GE SHOWBIZ - Manual (Page 54)

GE LIGHTING - SHOWBIZ™ ENTERTAINMENT LIGHTING CATALOGUE 102
Arc Prevention in Tungsten Halogen Studio Lamp Applications
Almost all production personnel in the film and television industry have at some time encountered sudden
failure of incandescent studio lamps. When this occurs at a crucial moment and forces a re-shoot the cost
can be considerable.
The significant features of these failures were that they almost always occurred during the first 20 hours of
use and the incidence of failure increased with operating temperatures. Failure invariably resulted from an
arc across the filament plugs which destroyed the tails of the filament.
Tungsten halogen lamps are gas filled. The introduction of hydrogen is predicted to react with the halogen
to ‘slow down’ the tungsten halogen cycle. In addition it is known that hydrogen will slowly diffuse through
the hot quartz bulb so that the hydrogen concentration would gradually diminish.
The rate of loss of hydrogen during lamp operation is less than previously predicted and based upon
spectraradiometer measurements and calculations, maximum protection is only required during the initial
50 hours of life. Hence the use of hydrogen additions is the most advantageous method of ensuring reliable
operation of lamps during early life, particularly in demanding operating conditions.
GE Lighting offer lamps with proprietary hydrogen addition*.This offers adequate arcing
protection without significantly interfering with the halogen cycle.
GE LIGHTING - SHOWBIZ™ ENTERTAINMENT LIGHTING CATALOGUE 103
Lamp performance as a function of operating voltage
Tungsten halogen lamp performance (light output, power consumption, life, colour, temperature) is a
strong function of operating voltage. The rated performances claimed in this catalogue have been
achieved at nominal rated volts. Operating the lamps at other than the rated voltage will
significantly affect performance, as shown graphically on pages 106 and 107. All lamps are
designed for use with proprietary dimming equipment as required.
*owned by GE under US PAT #4743802