lamps are the HQL 80W and the HQA 80W. The internal construction is
identical, as they are of exactly the same power. The HQL always warms
up
faster.

Could it be that the UV components which exite the phosphor achieve
higher output first? That cause apparently faster run-up time in a
fluorescent lamp. You could detect this by seeing how the spectral
components ramp up relative to each other during run-up.

I cannot check that, so I cannot tell. However, there>s a dead-on
giveaway,
which provides a sort of a super-clue for the redirection hypothesis:

I have measured the temps of both envelopes and the envelope of the HQL
runs
hotter after warmup. This is the result of having more thermal radiation
produced there. Why is there more thermal at the phosphored glass
envelope?
Because we have energy conversion there. UV -> Vis and apparently as a
byproduct
of the previous, UV -> IR.

On a glass envelope there is still some thermal from absorption, but most
of the
UV upwards of 350-365nm seems to escape.

The processes: UV -> Vis is not terribly efficient in this case, hence one
should get some extra heat there. Not very much, but perhaps enough to
make the
envelope a heat radiator which aids the burner in reaching equilibrium
faster.
--
I.N. Galidakis

[/quote]
Did you measure the lamp current vs. time as the lamps warmed up? Higher
current
earlier in the warm-up process would make the lamp warm up faster.

Terry McGowan

TKM · Guest

"Boxman" <boxman@voyager.net> wrote in message
news:b402bc95-bb38-4052-9321-9b2ebfc6f0bd@t54g2000hsg.googlegroups.com...
[quote]The linked article (basically a Press Release) describes microplasma
lighting. Anyone seen the actual product or any opinions on whether
this is viable?

http://www.marketwatch.com/news/story/eden-park-illumination-announces-new/story.aspx?guid=%7B84955B94-33E4-4014-92DC-D18F338A2D8F%7D&dist=hppr
[/quote]

Sounds like the Sylvania PLANON lamp. See:

http://www.sylvania.com/BusinessProducts/LightingForBusiness/Products/Lamps/PLANON/PlanonFAQs.htm

It>s been around for a while, but I>ve not seen any commercial luminaires or
installations.

Terry McGowan

I.N. Galidakis · Guest

TKM wrote:
[quote]"I.N. Galidakis" <morpheus@olympus.mons> wrote in message
news:1224866136.28434@athprx04...
Andrew Gabriel wrote:
In article <1224847316.246031@athprx04>,
"I.N. Galidakis" <morpheus@olympus.mons> writes:
Victor Roberts wrote:
On Mon, 29 Sep 2008 15:10:25 +0300, "I.N. Galidakis"
morpheus@olympus.mons> wrote:

Travis Evans wrote:
[snip]

Do phosphored mercury lamps have generally shorter warm-up times for
some reason, ...?

Yes, they do. The phosphor redirects some of the radiation back to the
burner and as a result the burner reaches optimal temperature faster.

I doubt that the phosphor alone can account for the faster
warm-up time. It does not trap or reflect enough energy to
make any significant difference. I agree with Don that the
arc tubes in the two lamps must be different.

It would appear to, but I have done some measurements on two identical
HPM
lamps and the results seem to validate the redirection hypothesis.

The lamps are the HQL 80W and the HQA 80W. The internal construction is
identical, as they are of exactly the same power. The HQL always warms
up
faster.

Could it be that the UV components which exite the phosphor achieve
higher output first? That cause apparently faster run-up time in a
fluorescent lamp. You could detect this by seeing how the spectral
components ramp up relative to each other during run-up.

I cannot check that, so I cannot tell. However, there>s a dead-on
giveaway,
which provides a sort of a super-clue for the redirection hypothesis:

I have measured the temps of both envelopes and the envelope of the HQL
runs
hotter after warmup. This is the result of having more thermal radiation
produced there. Why is there more thermal at the phosphored glass
envelope?
Because we have energy conversion there. UV -> Vis and apparently as a
byproduct
of the previous, UV -> IR.

On a glass envelope there is still some thermal from absorption, but most
of the
UV upwards of 350-365nm seems to escape.

The processes: UV -> Vis is not terribly efficient in this case, hence one
should get some extra heat there. Not very much, but perhaps enough to
make the
envelope a heat radiator which aids the burner in reaching equilibrium
faster.
--
I.N. Galidakis

Did you measure the lamp current vs. time as the lamps warmed up?
[/quote]
No.

