EP0196249B1 - Lighting system, especially for a water-tight airport coffer - Google Patents

Description

The invention lies in the fields of public lighting or intended for the public.

FR-A 2,430,707 is already known for lighting installations comprising an AC power supply circuit, of the regulated current loop type. Such a regulated current loop, which generally operates at alternating medium voltage, travels in series through the primary windings of medium voltage / low voltage transformers. Through their secondary, these transformers in turn each supply a plurality of lighting devices, electrically connected in series, and belonging to respective indicator boxes.

Such indicator boxes are often used, especially in airports. Their front face is provided with an indication intended for the users, for example an arrow or a letter. Until now, these indicator boxes have mostly been fitted with metal halide filament lamps, similar to those used for beacon lights. A detailed example of the structure of such a known box will be given below.

These known installations have various drawbacks, the main ones of which are on the one hand the fact that the luminous efficiency of filament lamps with metal iodides is not very high, and on the other hand the fact that the life of these same lamps is relatively small.

The main object of the present invention is to improve this kind of installation.

For this, the invention provides a lighting device suitable for being part of a lighting installation of the type defined above.

According to a first aspect of the invention, each lighting device comprises a current transformer, the secondary of which supplies at least one fluorescent lamp, with its ignition / regulation members; the primaries of the current transformers of the various lighting devices are intended to be mounted in series in the secondary circuit of the medium-voltage / low-voltage transformer, the primary circuit of which is reminded that it is supplied by the regulated current loop; finally, the secondary of each current transformer is provided in parallel with clipping devices capable of consuming, when the associated lamp fails, a substantial fraction of the nominal energy required by the latter. This preserves the flow of nominal current to the primary windings of the other current transformers, thus ensuring the proper functioning of the rest of the installation.

In one embodiment, the clipping members consist of two high voltage clipping diodes, mounted in head to tail series.

According to another aspect of the invention, there is provided, in parallel on the secondary of the current transformer of the device, a tuning member capable of providing an overvoltage characteristic by resonance.

Advantageously, this characteristic of overvoltage by resonance is adjusted so that the secondary alternating voltage supplied decreases very quickly as soon as the secondary load increases, which accelerates, the ignition of the fluorescent lamp, and that the current passing through the organs of clipping is greatly reduced as soon as the secondary voltage reaches the clipping value.

Such a tuning device may include a capacitor.

According to yet another aspect of the invention, each lighting device comprises two lamps connected alternately by an inverter to the secondary of the current transformer, and switching means, which react to the number of lights of a first lamp during a time greater than its ignition time by actuating the inverter to put the second lamp into service.

Mechanically, such a device may include a base plate provided with oblong fixing openings, and which supports a block of overmolded synthetic material, having an intermediate level where the lamp or lamps are mounted, and a higher level from which the terminals of the primary of the current transformer emerge; the electronic circuits and this transformer are embedded in said block.

The switching means will then preferably comprise a photodetector housed in a column removably mounted on this block, and capable of bringing the photodetector substantially into contact with the illuminating part of the first lamp.

• - la figure 1 illustre une installation d'éclairage de la technique antérieure;
• - la figure 2 illustre une installation d'éclairage selon l'invention;
• - les figures 3A et 3B sont deux vues correspondantes, respectivement de dessus et de gauche, d'un dispositif élémentaire selon l'invention; et
• - la figure 4 est le schéma électrique détaillé d'un mode de réalisation du dispositif de l'invention.

Other characteristics and advantages of the invention will appear on examining the detailed description below, as well as the appended drawings, in which:

• - Figure 1 illustrates a lighting installation of the prior art;
• - Figure 2 illustrates a lighting installation according to the invention;
• - Figures 3A and 3B are two corresponding views, respectively from above and from the left, of an elementary device according to the invention; and
• - Figure 4 is the detailed electrical diagram of an embodiment of the device of the invention.

