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Contents 1 Introduction....................................................................................................................................................4 2 How a metal halide lamp works ......................................................................................................................5 2.1 Quartz discharge tube.............................................................................................................................6 2.
6.3.1 Leaking arc tube .........................................................................................................................27 6.3.2 Increase in re-ignition peak.........................................................................................................27 6.3.3 Broken lead or broken weld ........................................................................................................28 6.3.4 Leaking outer bulb...........................................................
1 Introduction Metal halide lamps offer a number of advantages that favor their use in ever broader areas of application. These include high luminous efficacy, a long service life and good colour rendering. Because the light is generated in a small space, the discharge lamps almost correspond to a spot light source, with advantages in terms of light control and brilliance of the illumination.
In an arc tube, gas discharge works through excitation of the luminous additives (metal halide salts) and the mercury is excited by the current flow. Visible radiation characteristic for the respective elements is emitted.
Ceramic arc tubes can be produced with smaller dimensional tolerances, reducing the variation in lighttechnical and electrical parameters. Multiple lines GREEN Ceramic is less susceptible to attacks from the aggressive metal halide filling and is less permeable for filling particles, resulting in a considerably longer service life compared to quartz tube lamps. YELLOW RED Ceramic arc tubes are now available in various different forms: the original cylindrical version and the improved round version.
9000 h 12000 h Convection Convection Solution of Alumina in MH-melt = Corrosion Condensation of Metall Halides Transport of soluble alumina in MH-melt Evaporation of Metal Halides Evaporation of Metal Halides 1100 Deposition of alumina by saturation of HM-melt due to cooling 1060 1020 Condensation of Metal Halides 980 940 Fig.
3 Ballasts for discharge lamps Since the discharge reacts to increasing lamp current with falling voltage (which would cause the current to rise indefinitely until the fuse blows or another part of the circuit fails), the lamp current must be limited by a ballast during operation. This usually consists of an inductive circuit (choke), although in rare cases up to 400 W capacitive circuits are also possible (although this usually results in a shorter service life).
This lamp behavior results from the relatively flat zero crossing for sinusoidal current. When the current approaches zero, the plasma temperature decreases and the electrodes also cool down. The recombination of electrons with ions reduces conductivity. After the zero crossing, the conductivity is too low to take up the current that the choke wants to drive. As a result, the voltage through the lamp increases again significantly until the lamp “reignites”.
3.1.2 Variation in supply voltage for adapted inductance 3 200 180 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 (PL over UL/UN). 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.
When operating metal halide lamps on a choke, the lamp parameters change depending on the supply voltage. To limit the associated variation in lamp photometrics, a maximum deviation in supply voltage of 5% from the nominal values for the supply voltage is permitted in the short term, or maximum 3% in the long term. For deviations over a longer period of time, suitable ballast tap must be selected.
The parallel capacitor has no influence on lamp behavior. GROUP COMPENSATION, where one joint fixed capacitor is allocated to simultaneously working inductive consumers, similar to individual correction (motors located close together, discharge lamps). Here again the strain on the leads is relieved, but only up to the point of distribution to the individual consumers. Under unfavorable conditions, resonance can be caused in two-phase grids.
ECG Luminaire US Lamp Fig. 13: Simplified circuit diagram showing the electronic operation of high intensity discharge lamps Voltage in V Current in A Time in ms Fig. 14: Current and voltage of a metal halide lamp operated on a rectangular electronic ballast For a conventional ballast, it can be presumed that the service life is defined by the choke temperature tw. A 10 °C increase in the tw temperature means that the service life is halved.
