FR2505051A1 - SHIELDED ELECTRICAL INSTALLATION WITH PRIMING DETECTION DEVICE - Google Patents

Abstract

The switching cells (2-6), which are arranged side-by-side, of a switching installation (1) are provided with a pressure relief flap (18-22). In the event of a pressure rise inside the cells, caused by a fault arc, the corresponding pressure relief flap (18-22) opens. In order to confirm the occurrence of such a fault arc, a light barrier (23) is provided, having a radiation source (24) and a photoelectric component (26). The beam (25) emitted by the radiation source (24) passes through the movement path of the pressure relief flaps (18-22) so that the beam (25) is interrupted by an opening pressure relief flap (18-22). The interruption in the beam (25) triggers the photoelectric component (26) and generates a signal which is supplied, after amplification where applicable, to a switch tripping device (27) which opens a main switch (7). A switching installation having a multiplicity of switching cells (2-6) arranged side-by-side can be monitored effectively using a single light barrier (23).

Description

Shielded electrical installation with ignition detection device
The invention relates to a shielded electrical installation comprising at least one closed cell, at least one element of which is moved inside the cell under the effect of the pressure increase due to priming, said element being associated with a detector. of displacement.

 Ignition detection devices are known in which, in each cell (for cells divided into several volumes, in each volume) is arranged a photoelectric element, for example a photoelectric cell or a photoresistor. The photoelectric elements react to the change in brightness caused by the ignition, and give an electrical signal transmitted to a command, which will cut the relevant part of the installation.

 In this regard, reference is made to Swiss patent No. 370158, to the German utility model No. 7221753 and to the published German patent application No. 1908785.

 These known solutions require a large number of photoelectric elements, which is a technical as well as an economic drawback, especially for installations comprising several cells each divided into several volumes.

 In addition, the control of the operating capacity of these known embodiments is difficult, because it requires a flash of sufficient brightness. On the other hand, these control devices must be designed in such a way that they do not react in the event of lightning flash, daylight or normal lighting. However, nuisance tripping due to stray light cannot be easily avoided.

 For another type of control device, also based on a modification of the brightness due to ignition, only one photoelectric element is used, which communicates by light conductors with the volumes to be monitored (Model German Utility No. 8019228).

 For this, a single photoelectric element is sufficient, but it is necessary to provide a number of light conductors corresponding to the number of volumes to be monitored. The technical and financial effort is therefore also considerable. This type of control device therefore has essentially the same drawbacks as the other solutions described above.

 By the German utility model No. 7520784, it is known to directly couple the closing energy accumulator of a short-circuiting device and to the earth with the expansion valve of the corresponding cell.

 The increase in pressure created by the priming causes the opening of the expansion valve, which frees the energy accumulator which allows the switching on of the short-circuiting device and to earth. This control device has the advantage of reacting to an increase in pressure and not to a change in the brightness which is difficult to detect, but the disadvantage of this solution lies in the fact that due to the direct coupling between the storage accumulator. energy of a short-circuiting and earthing device and of an expansion valve, it can be used without difficulty only for cells or volumes comprising such a device.

 This drawback is avoided for the installation described in the German utility model No. 7505439 by the fact that an expansion valve reacting to a rise in pressure inside the cell is mechanically coupled to an inserted switch contact. in the circuit breaker trip circuit. The opening of the expansion valve causes the contact to close, which gives an opening of the circuit breaker and therefore the separation of the corresponding part of the installation. In this case, however, it provides for each volume to be monitored, a switch contact, mechanically connected to an expansion valve, which must be inserted in the circuit-breaker tripping circuit. This represents a considerable technical load, in particular for electrical installations with several cells, where each cell is itself divided into several volumes.

 The invention aims to create an installation of the type mentioned above in which ignitions are detected and eliminated quickly and reliably, and comprising the minimum of equipment.

 The subject of the invention is a shielded electrical installation comprising at least one closed cell, at least one construction element of which is displaced under the effect of the pressure increase inside the cell due to priming, said element being associated with a displacement detector, characterized in that the detector comprises at least one photoelectric device comprising a radiation source and a photoelectric element intended to receive the light beam emitted by said source, said construction element being arranged so that during its displacement due to the increase in pressure, it is introduced into this light beam.

 The photoelectric device is triggered indirectly by the increase in pressure in the monitored volume due to priming, and reacts as soon as a building element moved by the increase in pressure, for example a pressure relief valve, enters the light beam emitted by the radiation source. The physical quantity used, which is the increase in pressure, can be perfectly measured and distinguished from disturbing quantities, so that nuisance tripping is avoided in most cases.