FIG. 1 shows a medium voltage circuit MT, arranged in a regulated current loop BDCR, and comprising n times a medium voltage / low voltage transformer. This therefore has a medium voltage PMT primary and a low voltage secondary SBT each time.

By now considering only a single medium-voltage / low-voltage transformer, the low-voltage circuit thereof supplies several indicator boxes CI1 to C14 in series.

According to the prior art, each indicator box comprises for example two metal halide filament lamps, such as the lamps LF11 and LF12 for the box 01. Most often, these two lamps are arranged one at the top and the another in the lower part of the box.

Those skilled in the art will understand that the failure of a single lamp interrupts the secondary circuit BT, which could thereby prevent all of the indicator boxes from operating.

To remedy this, it is customary to provide a controlled short circuit in parallel on each lamp. The principle is as follows: when a lamp does not work, this is detected by any known means, and a triac in parallel on the lamp is then triggered, which short-circuits the faulty lamp and then allows other lamps to function.

Typically, each box uses two 45 watt lamps electrically connected in series. All the boxes are themselves connected in series to the low voltage terminals of an isolation transformer, the primary of which is supplied by a constant current loop between 5.5 and 6.6 Amps.

The electrical power consumed is therefore at least 90 watts per box. It is actually a little higher, if we consider the reactive current losses as well as in transformers.

Reference is now made to FIG. 2, which defines the block diagram of an installation according to the invention, compared with FIG. 1.

The structure is the same up to the low voltage circuit. Now, this one, which always passes through the indicator boxes CI1 to CI4, meets in each box a device D1 to D4, respectively. Each of these devices is mounted substantially in the center of the box. As will be seen below, it has two lamps capable of operating alternately, that is to say that one can make up for the deficiencies of the other.

It will be noted that, independently of the problems which he had to solve, the Applicant was able to observe that fluorescent lamps used according to the invention, and even with a clearly lower power than that of the prior art, nevertheless made it possible to obtain completely satisfactory lighting in a box.

FIGS. 3A and 3B show that, mechanically, a device D (one of the devices D1 to D4) comprises a base plate 1, on which is mounted a block of generally pyramidal shape, made of a synthetic material such as for example the two-component curing adhesive called araldite (registered trademark).

The pyramid is doubly truncated. On one side, it is truncated at an intermediate level 21, where are provided orifices suitable for receiving the lamp bases L1 and L2, which are then mounted perpendicular to the flat face 1. At the top, the pyramid is truncated at one level upper 22, where terminals B1 and B2 appear which will be found later.

Between the two lamps L1 and L2, for example on the intermediate level 21, is mounted a column 3, pluggable electrically and mechanically by studs such as 31 and 32 on the block 2. On the side of the lamp L1, this column 3 houses a photodetector 30, which is brought into contact with the illuminating part of this lamp. The mounting is preferably carried out so that this detector is very insensitive to other ambient light sources which may arise.

Finally, the base plate 1 includes, for example at an angle, bean-shaped fixing holes such as 11, 12, 13 and 14.

It should be noted in passing that the replacement of a complete device in an indicator box is made particularly simple, since it suffices to unhook it from the pins which cooperate with these orifices 11 to 14, after having disconnected the supply of the terminals B1 and B2 .

The lamps L1 and L2 are for example fluorescent lamps of the type with ballast and incorporated regulator, such as the lamps known in France under the name "Fairy". It turned out that a single 9 watt lamp could be enough to light a standardized airport box.

You can switch to 18 watt lamps if necessary, by modifying the current transformer.

FIG. 4 shows the electrical diagram of a device D according to the invention.

The terminals B1 and B2 are terminals leading to the primary winding P of a current transformer TC, with its magnetic circuit CM.

This receives a main secondary winding S, which will be used to power the lighting. This primary winding S first receives in parallel a capacitor 50. This is followed in parallel by two high-voltage clipping diodes mounted head to tail, 51 and 52.