Magnetic ballast Electronic ballast POWERTRONIC® Energy consumption 100 10 to 15% savings over the service life Lamp service life 100 Up to 30% longer depending on lamp type and kind of use Lamp start-up Depends on type: usually approx. 60 to 90 sec.
supply and, above all, a clearly reduced tendency to go out by avoiding re-ignition peaks all lengthen the lamp economic life for ceramic arc tube lamps by up to 30% on average. current of the electronic ballast, producing a higher wattage input into the lamp which therefore heats up more quickly. 3.2.3.4 Size, weight and handling The electronic ballast also shows its strengths at the end of the lamp service life.
so-called harmonic waves whose frequencies are a multiple of the supply frequency (in three-phase supplies these are mainly the fifth, seventh and eleventh harmonic waves). These harmonic waves increase the current of the capacitor for power factor correction, as the reactance of a capacitor decreases with increasing frequency.
3.5 Stroboscopic effect and flicker Operation of a metal halide lamp on a magnetic ballast under supply voltage with 50 Hz frequency results in periodic fluctuation of the luminous flux with double the supply frequency. When the current flow drops near the zero crossing, the plasma also has far less radiation. But even on passing the zero crossing, the luminous flux does not reach zero so that the plasma still has on-going radiation.
There is a delay of just a millisecond between the current maximum and the luminous flux maximum as shown in the following drawing. +200V +8A +7.97V +400VA V MPower Power D C RMS: 150.52 VA MImpedance Impedance D C RMS: Under range 3 1 4 2 TWindow 1 M-- -400VA V -0.033V -8A -200V MM Ch 1: Lamp voltage Ch 3: Light signal (zero-line at the bottom) Ch 2: Lamp current Ch 4: Lamp power Fig.
4 Igniting and starting discharge lamps Some discharge lamps do not require an external ignition unit, as the supply voltage is sufficient to ignite the lamp or because the lamp has an integrated ignition unit. These lamps must not be used in installations with an external ignition unit or they will fail prematurely due to internal arcing. 4.1 External ignition units 4.1.1 Parallel ignition unit Pulser ignition unit choke All other discharge lamps must be ignited by an additional unit.
4.1.3 Superimposed ignitor with symmetrical and asymmetrical ignition pulses. In the asymmetrical units, care must be paid to correct polarity of the lamp connections! Superimposed ignition unit choke Luminaire US Capacitor for PFC Lamp Fig. 21: Simplified circuit diagram for conventional operation of high intensity discharge lamps with a superimposed ignition unit In a superimposed ignition unit, the high voltage is only present at the lamp outputs of the unit.
4.6 Cable capacitance 4.7 Start-up behavior of metal halide lamps The capacitance of the supply cables between lamp and ignition unit depends on various general conditions. These include the size and structure of the cable (diameter, distances and insulation together with number of individual cables, dielectric coefficients of the materials). The capacitance also depends on the grounding and shielding of the cable and where it is fastened, e.g. close to grounded surfaces.
The new round ceramic arc tube (POWERBALL ®) has a uniform wall thickness without thick ceramic plugs as in the cylindrical ceramic type. The mass is therefore only about half that of the cylindrical version. This means less energy and therefore less time is needed to bring the POWERBALL ceramic arc tube up to operating temperature. The times required to achieve the lit-up status are therefore clearly shorter than in the cylindrical version, as shown in Fig. 23.
5 Reducing the wattage of high intensity discharge lamps 5.1 Introduction 5.2 Wattage reduction techniques High intensity discharge lamps generate light by exciting mercury and other metals within an arc tube into a plasma generated by the current flow between two electrodes.
re-ignition voltage and the current supply voltage decreases. If the re-ignition voltage exceeds the supply voltage, the lamp goes out (see also chapter 6.2.2 “Increase in re-ignition peak”). This means that POWERBALL HCI® must not be dimmed by reducing the supply voltage, as the re-ignition peak can cause earlier extinguishing of the lamp or flicker. 5.2.2 Phase control: leading edge, trailing edge Fig.
ing the course of the service life. Lamps of differing geometries and filling also show different resonance frequencies. A reduction in wattage also changes the resonance frequencies due to the change in plasma temperature. 5.3 Recommendations for reducing the wattage in discharge lamps The PTo with squarewave operation and optimised ignition runs the POWERBALL HCI® lamps ideally down to 60% of the lamp output (rated value).
