RU2291515C1 - Method for protecting multiple-lamp light emitter against thermal destruction - Google Patents

Abstract

FIELD: specific fields of electrical engineering including lighting engineering; miscellaneous lighting systems and devices.

SUBSTANCE: novelty in proposed method for protecting louvered multiple-lamp light emitter with lamps spaced apart through distance d against thermal destruction by preventing lamp overheating is that overheating of lamps is prevented by passing additional current I in emitter plane simultaneously with main current I_l through lamps. To this end current-conducting compensating devices spaced apart through distance d are installed in parallel with lamps on emitter edges at distance d from extreme lamps symmetrically to emitter longitudinal axis; additional current is found from equation I = NI_l, where N is rounded to integer L/d ratio; L is maximal distance between two separate emitter lamps preventing ponderomotive adherence of discharge at current I_l to lamp walls; d is lamp installation pitch. Additional current is chosen to be unidirectional with main current.

EFFECT: enhanced service life, total energy of light flux, and glow surface area of emitter within wide spectral range.

1 cl, 6 dwg

Description

The invention relates to special fields of electrical engineering, in particular to lighting engineering, and can find application in the development and construction of lighting systems and equipment for a wide range of applications used in biological and chemical treatment of water and air, in photolithography, in lighting design of entertainment events and advertising objects, when solving special applied problems.

The most efficiently listed tasks can be solved by using lighting systems based on powerful multi-channel widescreen lattice light sources. By lattice design, we mean the design of the emitter, in which the tube lamps are located in the same plane parallel to each other with a constant installation step d and have unidirectional currents. In this case, it is preferable to use sealed tube discharge lamps as emitters, which have higher operational parameters compared to leaky tube emitters and surface discharge emitters, as well as serviceability.

One of the main requirements for such lighting installations is to ensure a high specific density of light energy per unit surface simultaneously with a large area of the luminous surface.

When creating multichannel lattice tube structures with unidirectional current, developers are faced with a serious problem of deflecting the discharge channel to the walls in the electrode regions of tube lamps installed in the same plane due to the action of ponderomotive forces, which are significant in conditions of high power supplied to the emitter, sufficient for adhesion the discharge channel to the walls of the bulb inside adjacent lamps, close to the edges of the multi-tube emitter. The result of these forces is the fusion of quartz flasks of gas discharge lamps in the electrode regions, accompanied by the release of impurities from quartz that precipitate on the inner surfaces of the lamps.

All this leads, firstly, to a sharp limitation of the duration of the luminescence cycle due to the possibility of through penetration of quartz and depressurization of lamps at high levels of input power, secondly, to a decrease in the luminous flux of impurities deposited on the lamp walls, and thirdly, to a time limit lamp service due to accumulated over time violations of the structure of their walls in the electrode regions during their cyclic local overheating.

A known method of protection from thermal destruction of a multi-tube trellised light emitter [Powerful pulsed irradiation installation, Yu.G. Basov, BC Prokudin and other Lighting Engineering, 1990, No. 8, p.10-12] by preventing overheating of the lamps by providing convective air heat exchange with environment due to the formation of air gaps between the individual lamps and gaps between the lamps and the reflector of the emitter.

This method cannot provide protection against thermal destruction of a multi-tube radiator with a trellised structure with unidirectional lamp currents at high input electric power.

As a prototype of the invention, we have chosen a method of protection against thermal destruction of a high-power laser array light emitter [RF Patent No. 2108647, IPC H 01 S 3/03, prior. 06/25/96] by preventing overheating of the lamps by forced pumping of refrigerant along the outer surface of their walls and removal of excess heat from the heat release zone.

When implementing this method of protection, the electric power supplied to the lamps can be significantly increased in comparison with the analogue, however, its further increase is limited by local overheating of the walls due to ponderomotive adhesion of the discharge. In addition, part of the light energy is absorbed by the refrigerant, which reduces the light parameters of the emitter.

Our proposed method of protecting a multi-tube light emitter from thermal destruction during its implementation allows us to provide a high lifetime of the emitter, a high total energy of the light flux and a large surface area of the glow in a wide spectral range.

This result was achieved by the fact that in the known method of protecting a multi-tube, with the step d installation of lamps, trellised type light emitter from thermal destruction by preventing overheating of the lamps, overheating is prevented by the formation of additional currents I in the plane of the radiator along with the main currents I _l , distributing them with a step d from the emitter, symmetrically relative to its longitudinal axis (in this case, by the longitudinal axis of the emitter we mean the line in the plane of the emitter, dividing it in half and unidirectional associated with lamp currents), and found from the relation I = NI _l , where

N is the rounded to the whole L / d ratio, where

L is the minimum distance between two separate lamps of the emitter, at which there is no ponderomotive adhesion to the walls of the discharge lamp with a current of I _L ;

d is the lamp installation step,

while the additional current is selected unidirectional with the main current.

