3.1.2 Variation in supply voltage for adapted inductance. Osram HQI-E 150 W/NDL CL
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3.1.2 Variation in supply voltage for adapted inductance
Some countries have supply voltages that permanently deviate from 230V. When using correspondingly adapted inductances, the following points must be taken into account.
3.1.2.1 Operation at supply voltage higher than 230 V with adapted choke impedance
An increase in supply voltage shifts the maximum of the choke characteristic curve (P
L over U
L
/U
N
). In the lamp voltage range of OSRAM lamps (approx. 100 V), the change in lamp wattage with changing lamp voltage is steeper. In addition, the maximum wattage that can be achieved with increasing lamp voltage is larger, as shown in Fig. 9. Normally, the lamp voltage increases with increasing service life (see also chapter 6
“Lamp service life, aging and failure behavior”).
120
100
80
60
200
180
160
140
40
20
0
0
3
2,5
2
1,5
1
0,5
0,5
U /U
S
1
0
Fig. 9: Lamp current I
L
, lamp wattage P
L over the ratio of lamp voltage to supply voltage U
L
/U
S
for U
S
=277 V
3.1.2.2 Operation at supply voltage less than 230 V with adapted choke impedance
According to equation Eq. 4.1, wattage of about 150 W is achieved for a 150 W choke with a lamp voltage of
100 V. The maximum the lamp wattage can increase to for a lamp voltage of 150 V is 175 W. The higher achievable wattage can reduce the service life and possibly cause an increase of undesirable effects at the end of the service life (e.g. lamp explosion).
Supply voltages of less than 230 V shift the maximum of the choke curve (P
L over U
L
/U
S
). Operation at 200 V supply voltage for example is more favorable than at
230 V with regard to the change in lamp wattage with lamp voltage. The P
L
(U
L
) curve runs fl atter in the normal range of lamp voltage. For lamp voltages exceeding
130 V Wattage falls again.
OSRAM lamps are generally designed to operate at
230 V supply voltage and undergo corresponding service life testing. There are, however, also systems at
400 V, e.g. for some discharge lamps > 1000 W. For these lamps, the following explanations apply in the same way. The use of high intensity discharge lamps is theoretically also possible at 277 V operating voltage with adapted impedance and ignition devices, although such operation is associated with considerable disadvantages.
120
100
80
60
200
180
160
140
40
20
0
0 0,5
U /U
S
3
2,5
2
1,5
1
0,5
1
0 a) An increase in negative effects must be expected at the end of the service life, because wattage rises clearly above the nominal wattage when lamp voltage increases on account of the shifted choke characteristic curve. The increased wattage input for lamps with already aged arc tube wall can cause increased lamp explosion rates, for example. Operation in overload conditions will probably cause accelerated aging.
b) The steeper characteristic P
L
(U
L
) in the range of the normal lamp voltage causes a higher spread of the wattage and therefore of the photometric data, e.g. perceived colour variation.
Fig. 10: Lamp current I
L
, lamp wattage P
L
over the ratio of lamp voltage to supply voltage U
L
/U
S
at U
N
=200 V
There is a major drawback that with lower supply voltage, there is also less voltage available for re-ignition after the current has passed zero crossing. If the momentary supply voltage is lower than the re-ignition voltage, the lamp goes off. Normally, the lamp voltage and also the re-ignition peak increase with increasing service life (see also chapter 6, “Lamp service life, aging and failure behavior”). That means that a reduction in supply voltage causes a shorter service life in many lamps.
We therefore discourage operating the lamps at 277 V supply voltage. Our lamps have been developed and undergone service life testing at 230 V supply voltage, so that we cannot assume any warranty for the service life behavior and photometric data for any deviating operation.
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