6 Lamp service life, aging and failure behavior 6.1 Lamp service life and aging behavior All lamp-specific electrical and photometric data are ascertained after operating for 100 hours under laboratory conditions using reference ballasts (according to IEC). The service life data are determined under controlled laboratory conditions with a switching rhythm of 11 h on/1 h off. In practice, noticeable deviations can occur due to deviating supply voltage, ambient temperature and other general conditions.
Glow discharge Arc discharge Incandescent lamp mode Fig. 29: Various states of outer bulb discharge 6.3.1 Leaking arc tube High temperatures and pressures in the arc tube, the aggressive chemical substances in the tube and the thermal cycling of a lamp place extreme strains on the arc tube. This can cause the tube to leak, allowing starting gas and filling particles to enter the outer bulb. Depending on the size of the leak, this effect is usually a gradual process.
This is one of the advantages of the rectangular electronic ballast. As the zero crossing for current is very steep, the events of limited current availability are very short and the plasma has little chance to cool down. Lamp voltage Supply voltage Supply voltage Lamp voltage Lamp current Lamp current Re-ignition peak Fig. 31: A lamp goes out because the re-ignition peak is too high Fig.
6.3.6 Breakage or differing wear of the electrodes Breakage of an electrode or differing wear in the electrodes with choke operation can cause a flow of asymmetric current with DC components, which can result in the choke overheating. This effect of asymmetrical conductivity is dealt with in greater detail below. A broken electrode in a ceramic lamp can cause leaks in the arc tube as a result of overheating capillaries, with the effects described above.
The effects are similar to rectifying effect at the start, but the longer persistence can cause overheating of the choke and ignition unit. • Discharge in the outer bulb: As the leads are not geometrically the same, the discharge generated between them can be asymmetrical, with the effects described above. Fig. 32: Asymmetrical conductivity with lamp current and lamp voltage during a normal lamp start. This is only a transient effect which causes no harm.
Rectifying effect causes a high DC current component. As a result, the choke goes into saturated state with a marked decrease in choke impedance. In extreme cases, the lamp current is only limited by the choke’s ohmic resistance. Permanently excessive current causes a dramatic increase in the temperature of the choke windings until the insulation is destroyed and short circuits occur between the choke windings.
7 Luminaire design and planning of lighting systems 7.1 Measuring temperatures, ambient temperature 7.1.
• When measuring the outer bulb temperature, corresponding evaluation must consider the radiation (cooling-down curve) 7.1.3 Measuring points for thermocouples in different lamp types The radiation of the arc tube heats up the thermocouple on the outer bulb above the temperature of the quartz glass on which it is positioned.
7.1.3.1 HCI®-TC G8.5 7.1.3.4 HCI®-E and E/P / HQI® E27 and E40 Pinch temperature (in base up burning position) • Base edge temperature (in base up burning position) • Outer bulb temperature (in horizontal burning position) Outer bulb temperature (in horizontal burning position) • • 7.1.3.2 HCI®-T / HQI®-T G12 (similar for the HCI®-TM and HQI®-TM G22) Pinch temperature (in base up burning position) 7.1.3.
7.1.3.7 HCI®-TS, RX7s, RX7s-24 and HQI®-TS Fc2 Outer bulb temperature (in horizontal burning position) 7.1.3.10 HQI®-T, ≥ 1000 W Base edge temperature (in base up burning position) • • •• Outer bulb temperature (in base up burning position) Pinch temperature (in horizontal burning position) • Outer bulb temperature (in horizontal burning position) • • Base edge temperature (in horizontal burning position) 7.1.3.8 HCI®-PAR E27 Base edge temperature (in base up burning position) 7.1.3.
7.2 Influence of ambient temperature on ballasts and luminaires As the ambient temperature increases, the temperature of the luminaire components also increases at the same rate. The lamp reacts to a higher ambient temperature with an increase in lamp voltage and lamp wattage. This can accelerate corrosion and aging processes. An increased re-ignition peak can result in failure by the lamp going off at an earlier point in the service life.
