Philips QL Induction Lighting Systems - Philips Lighting

4. Lamp operation
4.1 Starting characteristics
4.1.1 Ignition and lifetime performance
QL lamp systems offer direct, flicker-free ignition after
switch-on, in both cold and hot conditions.
Ignition time:
< 0.5 s
Hot-restrike time: < 0.5 s
Minimum HF generator test-point temperature for ignition:
-25°C/-13°F.
4.1.2 Luminous flux during starting period
The run-up behavior of QL lamp systems is influenced by:
- Luminaire construction.
- Ambient temperature at the moment of ignition.
- The duration of the period that the system was cooldowned
after the last switch-off.
The QL lamp systems are based on the low-pressure
mercury discharge technology and therefore in principle
sensitive to (changes in) ambient temperatures. This means
that after switch-on the light output of the lamp will vary until
a stable situation is reached, which depends on the actual
operating conditions. This will not happen in seconds but in
minutes.
If a lamp has reached the stable level and is switched on
again after a short off period, light output will immediately
return to around the normal stable level (incandescent lamplike).
4.1.3 Lumen maintenance
The luminous flux of a QL lamp system is expected to have
depreciated after 60,000 hrs to no less than 75% of the initial
flux (see figure 20 for a lumen maintenance curve).
Light (%)
QL 85W/840 maintenance
110
105
100
95
90
85
80
75
70
0 10000 20000 30000 40000 50000 60000
Life (h)
Figure 20: Lumen maintenance curve
4.2 Burning position
Although the burning position is universal, the relation
between light output and temperature will be different for
different burning positions. In the base-up position of the QL
lamp system, the amalgam temperature will be slightly
higher than in the base-down position with the same
environmental conditions. This phenomenon can be used in
luminaire design for specific ambient temperatures. As an
example, the shift of the luminous flux curve for a typical
design is given in figure 21.
Figure 21: Typical influence of burning position on luminous
flux
4.3 Optical design
QL lamp systems offer a homogeneous light distribution, and
can be used in a variety of luminaire designs. The choice of
material, shape and dimensions can help ensure optimum
functioning of the lamp (mechanically, thermally and
photometrically). If a lot of light is reflected back to the lamp,
this will increase the lamp operating temperature and may
result in lower light output. The reason for this is that the
main amalgam temperature will increase, which in turn
regulates the light output. For the same reason, it is advised
to keep the lamp cap behind the reflector (if used), because
the main amalgam is located in the lamp cap (see figure 22).
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