Philips Electromagnetic Lamp manual 134, Gear, Luminaires, Maximum temperatures Lamps

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3.12 Ambient and operating temperatures

Once ignited, the lamp warms up its surroundings and, after run-up, the low ambient temperature has less influence on the electrical performance. Still, the light output varies with the actual tube wall temperature. Capacitive circuits give less light at low temperatures than inductive circuits due to the constant-current characteristic of the capacitive circuit.

2) Gear

The minimum temperature for some electronic components and for compensating capacitors is -25 ºC.The capacitance of capacitors, for instance, declines steeply below that temperature. For that reason gear should be installed at places where the ambient temperature will not fall below -25 ºC.

3) Luminaires

In general the construction of the luminaires and optics is not affected by low ambient temperatures down to -25 ºC. Of course plastic parts such as clips are more brittle at low temperatures and should then be handled with care.

Maximum temperatures

1) Lamps

For fluorescent lamps the temperature of the glass tube wall is of prime importance, especially with regard to the applied phosphors. It will be clear that the actual lamp temperature very much depends on the luminaire in which the lamps are placed. Lamps must only be used in luminaires which are constructed for that particular type of lamp. For some lamp types absolute maximum temperatures of a specified spot are given (see SL, Fig. 128).With this in mind, also see maximum and ambient temperatures under point 3) Luminaires.

Fig. 128. The maximum recommended ambient temperature at which an SL lamp can operate is 55 ºC . The part of the lamp with the highest temperature is a 5 mm wide section around the circumference of the housing. The temperature measured in this region, on the surface of the housing, is about 150 ºC . Exceeding this temperature can result in reduction of lamp life.

5 mm

warmest region of the housing

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