The value of the step d between the lamps of a multi-tube light emitter is set for reasons of ensuring the necessary uniformity of illumination, known from lighting engineering.

We have shown that it is possible to eliminate the phenomenon of sticking of a discharge in lamps of a multichannel emitter by compensating for the internal ponderomotive forces by external ponderomotive forces using the regularity that we identified, which determines the dependence of the compensating current and its distribution in space on the magnitude of the adhesion boundary.

Figure 1 shows a diagram illustrating the dependence of the zone of adhesion of the discharge to the walls of the lamp on the magnitude of the current flowing through the lamp, and the distance between the lamps; the abscissa axis represents the distance L in relative units between two separate emitter lamps, and the ordinate axis represents the current I in relative units through the emitter lamp:

L _max , L _min - the maximum and minimum distances between the lamps, respectively;

I _max , I _min - the maximum and minimum values of currents in lamps, respectively;

A, B, C, D, F - points that limit the zone of adhesion of the discharge in the lamps.

Figure 2 shows the options for the distribution of currents in a multi-tube panel, operating in accordance with the proposed method. Figures 2a and 2b show variants of a circuit with a branched and unbranched additional current, respectively, where the total current I _{Σ of} lamps, current I of one lamp, step d of installing lamps and additional current conductors, the distance L _from the return current path of the compensating device:

L1 ÷ L4, L11 ÷ L14 - lamp numbers in a 14-tube emitter;

T ₁ ÷ T ₈ - numbers of current conductors in compensating devices; arrows indicate the direction of current flow; dotted lines indicate the central group of emitter lamps.

Figure 3 shows a photograph of a 14-tube emitter operating in accordance with the proposed method, where 1 is an IFP-16/580 type lamp, 2 are reflectors, 3 are compensating devices; l is the width of the emitter.

Figure 4 shows photographs of the discharge channels in the lamps of a 14-channel emitter with unidirectional currents. Figure 4a shows a photograph of the discharge channels for a lamp panel without compensation for internal ponderomotive forces, and Figure 4b shows a photograph of a lamp panel in which the proposed method is used, where 4 are the lamp walls, 5 are the lamp cathodes, and 6 is the discharge inside the lamp.

The proposed method of protection against thermal destruction of a multi-channel light emitter is as follows. To implement the method, I _l currents are formed in two separate tube lamps of the emitter, the value of which corresponds to the maximum values of currents I _max that will be achieved during operation of the device, and find the distance L between these lamps, at which there is no ponderomotive adhesion of the discharge to the lamp walls at this current . The diagram of Fig. 1 shows how the adhesion limit depends on the current value in the lamps. Here, two characteristic regions can be distinguished, one of which, the ABDF region, characterizes the set of parameters L and I, in which the mode with adhesion is realized, and the other region BCD - the regime without adhesion. Here I _L = I _max , and I _min corresponds to the discharge holding current in the lamp, that is, the minimum lamp current at which the discharge does not go out yet. During the operation of the emitter, the current in its lamps can be forced to change in the range from I _min to I _max depending on the tasks to be solved, but the selection made L = L _max will ensure in the future the discharge does not stick to the walls of the lamps in the entire range of currents. Next, find the L / d ratio and round off the value of this ratio to an integer N. Simultaneously with the formation of the main lamp currents, additional currents I are formed, which have the same direction with the main lamp currents and a value equal to I = NI _l . In this case, additional currents I acting by means of ponderomotive forces on the discharges in the lamps are distributed with a step d from the emitter symmetrically relative to its longitudinal axis.

Note that in devices of this type necessarily have reverse current conductors, the location of which is chosen for reasons known from electrical engineering.

Let us compare the work of the proposed method with the prototype, where the effect on the thermal energy of the lamps is reduced to providing heat removal from their external surface by pumping refrigerant. The implementation of the prototype method in a radiator with a large input electric (and, accordingly, thermal) power with a unidirectional current in the lamps will not only not protect the lamps from thermal damage, but, on the contrary, will aggravate the situation. Indeed, by increasing the supplied power by increasing the current in the lamps, at some point, a current value is reached at which for a given lamp installation step, ponderomotive adhesion of the discharge to the lamp walls in the electrode regions and, accordingly, their local overheating. In this case, the use of forced heat removal from the surface of the bulb of the lamps by pumping refrigerant will increase the temperature gradient on the walls of the bulb and, to the greatest extent, in the zone of adhesion of the discharge. Accordingly, even before the fusion of quartz in the adhesion zone, it cracks under the influence of a temperature gradient, as a result, the refrigerant enters the discharge zone, which will lead to explosive destruction of the lamp bulb.