After that, there is an inverter I. In its rest position, this inverter I closes the circuit on a lamp L1. In its working position, it closes it on the L2 lamp.

The lamp L1 receives in parallel a resistance R10 of high value. And it is coupled to the photodetector 30 already mentioned.

An auxiliary secondary winding SA, provided in parallel with a surge suppressor 70, supplies a rectifier bridge 80, the outputs of which are provided in parallel with filtering produced by capacitor 91 and resistor 92.

The output of this is used to supply an electronic control assembly, the input of which is defined by the photodetector 30.

This one, which is here phototransistor, has its collector connected to the positive terminal by a resistor 101, while its emitter joins the base of a transistor 102 whose emitter is grounded and whose collector joins the positive line by resistance 103.

A first time constant is defined on the output of transistor 102 by resistor 104 and capacitor 10.7.

In parallel on the resistor 104 are mounted in series a diode 105 and a resistor 106, the cathode of the diode being on the side of the collector of the transistor 102. The resistor 104 is of significantly higher value than the resistor 106. This allows, when the phototransistor 30 finds that the lamp L1 does not light up, this information is inhibited for a time corresponding to a time at least equal to the nominal duration of ignition of the lamp. In practice, the ignition time of a lamp of this kind being approximately 2 seconds, the time constant applied to the detection is of the order of 10 seconds for example.

Of course, in the opposite direction, the time constant is much lower.

Thus, when the lamp L1 has stopped lighting or has not lit for 10 seconds, the voltage available across the capacitor 107 rises, to be transmitted through a threshold device 108 consisting for example of a Zener diode at a Darlington power stage 110. This actuates via a resistor 111 a relay 120, which receives in parallel a capacitor 112. The relay 120 changes the state of the switch I, at the same time as '' it closes a contact 121, which ensures the self-maintenance of the relay.

The tilting of the inverter has the effect of using the lamp L2, in place of the lamp L1.

Those skilled in the art will understand that, when the relay 120 is in operation, the consumption of the electrical control assembly will have increased.

So that, seen from terminals B1 and B2, the consumption is the same in both cases, it is planned to put in parallel on the lamp L1 a resistance R10 of high value, suitable for consuming an energy which corresponds substantially to the overconsumption of the electrical control assembly when the L2 lamp is in use.

When it is necessary to restore the operation of the lamp L1, it is possible to intervene by any means known to those skilled in the art to return the relay 120 to its resting state (power interruption in particular).

In a particular embodiment, the terminals B1 and B2 of the current transformer are supplied by an effective current of 6.6 Amperes. Secondary S supplies the nominal current of the lamp used (9 watts or 18 watts in the examples concerned) at a voltage of approximately 220 volts. This corresponds to a current transformer having a high transformation ratio, of the order of about 70, note that if the value of the effective primary current is varied, this value being able to be modified by about 20%, this transformation ratio will vary. For its part, the power of the transformer is between 10 and 100 VA, preferably between 20 and 50 VA.

Thus, quite unexpectedly, it has been possible to use lamps comprising a fluorescent tube and its supply members, integrated in the same glass, while retaining satisfactory operation.

The Applicant currently believes that this is first of all due to the use of clipping diodes 51 and 52, which are for example of the ESM.111.330 type. Indeed, when the two lamps fail, these diodes nevertheless ensure, by their characteristics, the consumption of energy comparable to that consumed by one of these lamps in operation. This preserves the proper functioning of the devices integrated into the other boxes.

Things seem to be further improved when the capacitor 50 is placed in parallel on the diodes 51 and 52. This capacity can then be determined so that one obtains an overvoltage characteristic by resonance, on the part rising of the resonance curve at 50 Hertz of the assembly (or any other network frequency used). In fact, the voltage supplied to the secondary decreases very quickly as soon as the secondary load increases, which has the effect of accelerating the priming of the fluorescent tube. In addition, in open circuit, that is to say when the two lamps fail, the current in the clipping semiconductors is minimum, when the secondary voltage reaches the clipping voltage. It is thus ensured that the diodes 51 and 52 can simulate the presence of the lamps L1 and L2, without it being necessary to give them excessive current dissipation characteristics.