[quote]Higher
current
earlier in the warm-up process would make the lamp warm up faster.
[/quote]
Of course it would. Imo, one way to interpret: "HQL warms up faster than HQA",
would be exactly that. That at some time t > t_0 = starting time, we have:

di(HQL)/dt > di(HQA)/dt

In other words, HQL>s current, rises faster to the current asymptote than HQA>s
current.

The question is WHY this happens with mechanically identical lamps and the same
ballast.

I stand by my explanation that the phosphored envelope acts as a heat reflector,
causing a feed-back loop mechanism, which gradually raises the burner
temperature "just a bit" higher than the corresponding temp of the clear lamp at
the same time, hence causing a very slight rise in the current.

Once equilibrium is reached, the additional heat doesn>t seem to have much of an
effect, because the ballast doesn>t allow the current to be raised further.

I think the rest follows, but feel free to shoot my explanation down :-)

[quote]Terry McGowan
--[/quote]
I.N. Galidakis

Don Klipstein · Guest

In <EmqMk.90851$Mh5.90546@bgtnsc04-news.ops.worldnet.att.net>, TKM wrote:
[quote]
"I.N. Galidakis" <morpheus@olympus.mons> wrote in message
news:1224866136.28434@athprx04...
Andrew Gabriel wrote:
In article <1224847316.246031@athprx04>,
"I.N. Galidakis" <morpheus@olympus.mons> writes:
Victor Roberts wrote:
On Mon, 29 Sep 2008 15:10:25 +0300, "I.N. Galidakis"
morpheus@olympus.mons> wrote:

Travis Evans wrote:
[snip]

Do phosphored mercury lamps have generally shorter warm-up times for
some reason, ...?

Yes, they do. The phosphor redirects some of the radiation back to the
burner and as a result the burner reaches optimal temperature faster.

I doubt that the phosphor alone can account for the faster
warm-up time. It does not trap or reflect enough energy to
make any significant difference. I agree with Don that the
arc tubes in the two lamps must be different.

It would appear to, but I have done some measurements on two identical
HPM
lamps and the results seem to validate the redirection hypothesis.

The lamps are the HQL 80W and the HQA 80W. The internal construction is
identical, as they are of exactly the same power. The HQL always warms
up
faster.

Could it be that the UV components which exite the phosphor achieve
higher output first? That cause apparently faster run-up time in a
fluorescent lamp. You could detect this by seeing how the spectral
components ramp up relative to each other during run-up.

I cannot check that, so I cannot tell. However, there>s a dead-on
giveaway,
which provides a sort of a super-clue for the redirection hypothesis:

I have measured the temps of both envelopes and the envelope of the HQL
runs
hotter after warmup. This is the result of having more thermal radiation
produced there. Why is there more thermal at the phosphored glass
envelope?
Because we have energy conversion there. UV -> Vis and apparently as a
byproduct
of the previous, UV -> IR.

On a glass envelope there is still some thermal from absorption, but most
of the
UV upwards of 350-365nm seems to escape.

The processes: UV -> Vis is not terribly efficient in this case, hence one
should get some extra heat there. Not very much, but perhaps enough to
make the
envelope a heat radiator which aids the burner in reaching equilibrium
faster.
--
I.N. Galidakis

Did you measure the lamp current vs. time as the lamps warmed up? Higher
current
earlier in the warm-up process would make the lamp warm up faster.
[/quote]
If the lamps are the same, and warmed up on the same ballast, what I
would check for is lamp voltage as a function of time. If lamp B is
actually warming up faster than lamp A, then the voltage across lamp B
will be increasing more rapidly. (The lamp voltage normally decreases
over the first few to several seconds and then increases.)

- Don Klipstein (don@misty.com)


www.GetXFactor.com Leading Technology, Science, Agriculture News and information	Part of the Identityscape.com network... getxfactor.com jmoodmusic.com smartbusinesschoices.com mintdepot.com lowfaresalways.com evangelicalview.com shoppingpodder.com soproudlywehail.com webnews.ws currenthumor.com

Science and Technology news... Forum Index -> Engineering - Lighting Forum	Goto page Previous 1, 2, 3 Next
Page 2 of 3