 Priming is detected quickly using simple and reliable means. The reaction of the photoelectric device creates a signal which can be used to immediately trigger a device which will isolate the relevant part of the installation.

 The radiation source and the photoelectric element are arranged in a part of the installation which is normally inaccessible, for example above the cells. As soon as people or even animals enter this area and thus interrupt or reflect the light beam of the photoelectric device, the latter reacts. Thus this photoelectric device is used, in addition to the detection of initiations, also to protection against work accidents and against unintended and annoying interruptions of service.

 For an installation comprising several juxtaposed cells, each having a movable element, a single photoelectric device makes it possible to monitor all the cells, or volumes aligned in the direction of the light beam, provided that all the movable elements are arranged by increasing pressure in such a way that they can be introduced into the path of the light beam. Thus, even installations comprising numerous cells, themselves divided into several volumes, can be perfectly monitored by relatively simple means.

 To avoid the possible influence of disturbing lights, an infrared radiation source is preferably used, which can, if necessary, emit a modulated light beam. This can be advantageous, in particular, when the photoelectric device reacts to the reflection of the light beam on an element introduced in its path.

An exemplary embodiment of the invention is described below with reference to the accompanying drawing in which:
FIG. 1 is an overall diagram of an electrical installation, with several cells, fitted with a device for detecting initiations.

 Figure 2 shows schematically a side ear cell.

 The electrical installation designated by 1 comprises several juxtaposed cells 2, 3, 4, 5, 6.

 In cell 2 there is a main switch 7, which connects an incoming cable 8 to a bus bar 9 which passes through all the cells. In the other cells 3 to 6 there are disconnectors 14 to 17, which are located between the bus bar 9 and each of the outgoing cables 10 to 13. Each of the cells 2 to 6 is provided with an expansion valve 18 to 22 located on top of the cell. This valve opens upwards, in the direction of arrow A, when the pressure in the cell rises due to priming. Figure 1 shows the valves 19 and 21 open. So far, the installation has essentially been of a conventional type of construction.

 The monitoring of cells 2 to 6 concerning the priming is ensured by a photoelectric device generally designated by 23 which, in the embodiment described in the form of a light barrier.

 This device 23 includes a radiation source 24 which emits a light beam 25. The radiation source 24 can produce visible light or invisible infrared or ultraviolet radiation. A radiation receiver 26 in the form of a photoelectric element, is arranged at a certain distance from the radiation source 24. This photoelectric element 26 may for example be a photoelectric cell or another suitable element. The amplifier possibly necessary for the amplification of the signal produced by the photoelectric element 26 is not shown. A conventional trigger device 27 is connected to this amplifier or else to the photoelectric element 26, which opens the main switch 7 on reception of a corresponding signal.

The priming de-detecttoD device works as follows
Priming in a cell, for example in cell 3, causes a considerable increase in the pressure inside the closed cell 3. From this increase in pressure results the opening towards the outside of the expansion valve 19. During this movement, the valve crosses the light beam 25 and interrupts it.

The photoelectric element 26 reacts to this interruption of the light beam 25 and produces a signal, which after amplification, is brought to the trigger device 27. The latter opens the main switch 7 and thus cuts the supply to the fault. in the cell concerned 3.

 The main switch 7 is opened relatively quickly after the onset of ignition. The expansion valves take approximately 10 ms to open towards the outside and thus interrupt the light beam 25. The time elapsed between the reaction of the photoelectric element 26 in the event of an interruption of the beam, and the triggering of the main switch 7 is of the order of 10 to 30 ms.

 As a rule, the cells are divided into several volumes, which is shown schematically in Figure 2, which shows a cell for example cell 3 in side view. The partitions 28 and 29 divide the interior of the cell 3 into a volume 30 of the circuit breaker, a volume 31 of the busbar as well as a cable outlet volume 32 in which the cable boxes 33 are placed. Each of these closed volumes 30, 31, 32 is provided with an expansion valve 19a, 19b, 19c.

 The strikes which may appear in these volumes 30, 31, 32 are detected by three photoelectric devices 23a, 23B or 23c which are designed in the same way as the control 23 explained with the aid of FIG. 1.

 In FIG. 2, only the radiation sources 24a, 24b, 24c of these devices 23a, 23b and 23c are shown.

