Thanks for the link. Interesting.
Should work assuming what’s presenting is accurate which for the most part sounds correct for its day in tech or understanding. Don’t put it on a 115v lamp, bump the
fixture or expect similar lamp life. (Read the entire thing and it was longer than my normal post.)
Except that for the most part low
voltage Stage & Studio and most quality architectural lamps do not have a problem with dimming these days, nor do they have a problem with series wired circuits in dimming. Minor detail in the low
voltage lamps of today are mostly improved and don’t have the dimming cited problem possibly if not by way of
filament improvements or gas changes by double
crimping the bases. Normally what happens in the case of a low
voltage lamp that’s dimmed is the same that happens with a moving light
HMI type lamp when not supplied proper
power to operate. The gasses within the lamp etch away at the coolest parts of the lamp - normally the pinch or fill pinch until they find a hole while operating at lower heat. On either lamp, if not burned too long on a
dimmer persay, they should function properly again for the most part with only slight loss. If burned for a time in such conditions there will be loss in
tungsten spent which will not come back and also stick to the walls of the lamp.
In the case of a low
voltage halogen filament lamp it’s noted that you can dim the lamp as normally only the
halogen gas will not get hot enough to re-deposit
tungsten on the
filament and instead such a lamp will act as per a normal
incandescent lamp. Once the spent particles of
tungsten are on the outer
globe of the
filament they tend to stay or stain there and could also reflect light in overheating the lamp to some extent as a concept though no doubt not to a large extent at the center hottest part of the
globe in light still getting out.
Unless the lamp has a
dichroic coating to it to boost it’s temperature while dimmed, the above older lamp
halogen gas within it might not get warm enough to operate on a low
voltage lamp (typically 64VAC or less is considered low
voltage.) Add that
dichroic coating on the other
hand and the lamp will either overheat or have a short lamp life. Only lamps I know of or believe I know of with a
dichroic coating is a DYS lamp and a few
PAR 36
ACL lamps most discontinued at this
point. All are 120v and their lamp life is very short indeed but
color temperature is on the other
hand very high. Don’t know of any low
voltage dichroic coated lamp capsules but again with the not designed for dimming when designed or most I think improved low
voltage lamps no longer have a large problem with dimming and need such a coating.
140VAC supply
voltage in design for 120v rated lamps for instance sounds nearly correct on the other
hand in the
design factor I remember for them and one would not want to be using a modern 115v lamp with such a contraption:
On the other
hand: The
effect of
voltage on the light output of a lamp is ±1%
voltage over the rated amount stamped on the lamp, gives 3.1/2% more light or Lumens output but decreases the life by 13% and vise a versa.
Do not operate quartz Projection lamps at over 110% of their design
voltage as rupture might occur. GE Projection, Ibid p13
(This might be for low
voltage lamps on the other
hand in me remembering a 140v for 120v lamps in general
line lamps. On the other
hand it could also be the case for
stage and studio type lamps.)
It would seem a 132V lamp would be more correct for a 120v stamped lamp and 140v is a wee
bit over the proper operating
voltage but possibly within
design factor margin (just don’t bump it.) On the other
hand if what they present about DC
voltage is correct, it could be absolutely correct that 140VDC is ok in concept in theory. (Moot
point as this
point given this is about
line voltage lamps and past technology.)
But to support this more or less if 140VDC is correct:
Voltage, A measurement of the electromotive force in an electrical
circuit or device expressed in volts.
Voltage can be thought of as being analogous to the pressure in a waterline. The
effect of
voltage on a lamp will cause a significant change in lamp performance. For any particular lamp, light output varies by a factor of 3.6 times and life varies inversely by a factor of 12 times any percentage variation in supply. For every 1% more in change in supply
voltage light output will rise by 3.6% and lamp life will be reduced by 12%. This applies to both DC and
AC current. Most standard
line voltage lamps are offered at 130v. Since most
line voltage power is applied at 120volts, the result is a slight under voltaging of the
filament. The
effect of this is substantially enhanced lifehours, protection from
voltage spikes and energy cost savings. - GE Spectrum Catalog ???
A 5% change in the
voltage applied to the lamp results in
-Halving or doubling the lamp life
-a 15% change in luminous flux
-an 8% change in
power
-a 3% change in
current
-a 2% change in
color temperature (0.4% change per1%
voltage.)
