OSRAM POWERTRONIC PT-FIT I ECG for HID lamps, with cable clamp - Manual (Page 22)

THE PRODUCT IN OPERATION
2.3.7. General hints on installation in relation to
temperature
It is essential to ensure that lamp and ECG do not heat up
each other in the luminaire and that the ECG power loss
can be safely dissipated even at the maximum expected
ambient temperatures and/or supply voltage.
The temperature at the t
c
test point of the ECG may not be
exceeded even at the maximum expected ambient tempe-
rature and/or supply voltage. When measuring temperatu-
res under "normal" operating conditions at the t
c
test point
a temperature should be obtained that is at least 5 to
10 °C below the maximum value indicated, in order to be
sure of enough safety buffer for extreme situations.
To achieve an optimal temperature situation it may be ne-
cessary to decouple the system (e.g. putting the lamp in
the luminaire head and the ECG in the base or light sup-
port) as the lamp and ECG will always warm each other
up if positioned too close together, leading to excessive
temperatures in the ECG. Such a separation of the parts
of the system must respect the maximum permissible
cable lengths between ECG and lamp(s).
→ See also wiring notes (Section 2.2.4)
→ See also the notes on luminaire structure and thermal
coupling (Sections 2.4 and 2.4.1)
2.3.7.1. Power reduction control due to overtemperature
It may occur that, due to suboptimal luminaire construc-
tion or by external heat sources (e.g. direct sunlight), an
ECG may operate at a too high temperature; i.e. at a tem-
perature outside the specifi ed range. In order to protect
the device from damage, the POWERTRONIC
® will auto-
matically reduce the output wattage. This reduction has
the same effect as relieving the thermal load of the device
and should protect it from irreversible damage. The reduc-
tion is limited to a maximum of 40 % of the nominal wattage.
Once the device is back within the specifi ed temperature
range the wattage is reset. Users will notice any such
power reduction control through a reduction in the luminous
fl ux of the affected lamps. If this is not suffi cient the ECG
will shut down to protect itself.
Power reduction control due to overtemperature is the
"last exit" before the shutdown or destruction of the
device. For this reason when designing luminaires, one
should be careful that there are enough thermal reserves
for the ECG at normal ambient temperatures and that the
device is not already operating close to the limits.
Permanent power reduction with negative effect on light
quality, on effi ciency and possibly even on the service life
of the lamp, as well as frequent shutdown or premature
aging and failure of the ECG will be logical consequences
in such cases.
22
2.3.7.2. ECG temperature measurement in the luminaire
According to EN 60598-1 there are precisely defi ned test
and measurement preconditions both for surface-mounted
luminaires (fi xed: e.g. downlights, and portable ones: e.g.
free-standing luminaires) and for recessed luminaires.
The relevant temperatures of the ECG (at the t
c
test point)
can be best determined using stick-on thermocouples or
using a suitable measurement device. You must make sure
that the adhesive/glue is thermally neutral.
For ECG measurement it is generally suffi cient to equip
the casing cover with a thermocouple. The temperature
values should only be determined when the steady state
temperature of the system has been reached; i.e. when no
signifi cant change in temperature occurs over a longer period.
In accordance with the standards, this measurement
should be done at the highest value of the rated voltage
range. It makes sense, however, to get the measurements
at the most unfavorable voltage in the rated voltage range,
which is generally the lower limit of the range, since this
voltage will require the highest current and thus the heavi-
est possible thermal load.
When assessing the thermal properties of the luminaire it
is recommended to use the following procedure for the
measuring system specifi ed in EN 60598-1:
1. Thermal situation in the luminaire without any heating
by the control gear.
Luminaire in measuring system according to EN 60598-1
in nominal mounting position equipped with lamp con-
nected to ECG and thermal elements. How ever, the
lamp is not operated by the built-in ECG, but by an
externally wired control gear. In this way it is possible to
determine only the heat generated by the lamp on the
whole system and to optimize the thermal "coupling" to
the environment.
2. Thermal situation in the luminaire including warming by
the control gear.
Arrangement as described in point 1, but with the lamp
being supplied by the built-in control gear. Taking the
previously obtained values into account the additional
heating generated by the ECG can now be determined.