The invention thus makes it possible to improve the reliability of lighting the light boxes, while reducing their electrical consumption for equivalent lighting (we go from twice 45 VA to 20 VA). A secondary advantage is the reduction of the power of the emergency unit necessary to supply all the caissons of an airport, when the public electrical network does not work.

With regard to maintenance, it was noted above that the exchange of a device according to the invention is particularly simple.

It has also been found that a simple visual examination makes it possible, for technicians with an experienced eye, to detect whether an indicator box is operating on its normal lamp or on the emergency lamp. This detection can be further facilitated if the glass of the emergency lamp is lightly colored, for example by affixing thereto a colored sticker.

We will now return to FIG. 2. The boxes Ci1 to CI4 equipped with the devices according to the invention are provided in a suitable number to correspond to the operating voltage of the low voltage secondary SBT of the medium voltage / low voltage transformer.

Seen from the outside, the device according to the invention therefore functions like those of the prior art, which is another advantage.

Claims (10)

1. A lighting system including a current transformer whose secondary winding feeds at least one lamp and whose primary winding is intended to be connected in series with the primary windings of the current transformers of other, similar lighting systems, thereby constituting a portion of the secondary circuit of a medium tension/low tension transformer whose primary winding is in turn connected in a regulated current loop, the lighting system being characterized in that:

the lamp is a fluorescent lamp (L1, L2) whose trig- gering/regulation components are likewise powered by the secondary winding (S) of the current transformer (TC); and

in that the secondary winding (S) of each current transformer is provided in parallel with clipping members (51, 52) suitable, when the associated lamp fails, for consuming a substantial fraction of the nominal energy required by the lamp, thereby conserving the flow of nominal current to the primary windings of the other current transformers.

2. A system according to claim 1, characterized in that the clipping members are constituted by two high tension clipping diodes (51, 52) connected head- to-tail in series.

3. A system according to claim 1 or 2, characterized in that a tuning member (50) is provided in parallel with the secondary winding of the current transformer in order to provide a surge characteristic by resonance.

4. A system according to claim 3, characterized in that said surge characteristic by resonance (50) is adjusted so that the alternating secondary voltage as provided falls off very rapidly when the secondary load increases, thereby accelerating triggering of the fluorescent lamp, and so that the current flowing through the tripping members becomes very low once the secondary voltage reaches the clipping value.

5. A system according to claim 3 or 4, characterized in that the tuning member (50) comprises a capacitor.

6. A system according to any one of claims 1 to 5, characterized in that each lighting system comprises two lamps (L1, L2) alternatively connected by a changeover switch (I) to the secondary winding (S) of the current transformer, and switching means (101, 120) which react to non-illumination (30) of a first lamp (L1) for a period of time greater than its triggering period by actuating the changeover switch (1) in order to put the second lamp (L2) into operation.

7. A system according to any one of claims 1 to 6, characterized in that it includes a base plate (1) provided with oblong fixing openings (11-14), and supporting a block (2) of overmolded synthetic material having an intermediate level (21) in which the, or each, lamp is mounted, and a top level (22) through which the terminals (B1, B2) of the primary winding of the current transformer emerge, with the electronic circuits of the transformer being embedded in said block (2).

8. A system according to claim 7, taken in combination with claim 6, the system being characterized in that the switching means comprise a photodetector (30) received in a column (3) removably mounted on said block and suitable for bringing the photodetector substantially into contact with the illuminating portion of the first lamp.

9. A device according to any preceding claim, characterized in that the, or each, lamp (L1, L2) is of the type having an incorporated trigger circuit and ballast.

10. A system according to any preceding claim, characterized in that the current transformer (TC) has a power lying in the range 10 VA to 100 VA, and preferably the range 20 VA to 50 VA.

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