rf light sources

A Technical Seminar On

RF light sources

Rakesh MandiyaRakesh.yadav1211@gmail.comDelhi Technological University

INTRODUCTION

RF light sources follow the same principles of converting electrical power into visible radiation as conventional gas discharge lamps.

The fundamental difference between RF lamps and conventional lamps is that RF lamps operate without electrodes.

RF LIGHTING

RF lamps, appeared about 100years ago, a half century before the basic principles lighting technology based on gas discharge had been developed.

DISCHARGE TYPES

Capacitive RF Discharge Inductive RF Discharge Wave –Sustained Discharges

Capacitive RF Discharge

The voltage applied to the lamp is mainly dropped in the sheaths.

Inductive RF Discharge

power transfer efficiency = Pp/(Pp+Pc)

operate over a wide range of gas pressure and frequency for which L.

CHOICE OF FREQUENCY AND DISCHARGE TYPE the frequency rage between 2.2 – 3.0

MHz (2.65MHz is standard) has reduced restrictions on EMI.

For frequencies at a few tens of kilohertz., generator efficiency is rather high.

COMMERCIAL RF LIGHT SOURCES

Microwave- Powered Sulphur Lamps Spherical External- Coil Induction Lamp Re-entrant Cavity Induction Lamp Self- Ballasted Re-entrant Cavity Lamp Low- Frequency Extended-coil Induction

Lamp

Microwave- Powered Sulphur Lamps

life rating of 15,000 hr.

low infrared and ultraviolet emission

good colour stability

SPHERICAL EXTERNAL- COIL INDUCTION LAMP

induction coil wrapped around the lamp

screen cage surrounds the lamp

operate at 27 W

efficiency is 37 lm/W

RE-ENTRANT CAVITY INDUCTION LAMP

operating at 2.65MHz

available in three wattages –55W, 85W,and 165W

shaped standard incandescent lamps

100,000-hr average rated life

SELF- BALLASTED RE-ENTRANT CAVITY LAMP

lamp power is 23 W at 48 lm/W

operating at 2.65 MHz

lamp life is rated up to 15,000 hours

LOW- FREQUENCY EXTENTED-COIL INDUCTION LAMP

consist of a 5.4 cm diameter Pyrex glass tube

operating frequency of 250 kHz

minimizes the problems associated with EMI

ballast design is much simpler than an RF system working at 2.65MHz

ADVANTAGES Absence of electrodes. Maintenance is low. Gas pressure is optimized for

maximal efficiency in RF lamps. It have instant and harmless

starting. Efficiency is high.

DISADVATAGES Cost is higher than fluorescent lamps. With increasing frequency, efficiency

will decrease, It is woks efficiently for some particular

frequencies, if frequency changes there are problems with electromagnetic interference (EMI).

FUTURE SCOPE

Induction lighting is an economical choice for many plants.

Induction lamps are suitable for a range of installations, including general lighting within a plant, as well as out door areas.

CONCLUSION

The elimination of electrodes opens up great opportunity for increased durability, light output and efficiency.

It removes many of the lamp-shape restrictions of conventional electrode discharge lamps .