Manufacturer: | Philips |
Model: | Mastercolour CDM-T 35W/830 |
Primary Application: | Display lighting. |
Ballast Type: | Philips MHC 035 S/50 |
Wattage: | 35W |
Diameter (max): | 18mm |
Length: | 100mm |
Electrode gap: | 5mm |
Bulb/Tube material: | Outer: UV-Stop Quartz. Inner: ceramic |
Colour Temperature: | 3000°K |
Peak output wavelength: | N/A - Broadband emission. |
Total light output: | 3300Lm |
Rated lifetime: | 12'000 Hours. |
Cap: | G12 |
Operating voltage: | 90V |
Striking voltage: | 5KV Max |
Operating current: | 0.85A |
Warmup/restrike time: | 3 minutes/15 minutes maximum. |
Cost (original): | Unknown |
Value (now): | Unknown |
Place of manufacture: | Belgium |
Date of manufacture: | July 1999 |
Notes: | The use of ceramics in metal halide lamp construction
has long been recognised as having many advantages - namely that it is
more resistant to chemical attack by the halide salts present within
the lamp, and that it is able to withstand higher temperatures than the
equivalent quartz structure. The greater corrosion resistance
also allowed adequate lifetimes to be reached without requiring as
thick (and heavy) a wall on the arc tube. This meant that ceramic
arc tubes had a smaller thermal mass, allowing lamps to run up/re-strike
more rapidly than their quarts equivalents. It was not a design
without at least some problems to overcome however - not least figuring
out how to get a metallic conductor into the ceramic arc tube to carry
the discharge. The conventional metals for doing this (usually
niobium, such as found in the similar arc tubes used in high pressure
sodium lamps) can not be used, as they are rapidly attached by the
halide salts at the operating temperatures of the arc tube.
Philips however were the first to come up with a truly practical
solution, which resulted in the launch of their CDM range of lamps in
1994. The design was so successful that 15 years on, virtually
all ceramic metal halide lamps are still using arc tubes in some way
based on the Philips CDM design. The key to this success was to
move the fragile seals as far away from the intense heat of the arc as
possible, therefore reducing their temperature and as a result the rate
of attack. The very long seal region also allows the seal to be
made of conventional niobium wire tucked away in a thin enough tube
that the halide salts cannot diffuse towards the seal reasons.
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