Основы светотехники на английском языке, страница 7

2000 h depending on the lamp type•Light colour:similar to daylight•Start current:up to 1.5 times the rated currentXenon high-pressure lamps are used for film and slide projectors as well as for signal and warning lights.1.4.6Neon tubesNeon tubes are gas-filled, glass tubes with unheated electrodes fitted to the ends. Unlike the fluorescentlamps, they need high voltage for ignition and operation. Stray field transformers provide the high ignitionvoltage and limit the current during operation like the chokes in the fluorescent lamp. The power factorwhich can be improved by compensation is 0.5 to 0.65.Neon tubes are operated withcurrents of 25 mA to 125 mA.In a light tube system a voltage of a maximum 7.5 kV toearth may occur.

In systemswith non-earthed high voltagecircuits, the no-load voltageof the transformer may onlybe 7.5 kV, in systems withcentrally earthed high voltagecircuits 15 kV at the maximum.neon tubesFigure 1.4.6 shows an application of light tubes.stray field transformerNeon tubes are used for advertising purposes, writingand image representations.Certain sequences can berun by special circuits.L1NFigure 1.4.6 Application of neon tubes.Fundamental Principles of Lighting EngineeringLight Sources27Properties of neon tubes:•Luminous efficiency:approx.

35 lm/W (temperature-dependent)•Life:approx. 20 000 h (without influencing the switching frequency)•Light colour:With argon-mercury vapour filling, blue discharge.With neon filling, red discharge.•Inrush and start current:Not above the rated current.1.4.7Compact fluorescent lamps (economy lamps)Compact fluorescent lamps usually have lowpowers and work in the same way as fluorescent lamps. Here too, the current in the gasfilling which contains mercury generatesmainly UV light which the fluorescent materialconverts into visible light. The corners of thecurved tube serve to cool down the gas filling.The temperature of this coolest point in thedischarge system determines the inside gaspressure and thus the discharge properties.The lamp is therefore dependent on the ambient temperature and its position (figure1.4.7.1).

The considerable drop in the lightcurrent „hanging/lying“ should be observed.Economy lamps are available in different versions: with pins for plugging and E27 basethread for screwing.cooling zone10080)(%)60hanging, lying,standing4020free burning lamp,still air06080 100-2002040ambient temperature of the lamp (°C)Figure 1.4.7.1 Light current/temperature behaviour ofcompact fluorescent lampsThe lamps are operated with a built-in electronic ballast.jointfluorescentelectrodeThe advantages of compact fluorescent lamps are:•••••low weightsmall sizehigh luminous efficiencylong lifevarious light colours (partly coloured)Figure 1.4.7.2 shows a compact fluorescent lamp withE27 thread for screwing in.

All functional componentsare installed. The block diagram of the installed EG isshown in figure 1.4.7.3. The individual blocks have thefollowing functions:EG•thread E27••Figure 1.4.7.2 Electronic compactfluorescent lampThe suppresser keeps high-frequency interference voltages away from the mains and protectsthe electronic components against high mainsvoltage peaks.The rectifier converts the mains voltage into a DCvoltage of 300 V.The high-frequency common mode power stagegenerates a high-frequency squarewave voltageof 28 kHz to 45 kHz.28••Fundamental Principles of Lighting EngineeringLight SourcesThe current limiting takes place with a small choke coil.In the heating circuit a cold conductor (PTC) is connected parallel to the lamp which enables preheating in the cold state.

The PTC is high-resistive after flicker-free ignition and therefore no longerconducts.230 V50 Hzsuppresserrectifierhigh frequencycommon modepower stagecurrentlimitingheatingcircuitFigure 1.4.7.3 Principle circuit diagram of a built-in EGCompact fluorescent lamps can be used in place of all common filament lamps. But they are not dimmable. The advantages over filament lamps are:••••••only 20 % of the heat development10 times longer lifeimmediate light after switching onlight colour and colour reproduction properties are the sameno stroboscopic effect in high-frequency operationno shortening of the life by switchingAlthough much more expensive than filament lamps, the operation of a compact fluorescent lamp not onlysaves energy, it is also more economical in the long run.Properties of compact fluorescent lamps:•Luminous efficiency:approx.

2 to 10 times that of a filament lamp•Life:approx. 10000 h•Light colour:similar to daylight1.4.8Halogen high-pressure lampsHalogen high-pressure lamps are also known as halogen metalvapour lamps. The special features of these lamps are a highlight yield and very good colour reproduction properties. Halogen high-pressure lamps are a further development of mercuryhigh-pressure lamps.

Various metal halides of rare earth typesare mixed with the mercury in the combustion chamber whichhave a positive influence on the spectral radiation distribution,colour spectrum and light yield. The lamps are made mainly ofclear glass because an additional fluorescent material is unnecessary due to the naturally good colour reproduction properties.Halogen high-pressure lamps are manufactured in the following versions (see figure 1.4.8.1):1. Compact form:With socket G12, power: 35 W to 150 W2.

Tubular bulb, clear glass:Clear glass, with socket E40, power: 250 W to 3.5 kWFigure 1.4.8.1DesignsFundamental Principles of Lighting EngineeringLight Sources3. Festoon form:Clear quartz glass bulb, with double-ended connection, immediatere-ignition possible with special firing device, power: 70 W to 400 Wsocket29outside bulbpowersupply4.

