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What kind of lamps are these?

Hello all!

The BBC has a photo of the lighting inside the Great Westminster Clock
(the clock that contains the bell "Big Ben"). I am curious as to what
type of lamps these are.

http://news.bbc.co.uk/1/shared/spl/hi/pop_ups/07/in_pictures_the_great_westminster_clock/html/8.stm

My first guess is some kind of "compact fluorescent" but with an
external ballast, but I don't really think the visible bulbs have the
usual thing fluorescent tubes folded up inside them. My next guess is
some kind of discharge lamp (mercury vapor or similar) - but those
usually have clear glass. The ballasts are clearly by Philips and seem
to plug into a standard UK socket (240 V, 50 Hz).

Thanks!

Matt Roberds
 
A

Andrew Gabriel

Jan 1, 1970
0
Hello all!

The BBC has a photo of the lighting inside the Great Westminster Clock
(the clock that contains the bell "Big Ben"). I am curious as to what
type of lamps these are.

http://news.bbc.co.uk/1/shared/spl/hi/pop_ups/07/in_pictures_the_great_westminster_clock/html/8.stm

My first guess is some kind of "compact fluorescent" but with an
external ballast, but I don't really think the visible bulbs have the
usual thing fluorescent tubes folded up inside them. My next guess is
some kind of discharge lamp (mercury vapor or similar) - but those
usually have clear glass. The ballasts are clearly by Philips and seem
to plug into a standard UK socket (240 V, 50 Hz).

This is quite well known as one of the first prestiege installations
of Philips QL lamps, so they're electrodeless induction fluorescent
lamps.

http://www.lighting.philips.com/gl_...&parent=4390&id=gl_en_feature_stories&lang=en
 
J

JB

Jan 1, 1970
0
The cost is a real sticking point with many of our customers. Many of them
look at short-term outlay rather than at through-life costs (where the
induction lamps _really_ score). Equivalent CFL lamps would need replacing
many times in 60k burning hours and the labour to change the lamps is an
additional significant cost with current labour rates and hire prices for
access equipment.
It's a range of issues. Cost is certainly one of them. Certainly as
a designer, I wouldn't specify them without good reason for cost.
Part of the cost is that the manufacturing standards of any extremely
long life lamp have to be excellent so that inconsistencies don't
shorten the life (the electrode is only one potential point of
failure). Economies of scale are an issue.

The QL is about the same size as a larger CFL, but the Icetron Enduras
are huge - there's no packing small reflectors around them. That's a
factor.
From a lamp engineer and luminaire designer's viewpoint, I would say that
the lumen output even of the 165W QL and the 150W Endura/Icetron is too low
for industrial/architectural/retail luminaires mounted at 6M+ (where
maintenance costs are prohibitively expensive). Even with a well designed
optical system, LORs of >80% are very hard to achieve, especially with the
Endura, so many more luminaires would be needed for a given illuminance
compared with an HID based scheme.

Ideally I'd want a minimum of 20k lumens and preferably >35k lumens to
enable a one-for-one replacement luminaire with conventional 250/400W metal
halide Hibays/Refractors. Sadly the QL system is pretty much at its maximum
performance levels with the 165W, although the Endura lamp design is
theoretically scaelable to several hundreds of watts. Some Chinese
manufacturers have produced 200W 'QL' types but I cannot confirm published
performance. Another downside is the lack of dimmable control gear for these
lamps. More than 40% of our larger projects now demand lighting control in
some form or another.

Despite these issues, these induction lamps remain some of my favourite
light sources to work with.


JB
 
V

Victor Roberts

Jan 1, 1970
0
It's a range of issues. Cost is certainly one of them. Certainly as
a designer, I wouldn't specify them without good reason for cost.
Part of the cost is that the manufacturing standards of any extremely
long life lamp have to be excellent so that inconsistencies don't
shorten the life (the electrode is only one potential point of
failure). Economies of scale are an issue.

The QL is about the same size as a larger CFL, but the Icetron Enduras
are huge - there's no packing small reflectors around them. That's a
factor.

I'd be interested in the views of the lamp engineers on the group.

I'd say that cost is the major issue. The cost is high due
to small volume production, the external ballast and the
extra shielding required for an RF lamp and ballast. I
disagree that these lamps require any higher manufacturing
standards, Just removing the electrodes provides the
required life improvements, as long as you are already using
a high quality phosphor.

--
Vic Roberts
http://www.RobertsResearchInc.com
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