At the end of the lamp service life, higher temperatures than normal can occur in the pinch area caused by outer bulb discharges. The socket must be rated accordingly (see also chapter 6.2.1 Leaking arc tube). When replacing such lamps, the socket must always be checked for signs of damage and replaced if necessary, because a damaged socket would also damage the new lamp. • Rated current and rated voltage The socket must be chosen according to the lamp parameters.
Example for a maintenance plan Maintenance plan Only regular maintenance can ensure compliance with the stipulated illuminance levels in the EN 12464 standard for the lighting system. The following maintenance intervals must therefore be followed. Room Type of surrounding: Normal Maintenance interval: every 2 Years Luminaire XXX Influence of reflections from the room surfaces: medium (Room index 1.1 < k < 3.
Table 2: Comparison of change intervals for different lamp types Lamp HCI-T 70 W/830 PB Case 1 Case 2 Case 3 Maintenance intervall 3 Years 3 Years 1 Year 2 Months Operating hours /year 3000 3000 3000 yes yes yes LLMF according CIE POWERBALL HCI® according CIE RMF 0,95 0,95 0,95 LWF 0,8 0,8 0,8 LSF 1 1 1 LLMF 0,68 0,8 0,8 MF 0,52 0,61 0,61 Immediate exchange of defect lamp Diagrams showing luminous flux behaviour and survival rate can be found in the Technical Data of
Table 3: IEC standards for discharge lamps and accessories Lamp Safety 62035 Performance Discharge lamps (excluding fluorescent lamps) – Safety specifications 60188 High-pressure mercury vapour lamps – Performance specifications 60192 Low-pressure sodium vapour lamps – Performance specifications 60662 High-pressure sodium vapour lamps 61167 Metal halide lamps 61549 Miscellaneous lamps Bases, sockets and gauges 60061-1 Lamp caps and holders together with gauges for the control of interchangeabil
Accessories Performance Safety 61347-2-6 Lamp control gear – Part 2-6: Particular requirements for d.c. supplied electronic ballasts for aircraft lighting 61347-2-9 Lamp control gear – Part 2-9: Particular requirements for ballasts for discharge lamps (excluding fluorescent lamps) 61347-2-12 Lamp control gear – Part 2-12: Particular requirements for d.c. and a.c.
If an ENEC mark is issued for a product by a certification body, then the European certifying bodies participating in the ENEC agreement treat this product as if they had tested and certified it themselves. Further testing and certification by one of these bodies is no longer necessary. The ENEC mark can be obtained for luminaires for which a European standard exists.
on the outer bulb and the socket or the pinch area first need to be measured as stated in the catalogues, see also section 7.1. However it should be noted that even if the temperatures measured on the outside of the lamp lie within the defined tolerance values, this does not necessarily mean that there is no overheating inside the lamp. Those surfaces closely surrounding the lamp, such as the reflector neck, diffuser tube and glare shield caps, reflect back on the lamp.
If back reflecting construction elements are used in the luminaire design, the guarantee for the lamps can be restricted or even completely suspended. It is therefore recommended contacting OSRAM if there is any doubt during the design stage. In the case of lamps with back reflecting construction elements, tests should always be carried out to ascertain whether the extent of the lamp damage can at least be assessed as minimal.
8 Light and colour Light is the part of the electromagnetic spectrum which can be seen with the eye. By definition, the perceptible wavelength range is 380-780 nm, although radiation can also be perceived as colour in the near infrared range. Similar to visible light, ultraviolet and infrared variation belong to the electromagnetic spectrum. V(λ) V’(λ) (Night vision) L < 0,1 cd/m2 (Day vision) L > 30 cd/m2 Fig.
8.1 Night vision The luminous flux, measured in lumens, is the irradiated output of a light source evaluated by the eye. It is defined by multiplying the physical radiation output with the eye sensitivity curve V(λ). Standard luminous flux measurements only consider the reaction of the eye at high illuminance levels (photopic vision) as is typical for daylight and indoor illumination. Luminous flux measurements measure photopic light as perceived by the central region of the eye.
