Equipment: Lamps and Gear - Road Lighting: Fundamentals, Technology and Application - page 122

500

830 840

400

300

200

100

0

400 450 500 550 600 650 700 400 450 500 550 600 650 700

ʻ (nm) ʻ (nm)

Fig. 10.10 Spectral power distributions of a compact fluorescent lamps with colour types 830 and
840

System Efficacy The higher-wattage versions, which are most suited for street
lighting, reach efficacies up to some 70 lm/W.

Lifetime Non-integrated CFLs have lifetimes, based on L 20 between 7000 and
20,000 h, with the better values for the higher wattages.

Run-Up and Re-ignition Fluorescent lamps operated om present-day electronic
gear start within 1.5 s and without flickering. When a hot lamp is switched off, the
vapour pressure drops so quickly that re-ignition is instantaneous.

Dimming Non-integrated compact fluorescent lamps with four-pin lamp cap can be
dimmed.

Ambient-Temperature Sensitivity The luminous flux of a fluorescent lamp is de-
termined by the mercury vapour pressure during operation. The mercury vapour
pressure is in turn determined by the coldest spot in the tube, which, because fluo-
rescent lamps have no outer bulb, is dependent on the ambient temperature. With a
compact lamp the coldest spot is also dependent on its tube shape. In all cases the
luminous efficacy decreases with temperatures lower than some 20-30 ⓦ C ambient
temperature. In completely-open luminaires, at 10 ⓦ , the remaining light output

may be lower than 20 % of the nominal value. So, in colder regions, fluorescent
lamps should never be used in open luminaires.

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10.2.6 Induction Lamps

Induction lamps, like fluorescent lamps, belong to the family of low-pressure mercury
gas-discharge lamps. Unlike other discharge lamps they have no electrodes, which
is why they are also called “electrodeless lamps”. The consequence of having no
electrodes is a very long economic life of around 60,000-75,000 h. This long life is
also the main feature of induction lamps. They find their application in situations