Tubular bulb with immediatere-ignition:Clear glass, with socket E40 andprotruding connection, immediatere-ignition possible with special firing device, power: 2 kW to 3.5 kWquartz withmetal halidesholderdischarge vesselgetter5. Elliptical bulb:With lightly dispersive coating andsocket E40, power: 250 W to 400 WelectrodesFigure 1.4.8.2 Basic version with screw socket6. Mushroom form:With reflector and socket E40 (bulb with mirroredinside).outside bulb (quartz)Figure 1.4.8.2 shows the basic version with screwsocket and figure 1.4.8.3 the compact form.burnerThe ignition voltage in halogen high-pressure lamps isalways greater than the mains voltage.

Therefore a firing device is usually required in addition to the ballast(choke).getterAll halogen high-pressure lamps may exhibit certain deviations in the colour of the light during operation.molybdenum foilA high voltage firing device is usually necessary to operate halogen high-pressure lamps which does not allow hot re-ignition. If the lamp is to be re-ignited immediately after a power failure, a special firing device is required.socketelectrodespower supplycontact pinsFigure 1.4.8.3 Compact formATTENTION:Lamps which have no or a damaged outside bulb mustnot be used because of the risk of UV radiation!Properties of halogen high-pressure lamps:•Luminous efficiency: 54 to 120 lm/W•Life:After about 6000 hours in operation, the light current drops to 75% of its initial value.•Light colour:The light colour is brilliant white, very similar to daylight with a very good colour reproduction.•Area of application:Film and TV recordings under daylight conditions, reporting (lamps with low power), production (lampswith high power), the stage (drama lighting), professional photography•Light waviness:No visible light waviness at mains frequency.•Start-up current:The start-up current may be 140% of the rated current in halogen high-pressure lamps.30Experiments with the ILLUMINATION BOARDCharacteristic Values of a Filament Lamp2Experiments with the ILLUMINATION BOARD2.1Characteristic Values of a Filament LampTask:Determine the characteristic values of electrical power, illuminance, light current, luminous efficiency, luminous density and quantity of light of the filament lamp used here.

A luxmeter and a power meter are required for conducting the experiment. Use the mains switch for switching on/off the unit.Experiment:•Screw the filament lamp into the socket provided.distribution fieldNL1Q1E1Figure 2.1.1 Experiments setup•Set up the circuit as shown in figure 2.1.1.•Measure the consumed electrical power Pel. of the filament lamp with a power meter.Pel . = W•E=•EVMeasure the illuminance E of the filament lamp with a luxmeter.The illuminance is made up of five different measured values asshown in figure 2.1.2. The respective measuring distance awayfrom the lamp is r = 0.5 m.EV + E H 1 + E H 2 + E H 3 + E H 4= lx5Now use the illuminance to calculate the light current Φ of the lamp.Five sixth of the circumference of a sphere is assumed as an illuminated area.E=ΦAŸΦ = E⋅AwithΦ = E ⋅ A = lmA = 5 6 ⋅ 4 ⋅π ⋅ r 2EH2EH1EH4EH3Figure 2.1.2 Measuring of theilluminance EExperiments with the ILLUMINATION BOARDCharacteristic Values of a Filament Lamp•Now calculate the luminous efficiency η of the filament lamp with the light current.η=•ΦPel .= lmWDetermine the luminous intensity Ι of the filament lamp at a solid angle of Ω = 10.47 sr (5/6 sphere).I=•31Φ= cdΩCalculate the quantity of light Q for a life of t = 1000 h.Q = Φ ⋅ t = Mlmh•Transfer all the values to table 2.1.Pel.

/ WTable 2.1E / lxA/m2Φ / lmη/mxW-1Ι / cdQ / Mlmh32Experiments with the ILLUMINATION BOARDCharacteristic Values of a Halogen Filament Lamp2.2Characteristic Values of a Halogen Filament LampTask:Determine the characteristic values electrical power, illuminance, light current, luminous efficiency, luminous intensity and quantity of light of the halogen filament lamp used here. A luxmeter and a power meterare required to conduct the experiment. Use the mains switch for switching on/off the unit.Experiment:•Screw the halogen filament lamp into the socket provided.•Set up the circuit as shown in figure 2.2.1.distribution fieldNL1Q1E1Figure 2.2.1 Experiments setup•Measure the consumed electrical power Pel. of the lamp with a power meter.Pel . = W•E + EH 1 + EH 2 + EH 3 + EH 4= lxE= V5•EVMeasure the illuminance E of the halogen filament lamp with aluxmeter.

The illuminance is made up of five different measuredvalues according to figure 2.2.2. The respective measuring distance away from the lamp is r = 0.5 m.Then use the illuminance to calculate the light current Φ of thelamp. Five sixth of the circumference of a sphere is assumedhere as an illuminated area.E=ΦAŸΦ = E⋅AwithA = 5 6 ⋅ 4 ⋅π ⋅ r 2EH2EH1EH4Figure 2.2.2 Measuring of theilluminance EΦ = E ⋅ A = lm•Then calculate the luminous efficiency η of the halogen filament lamp with the light current.η=ΦPel .= lmWEH3Experiments with the ILLUMINATION BOARDCharacteristic Values of a Halogen Filament Lamp•Determine the luminous intensity Ι of the lamp at a solid angle of Ω = 10.47 sr (5/6 sphere).I=•33Φ= cdΩCalculate the quantity of light Q for a life of t = 2000 h.Q = Φ ⋅ t = Mlmh•Transfer all the values to the table 2.2.Pel. / WTable 2.2E / lxA/m2Φ / lmη/mxW-1Ι / cdQ / Mlmh34Experiments with the ILLUMINATION BOARDCharacteristic Values of an Incandescent Arc Lamp2.3Characteristic Values of an Incandescent Arc Lamp2.3.1Characteristic valuesTask:Determine the characteristic values electrical power, illuminance, light current, luminous efficiency, luminous intensity and quantity of light of the incandescent arc lamp used here.