Weighting factor for eye sensitivity curve Fig. 48: Relative luminous flux in lumen per 1000 lm and per 5 nm Illumination levels in street lighting are higher than 0.1 cd/m², resulting in a sensitivity between photopic and scotopic vision. Weighting factor for eye sensitivity curve In Fig. 49, the radiation output has been multiplied by the V'(λ) curve for illumination levels below 0.1 cd/m².
8.2 Colour rendering One way of showing the colour impression is the standard chart as per DIN 5033 – basic stimulus. Colour is a sensory impression conveyed by the eye. The evaluation of a colour stimulus by the eye causes a uniform effect (colour stimulus specification). This can be described by colourimetric numbers (e.g. x, y and z in the CIE 1931 or CIE 1976 colour space or L, a and b in the CIE 1976 (L*a*b*) space or W, U and V in the CIE 1964 colour space (W*, U*, V*)).
Larger deviations are associated with a clear tint. The distance to Planck is also known as the chromaticity gap Δc. Colour rendering is specified by irradiating defined test colours in succession with a reference source (an ideal Planck radiator with the temperature and therefore colour temperature of the test light source) and with the test light source. The specific resultant colour shift ΔEi is defined for every test colour i in the uniform colour space CIE 1964 (W*, U*, V*).
has become possible due to additional adaptation of the HCI® Shoplight, which achieves the best colour rendering properties of all metal halide lamps. Figure 49 shows the values of the colour rendering indices 1 to 14 for four different lamp types with the correlated colour temperature of 3000 K. The advantages can best be seen for colour rendering index R9 for saturated red, but the superiority of POWERBALL ® technology is also apparent for the other colour rendering indices. 8.
circadian function visual sensitivity spectral sensitivity And so we distinguish between the visual path, responsible for all visual tasks such as recognizing pictures, perceiving brightness, contrast, shapes, etc., and the non-visual path, or also “biological path”, which controls in particular the circadian rhythms and also influences in the daytime our alertness and mental performance and also biological functions such as hormone production, the blood circulation and the metabolism.
OSRAM metal halide lamps comply with the limit values of 2 mW/klm or even go below the limit considerably. Exceptions are the HQI® lamps without outer bulb with the power of 1000 W and 2000 W. Here special safety precautions have to be met by the luminaire. Standardization of UV variables per “klm” or “lm” offers the advantage of being able to make direct comparison of the relative radiation shares of various lamp types and wattage classes with regard to the same application illuminances.
9 Disposal of discharge lamps High-pressure discharge lamps contain small quantities of mercury as an environment-relevant substance. Metal halide lamps can also contain thallium iodide as an additive. This is why discharge lamps must be disposed of separately from domestic waste and industrial waste similar to domestic waste. The last owner is obliged to dispose of the discharge lamp using the correct procedure. Breakage of high-pressure discharge lamps emits traces of toxic mercury and thallium halides.
10 List of abbreviations 54 ACGIH American Conference of Governmental Industrial Hygienists AGLV Arbeitsgemeinschaft Lampen-Verwertung (Lamp recycling consortium) ANSI American National Standards Institute CE Communauté Européenne (European Community) CIE Commission Internationale de l‘Eclairage (International Lighting Commission) DALI Digital Addressable Lighting Interface (communications standard for lighting systems) CISPR Comité international spécial des perturbations radioélectriques (Sp
11 Literature [1] Kelly, D. H. (1961) Visual Response to Time-Dependent Stimuli. I. Amplitude Sensitivity Measurements. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA Vol. 51, Nr 4 On Pages: 422-429 Henger, U. (1986) Untersuchungen zur Entwicklung eines Messgerätes zur Bestimmung des Flickerfaktors. Licht 86 7. Lichttechnische Gemeinschaftstagung. [2] Afshar, F. 2006. Light Flicker-Factor as a Diagnostic Quantity for the Evaluation of Discharge Instabilities in HID Lamps. LEUKOS Vol.
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