OSRAM PrevaLED Core Z2 - Manual (Page 20)

20
THERMAL CONSIDERATIONS
The thermal test engine (TTE) for the determination
of thermal resistance:
With the TTE according to Zhaga specifi cation, the intro-
duction of the heat output into an existing luminaire can
be simulated. To do so, the following work steps need to
be taken:
1. Installation of the TTE with thermal interface material
(TIM) into the luminaire prototype to be measured
2. Introduction of different heat outputs P
TTE
(e.g. in 10-W steps)
3. Measurement of the reference temperature t
r, TTE
after temperature stabilization, by means of the
thermo couple attached in the TTE
4. Thermal resistance calculation
5. Draw the graph of R
th, lum
dependent on P
TTE
, as shown in
the diagram
Choosing the suitable module:
The datasheet shows heat output values of the module
(P
th, mod
) for all versions of the PrevaLED ® Core Z2 as well as
the maximum permissible thermal resistances (R
th, mod, max
).
Two examples are shown in the diagram. The datasheet
values are specifi ed for t
a
= 25 °C, in case of a differing
ambient temperature t
a
’, the corresponding R
th, mod, max
can
be calculated according to the following formula:
All modules of which the data points are located on or
above the curve are suitable for application in the luminaire.
In the example shown in the illustration above, LEP-1500-
835-Z2 is suitable for application in both luminaires,
whereas LEP-2000-835-Z2 is suitable for luminaire 2 only.
Although suitable modules can be easily and clearly
determined with this method, we nevertheless recommend
verifying the thermal design by means of measurements
with real modules, as outlined in
chapter 4.3 .
The TTE serves the thermal measurement of an existing
cooling method or housing.
By means of their maximum cooling performance [W] as
based on T
c
max. [°C], it is therefore easily possible even
in the future to equip once thermally measured luminaires
with standardized light engines.
R
th, lum
=
t
r, TTE
-t
a
P
TTE
R
th, mod, max (ta')
= R
th, mod, max (25 °C)
-
t
a
'- 25 °C
P
th, mod
Additionally, a simple thermal ECG dummy can be used
for the simulation of the thermal power loss in the appli-
cation (simulation of additional heat input, e.g. in case of
suspended ceilings).
Thermal OTp tester
TTE engineering drawing at: www.osram.com/prevaled-core