Different processes occur when using the proposed method. In this case, the increase in the power supplied to the emitter by increasing the current in the lamps is accompanied by a corresponding increase in the additional currents in the compensating devices. Moreover, the choice of the magnitude of the additional currents and their spatial distribution, based on the patterns found by us when creating the invention, provides full compensation for the internal ponderomotive forces of the emitter. This excludes ponderomotive adhesion of the discharge to the walls of the lamps, there is no local localization of thermal power in their near-electrode regions and its uniform distribution along the walls of the lamps is ensured, which eliminates local overheating, leading to thermal destruction of the lamps.

An example of a specific implementation.

At the request of Minatom, a 14-lamp emitter operating in accordance with the proposed method was manufactured at our enterprise, a photograph of which is shown in Figure 3. The emitter with a width l = 780 mm is made on the basis of INP-16/580 xenon discharge lamps (position 1) installed in the same plane parallel to each other with a pitch of d = 40 mm in front of the reflectors 2, which are a polished aluminum profile. Based on the maximum value of the lamp current I _l = 250 A, determined by the capabilities of the power source (KTEU-4000 thyristor unit), the discharge sticking limit L = 150 mm was established by filming the discharge in the electrode area of the lamp at different distances between two separate emitter lamps. The number N in this case was N = round. (150/40) = 4. In the first version, compensating conductive devices were installed on the edges of the emitter at a distance of 40 mm from the extreme lamps in the same plane as the emitter lamps, each of which was 4 copper stranded bare wires with a cross section of 25 mm ² each, installed in parallel with the lamps with a pitch of 40 mm each from friend. For each of these wires, simultaneously with the formation of the currents of 14 lamps, the magnitude of which was 250 A per lamp, a current of 250 A was passed, which was provided by the connection diagram shown in Fig. 2a. Thus, a current I = N * I _l = 4 * 250 = 1000A was distributed over each edge of the emitter. In the second embodiment of the proposed method, which corresponds to the photograph shown in Fig. 3, compensating conductive devices 3 were installed on the edges of the emitter at a distance of 40 mm from the extreme lamps in the same plane as the emitter lamps, each of which was a single copper stranded bare wire with a cross section 80 mm ² . For each of the compensating conductive devices, simultaneously with the formation of currents of 14 lamps, the magnitude of which was 250 A per lamp, a current of I = N * I _l = 4 * 250 = 1000A was passed, which was provided by the connection diagram shown in Fig. .2b. Thus, in this case, a current I = N * I _l = 4 * 250 = 1000A was distributed over each edge of the emitter. In both versions used, each of the wires of the conductive compensating devices was placed in a cylindrical quartz shirt of the same diameter with the diameter of the emitter tubes, which, on the one hand, made it possible to use fasteners for these wires identical to the fasteners for the lamps, and, on the other hand, prevented high-voltage breakdown in air to the wires of compensating devices for pulse ignition of lamps. Approaches to solving such technical problems are known. The return conductors of compensating devices, to exclude their influence on the distribution of currents in the lamps, were located at a distance L _from = 1 m from the lamps closest to them.

Figure 4 shows photographs of discharges in the extreme lamps of the 14-lamp panel, illustrating the action of external ponderomotive forces. As can be seen in Fig. 4a, for a lamp panel without compensation of internal ponderomotive forces, the discharge channels are pressed against the walls of the lamps in the cathode region, which leads to local fusion of quartz shirts in the emitter tubes. At the same time, the photograph of Fig. 4b illustrates how, under the action of external ponderomotive forces, a uniform distribution of the discharge channels inside the lamps is ensured by squeezing the discharge from the lamp walls with the magnetic field of the compensating device. Naturally, in this case, the point supply of thermal energy to the lamp bulb is eliminated, which prevents its destruction.

Each of the implemented options, providing reliable protection of the emitter lamps from thermal destruction, has one or another advantage. So the first option is preferable to use in the case when the installation does not have requirements that limit its size. In this case, due to the distribution of the compensating current over four branches from each edge of the lamp panel, the specific thermal load on the compensating device, which is determined by the total effect of the Joule heat and heating by light radiation, is reduced. Accordingly, the second option is best used in conditions of overall restrictions, since it provides an overall reduction in size. So in the case of the 14-lamp panel we used, this reduction was 40% compared with the first option.

Claims (1)

A method of protecting a multi-tube, with d installation of lamps, trellised type light emitter from thermal destruction by preventing overheating of the lamps, characterized in that overheating is prevented by the formation of additional currents I in the lamp plane along with the main currents I _l by installing in the same plane as the lamps the radiator and parallel to them compensating conductive devices located with a step d along the edges of the radiator at a distance d from the extreme lamps symmetrically with respect to its longitudinal axis, with than the additional currents I are found from the relation I = NI _l where N is the rounded to the whole L / d ratio, where L is the minimum distance between two separate lamps of the emitter, at which there is no ponderomotive adhesion to the walls of the discharge lamp with a current of I _l ; d is the lamp installation step, while the additional current is selected unidirectional with the main current.

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