Osram Technology and Application
Tungsten halogen Low
Voltage Lamps Photo Optics, p.21
Note the 0.4% change in
color temperature per 1% of
voltage applied to it as a figure while both references above a by far different in scope of change when
voltage is involved. (Also that GE says that it don’t matter if AC or DC
power)
A
filament lamp depending on what
manual is referenced is somewhere between 3,500°K and 3,655°K as a absolute maximum. After that
color temperature the
filament melts down in being related to heat. Consider a
voltage spike or higher than 120v supply
power in this. The closer to that higher
color temperature you get, the shorter the lamp life no matter how much you as per a three legged chair say reduce luminous output (if possible) to compensate for retaining some lamp life given an amperage. This in adjusting the doping (mixture of metals) in the
filament for more
color temperature, lamp life but less output.
From both GE Spectrum and Osram lamp manuals also:
Tungsten filaments change electrical energy to radiant energy. The light generated results from the
filament being resistance heated to a temperature high enough to produce visible light. Filaments can not be operated in air see seal and vacuum.
Tungsten is used for the filaments because of its low rate of evaporation at temperatures of
incandescence and its high melting
point 3,655°K. There are grades of
tungsten purity and different grain structures. Only the highest grade of an elongated grain structure guarantees maximum life and reliability during
shock and vibration. Heat treatment of the
tungsten filaments is one of the most critical factors in lamp manufacturing.. Proper heat treatment prevents
filament sag, abnormal coil shorting or premature breakage. (GE Spectrum)
Halogen Lamps are
tungsten fliament
incandescent lamps filled with an inert gas (usually krypton or xenon to insulate the
filament and decrease heat losses) to which a
trace of
halogen vapor (bromine) has been added.
Tungsten vaporized from the
filament wire is intercepted by the
halogen gas before it reaches the wall of the
bulb, and is returned to the
filament. Therefore, the glass
bulb stays clean and the light output remains constant over the entire life of the lamp. (p33, Sylvania Lamp &
Ballast Product Catalog 2002)
On the other
hand I would be suspicious of their 140VDC improved lamp life statistics and or sampling
profile given these points:
First simply put, the
halogen effect redeposits spent particles of
tungsten onto the hottest part of the
filament as carried by the gasses in circulating during the heating/cooling process. If DC powered, the center of the
filament is no longer the hottest part of the
resistor, it’s the first segment of that
filament would now be hottest which would get most of the redeposit. Some obviously would get spread across the
filament if hot enough to produce light but it just as with AC lamps they normally fail from the ends, it should be the same case here based on depositing the
tungsten onto the hottest part of the lamp. The
return side of the
filament would not get an equal depositing of
tungsten on it and tend to wear quicker than the hot side in failing at times especially with
shock than a standard AC lamp. Such lamps could with a bump get thrown out of a test sample in being more than the 10% of the sampling given they were bumped, or given bench testing not be seen in sufficient quantities to
effect the sampling.
This and the below that’s probably related:
I believe this is from the GE Spectrum or Low
Voltage Lamp Catalogue -
DC
voltage can reduce life by approximately 50% to 70% due to the “sawtooth” or notching
effect. Notching, also known as electromigration, is a change in the molecular structure of
tungsten due to the DC
voltage. The results are hot spots that accelerate the thermal conditions, the evaporation rate and embrittlement. DC
voltage operation is not recommended for
filament lamps.
Also, I believe from the same reference about
shock and vibration:
The best
filament design for use in a
shock and vibration environment is a low
voltage, high amperage
filament. This represents a short, thick
filament. The higher you go in
voltage, the longer the
filament, which then necessitates the use of hangers. The hangers will increase the higher
voltage filament reliability, but the effects of notching due to the soret
effect are increased. Orientation of the
filament in relationship to the axis of vibration will also affect the lamp performance in a
shock and vibration environment. The most critical consideration in protecting a lamp against the effects of
shock and vibration is the packaging by the user.
Filament damage, due to
shock and vibration, can be reduces or amplified by the way the lamp has been assembled into the user’s product.
So in theory the DC
voltage supply
voltage booster should work fine as a concept in theory. That that it is is not currently still made or copied probably says on the other
hand that it worked as a concept but bump the
fixture and or you get in general more lamp failures in general. Not sure about improving the efficiency of the lamp for other than a short period of time but they do say that the lamp won’t last as long so that’s probably accurate. Not gonna blow up and probably the lamps should last a production or two but in optimizing output if this does it you do not optimize the dependability or lamp life. If big budget for lamp replacement and needing to go to “11" for output, sure this might help assuming you could not go higher in wattage or lamp down the show to have that higher wattage ceiling and after that if needed color correct.