 As shown in FIG. 1, the volumes 30 of the circuit breakers, the volumes 31 of the busbars as well as the volumes 32 of the cable feeders of the different cells 2 to 6 are aligned in the direction of the light beam of the corresponding photoelectric control 23a, 23b or 23c so as to allow the control of similar volumes of cells 2 to 6 by a single photoelectric control for each type of volume.

 In the event of ignition, in one of the volumes 30, 31, 32 of a cell 2 to 6, the corresponding expansion valve 19a, 19b or 19c opens and thus interrupts the light beam of the photoelectric control 23a, 23b or 23c corresponding. Thus the affected part of the installation is cut as described in FIG. 1, by opening the main switch 7.

 A single photoelectric device 23 or 23a, 23b, 23c per series of cells 2 to 6 or else per closed volume 30, 31, 32 of cells 2 to 6 thus makes it possible to effectively monitor an installation comprising a large number of cells.

 The installation shown in the figures and its ignition detection device can, of course, have many variants.

 Thus, for example, it is possible to provide, in addition to or in place of the relief valves 18-22, other elements, for example in the form of a shutter, which would be introduced into the light beam 25 in the event of an increase in the pressure at inside the cell, and which would therefore interrupt the light beam 25. On the other hand, it would be possible to provide the expansion valves 18-22 with such an element, for example a shutter, which would serve to interrupt the light beam 25 at when the expansion valves open.

 It is naturally also possible to use the signal produced during the interruption of the light beam 25 by the photoelectric element 26 for the triggering of any suitable device, for example a short-circuiting and grounding device. .

 Instead of designing the photoelectric device 23 as above, as a light barrier reacting to the interruption of the light beam 25, it is also possible to provide a photoelectric device 23 reacting to the reflection of the light beam by a flap or another suitable item. For such a solution, the photoelectric element 26 is generally disposed near the radiation source 24. To avoid stray light effects on a photoelectric device 23 reacting to the reflected light beam, preferably used an infrared radiation source 24. If necessary, a radiation source 24 can be used which produces a modulated light beam 25.

Claims (10)

1 / Armored electrical installation comprising at least one closed cell, at least one construction element of which is displaced under the effect of the pressure increase inside the cell due to priming, said element being associated with a detector displacement, characterized in that the detector comprises at least one photoelectric device (23) comprising a radiation source (2) and a photoelectric element (26) intended to receive the light beam (25) emitted by said source , said construction element (18 to 22) being arranged so that during its displacement due to the increase in pressure, it is introduced into this light beam (25). 2 / electrical installation according to claim 1, having several juxtaposed cells each of which comprises at least one construction element displaced during an increase in pressure, characterized in that said elements (18 to 22) of cells (2 to 6) are turned towards the light beam (25) emitted by the source (24) and can be introduced therein. 3 / electrical installation according to one of claims 1 and 2, characterized in that each of the cells (2 to 6) is divided into at least two separate volumes (30, 31, 32), each of these volumes comprising an element construction (19a, 19b, 19c) moved during an increase in pressure inside the cell, a photoelectric device (23a, 23b, 23c) being assigned to each volume (30, 31, 32) and triggered by the reaction of the building element (19a, 19b, 19c). 4 / electrical installation according to claim 3, characterized in that the movable construction elements (19a, 19b, 19c) of the corresponding volumes (30, 31, 32) of the juxtaposed cells (2 to 6) are aligned on each other and oriented towards the 3rd light beam (25) emitted by the corresponding source (25a, 24b, 24c). 5 / electrical installation according to one of claims 1 to 4, characterized in that the construction element moved during the increase in pressure is a pressure relief valve (18 to 22) which opens outwards . 6 / Electrical installation according to one of claims 1 to 5, characterized in that the photoelectric device (23) forms a light barrier reacting to the interruption of the light beam (25) by a building element (18 to 22 ) movable.  7 / Electrical installation according to one of claims 1 to 5, characterized in that the photoelectric device (23) reacts when the light beam (25) is reflected on a building element (18 to 22) which can be introduced in its path. 8 / electrical installation sleon one of claims 1 to 7, characterized in that said source is infrared radiation (24). 9 / Electrical installation according to one of claims 1 to 8, characterized in that the radiation source (24) emits a modulated light beam (25). 10 / Electrical installation according to one of claims 1 to 9, characterized in that it comprises at least one breaking device (7), such as a main switch, controlled by the signal emitted by the photoelectric device ( 23).