OSRAM POWERTRONIC PT-FIT I ECG for HID lamps, with cable clamp - Manual (Page 19)

THE PRODUCT IN OPERATION
19
2.3.6.1. Device temperature t
c
According to EN 60598-1 t
c
(temperature casing) is the
highest permissible temperature that may occur during
normal operation under the nominal voltage (or at the
maximum value of a rated voltage range) on a particular
marked point of the ECG (the t
c
test point). It is thus
a safety-relevant value.
In practice, the temperature measured at the t
c
test point
of the ECG will depend on a variety of factors:
• The ambient temperature of luminaire
• Losses and the resulting self-heating of the ECG
• Luminaire design and the thermal coupling of the ECG
to the luminaire
In order to determine the life expectancy of an ECG, the
temperature of the ECG at the t
c
measuring point is com-
pared against the values that appear on the datasheet.
In order to reach the life expectancy that is reported in
the datasheet, the t
c
should never be exceeded.
It is possible for each ECG manufacturer to position the t
c
test point where he or she likes on the ECG. It may be
placed at a particularly hot point or at a cooler point, and
thus has a direct infl uence on the real temperature mea-
sured for the device.
For OSRAM POWERTRONIC ® ECGs the t
c
point is always
positioned so that there is a good correlation between the
temperature measured at the t
c
point and the real tempe-
ratures of the components decisive for the life expectancy
of the ECG.
It should be pointed out that the absolute value of the
t
c
value represents no indication of quality, as it is me-
rely an individually placed test point used as described
above for the measurement of the t
c
value.
2.3.6.2. Ambient temperature t
a
of ECG
According to EN 60598-1 t
a
(a=ambient) is the highest val-
ue of continuous temperature at which the luminaire (or
ECG) may be operated appropriately. That means that this
temperature may not exceed the t
c
temperature described
in section 2.3.6.1.
In the case of OSRAM POWERTRONIC
® ECGs, the speci-
fi ed maximum value for t
a
has a correlation with the value
for t
c
. This relationship applies to a reference measuring
system in accordance with EN 61347-1 Annex D. In it the
ECG is operated without any thermal connection to the
luminaire.
As the ECG ambient temperature t
a
is determined
under the reference conditions for all ECGs, it is also
suitable for making a direct comparison of the thermal
properties of different ECGs.
It is therefore possible to compare ECGs using the t
a
tem-
perature, even where there is no other means of compa-
ring them directly.
In practice the method used for the thermal design of lu-
minaires and for predicting the service life of an ECG in-
side a luminaire is measuring the t
c
temperature. However,
in this context the details on expected service life must
always be decided on the basis of the t
c
temperature for
each ECG separately.
Where ECG ambient temperatures (t
a
) are too low, then
the ECG is not capable of ensuring reliable lamp ignition.
In addition to this, at excessively low temperatures the
properties of particular parts may change to such an
extent that it leads to the failure of the ECG.
The ambient temperature should never fall below the
minimum t
a
marked on the ECG.
Where ECG ambient temperatures (t
a
) are too high the
service life of the ECG may be foreshortened or the ECG
may be destroyed. High ECG failure rates may occur.
Typical values for the storage of electronic control gear are
the following:
Storage temperature: -40 °C to max. +80 °C
Air humidity: 5 % to max. 85 %, uncondensed
It should be noted that:
Before these devices are put into service they must be
re stored to the specifi ed boundary temperatures for t
a
.
The values for t
a
temperatures for each device can be ob-
tained from the technical datasheet of the specifi c device.
2.3.6.3. ECG self-heating
POWERTRONIC
® ECGs have an effi ciency of 90 to 92 %.
The remaining wattage is lost energy which causes the
self-heating of the devices. Typical values for the increase
in temperature of ECG casings as compared to ambient
temperature are between 10 and 30 °C. This allows for a
very wide range of ambient temperatures within the rele-
vant limits, which will be quite suffi cient for the most
common areas of application. In cases where this is not
true, the thermal properties of the luminaire need to be
improved by making changes to the luminaire or to the
installation position.