What device of xenon lamps?
In recent years gas discharge tubes of the ultrahigh davyoleniye in which not vapors of metals, but tyayozhely gases, in particular xenon are used receive more and more wide rasyoprostraneniye. Use of xenon makes essential changes to characteristics of these lamps. The razgoraniye period in xenon lamps of the praktiyocheska is absent as gas density in the lamp does not depend on flask temperature. Therefore at once after ignition in the discharge lamp it begins to work in the noyominalny mode. It is convenient from the point of view of the ekspluayotation. The discharge in xenon has the good spectral characteristics of radiation close to the range of solnechyony light. In this regard xenon lamps have the hoyoroshy color rendition.
Radiation of xenon lamps богато ultraviolet and infrared rays.
At some values of current of the lamp get the positive volt-ampere characteristic that allows to feed lamps of the certain power without ballast (ballastless lamps). Use of such lamps is economic as at their inclusion in network there are no unproductive losses in ballast. Xenon lamps have rather low working nayopryazheniye when burning, but for achievement of big brightness of discharge and increase in their light return priyokhoditsya to increase lamp current. Therefore characteristic of these lamps is rather big current.
On the profitability xenon lamps hold average position between glow lamps and mercury-quartz lamps of high pressure. Light return of xenon lamps depending on power on average makes from 20 to 50 lm/W. The service life guaranteed by the plants fluctuates from 200 to 1000 h.
Can seem that at the specified economic parameters of lamps their application is not reasonable. However the carried-out calculations and the available practice of use of xenon lamps allow osnovayony to claim that use of xenon lamps in some cases is very reasonable and economic. The most favorable scopes of xenon lamps can be considered naruzhyony lighting of big squares in the cities, illumination of sports constructions, illumination of pits when developing in the open way, lighting of open building sites and mounting pads of the proizvodyostvenny enterprises and also internal lighting of production workshops of the big sizes and more than 20-25 m high now. Considerable application is found by xenon lamps in film projectors, when shooting color movies, in television and theatrical publicizing and some other special installations.
Design of xenon lamps
Distinguish two osnovyony types of xenon lamps: lamps in spherical flasks with the short arch, with distance between electrodes in several millimeters with ambient or vozdushyony cooling and lamps in tubular flasks with the dlinyony arch with ambient or water cooling.
The lamp with the spherical flask (fig. 1) represents soyoby the thick-walled cylinder from quartz with two electrodes which are sealed in it made of thoriated tungsten. Conducting contacts служат cylindrical conclusions which design provides both the possibility of fastening of lamps, and accession of the feeding wires. The cylinder of the lamp nayopolnyatsya by xenon up to the pressure of 8-9 ат which during the work of the lamp increases till 20-25 ат.
Lamps can work at direct and alternating current. Difference of these lamps - in the design of electrodes. At the direct current the lamp has very massive anode (fig. 1a) located above. At alternating current both electrodes have the identical design (fig. 1b).
The tubular xenon lamp with the natural okhlazhyodeniye (fig. 2a). represents the thick-walled tube from the quartz glass on which ends electrodes from thoriated tungsten are welded in. Inputs of the lamp are produced from the molybdenic foil. Vneyony conclusions are made of steel, and transitional plugs - of titanium. The flask of the lamp is filled with xenon, its pressure is from 15 to 350 mm Hg.
The size of pressure of xenon is defined by tension the zazhigayoniya of the starting arrangement and also depends on the chosen internal radius of the tube and voltage drop per unit length of discharge. In lamps with water cooling the digit tube from quartz is located in the glass cylinder (fig. 2b). In the gap between the digit tube and tsiyolindry water which is given the vintoyoobrazny movement thanks to some shift of the vkhodyony branch pipe in relation to the plane passing through the lamp axis circulates. The ends of the glass cylinder are located in combined brass couplings and are condensed with rubber laying.
For cooling of lamps the distilled water circulating in the closed system is used. Normal work of the lamp is possible if the glass cylinder is completely filled with water. Mayoksimalny temperature of the cooling water should not exceed temperatures at which the sploshyony steam shirt is formed (no more than 50 °C at the exit from the lamp). For these reasons the consumption of okhlazhyodayushchy water is defined. Primeyoneny the water okhlazhyodeniye allows to uveliyochit almost by 10 times the unit load on quartz in comparison with the natural okhlazhyodeniye that gives the vozyomozhnost to reduce the sizes of the lamp and at the same time to raise their light otdayocha for 30-40%.
Ignition of ksenonoyovy lamps
Tension of ignition of xenon lamps considerably preyovyshat tension of the power line, the poetoyoma the setting fire ustyoroystvo is based on the principle of the spark generator. Schemes of ignition of the lamp by means of the spark generator are provided on fig. 3. For ignition of lamps not only the size of the setting fire impulse and number of the impulses given on the lamp, but also phase shift between the supply voltage of the lamp and starting ustroyyostvo have important znacheyony. At the power supply of the lamp and the starting arrangement from the same phase of network tension of ignition of the lamp is higher, than at the power supply from different phases. Therefore to the starting arrangement and to the lamp different phases of network move. Contacts of the contactor of R1 in case of automatic control of ignition of lamps on peryovichny transformer winding of T1 the network nayopryazheniye moves.
The C1 condenser which is switched on in secondary winding of the transformer is charged, and when on it is mute tension reaches the size of breakdown voltage of the air discharger P, it razryayoditsya almost instantly on the primary winding of the pulse transformayotor T2. In secondary winding of the T2 transformer it is induced high-voltage, high-frequency импульс which will be attached to lamp electrodes. Under the influence of this impulse the digit promezhuyotok of the lamp will break through that will cause its initial ionization.
If the size and number of the given impulyyos are sufficient, then in the lamp necessary conditions for development of the electric arc are created, and the lamp is lit. After the lamp was lit, it is necessary that the spark generator continued to raboyotat during some period. If to switch-off the spark generator before put vreyomen, then the lamp can go out. Time, during koyotory the spark generator has to continue to raboyotat, depends on tension and the total resistance of network. The necessary endurance of time is provided with introduction to the scheme of the timing circuit (on the scheme it is not shown).
When process of ignition of the lamp ends, the podzhiyogayushchy device is switched-off from the lamp. The K1 button is for this purpose disconnected, and secondary winding of the impulsyony transformer becomes isolated short the K2 button. In case of automatic control of the timing circuit the contactor (it is not shown on the scheme), who the contacts switches-off the T1 transformer and zayomykat short secondary winding of the transformayotor of T2 includes. The C2 condenser serves for protection of network against the poyopadaniye in it high tension.
Lamps with power up to 6 kW can join on two consistently on voltage of 220 V and to be lit by one incendiary device.
It is necessary to pay attention to placement of the puskoyovy device. It has to be placed not further 30 m from the lamp, otherwise it will reduce the size of the high-voltage impulse. As the size of this impulse is 20-50 kV, the izoyolyation of the wire connecting the lamp to the starting arrangement has to be chosen at the rate on the rated voltage of 15-20 kV.
At disconnection of the lamp from network its repeated inclusion is possible only after dostayotochny cooling on what 5-10 min. are required to Povtoryony inclusion of not cooled down lamp can put it out of action therefore it should be avoided.Top