FR2770939A1 - SPARKLING DEVICE FOR THE PROTECTION OF ELECTRIC LINES AND / OR ELECTRICAL APPLIANCES AGAINST TEMPORARY OVERVOLTAGES - Google Patents

Abstract

The present invention relates to a spark gap device for protecting electrical lines and / or electrical appliances against temporary overvoltages, comprising two electrodes (150) carried by respective tabs (110), characterized in that at least one of said tongues (110) is made of a deformable material so that the distance between the electrodes (150) is extended during the development of an arc therebetween.

Description

I The present invention relates to the field of protection devices

  power lines and / or electrical devices against

temporary overvoltages.

  The present invention relates more precisely still to a device forming a lightning arrester with a high energy absorption capacity. Most of the overvoltage protection devices hitherto proposed are formed on the basis of a varistor or a spark gap,

or even a combination of these.

  Nowadays only spark gaps are compatible with a

small footprint.

  However after ignition of the spark gap, a follow-up current which is very difficult to extinguish, is often generated, especially after absorption of a

significant lightning energy.

  Different solutions have already been proposed to try to remedy

to this disadvantage.

  On this point, for example, reference may be made to the documents: FR-A-2 293 050 which describes an arc separation device comprising two horns equipped at the end of an arc extinguishing chamber in the form of a tube slots whose walls are made of a material capable of releasing a gas to exert a deionizing action on an arc path, and in which helical or annular auxiliary electrodes are placed, FR-A-676 756 which describes a protection device comprising two electrodes kept apart from each other by means of a perforated insulating plate and in which the interruption of a current is ensured by means of at least one fuse circuit breaker, DE-A- 624431 which describes a spark gap comprising two horns formed by alternating electrically conductive areas, for example copper, and weakly conductive areas, for example carbon or nickel chrome, US-A-1483540 which describes a spark gap comprising c ornaments coated with a conductive oxide suitable for being transformed into a different oxide of greater electrical resistance, by a rise in temperature, DE-A-184505 which describes a spark gap comprising two horns the base of which is made of a good conductive material and the ends of which are formed from a more resistant material, DE-A-2 513 242 which describes a spark gap comprising two horns equipped with an openwork case which contains a material susceptible to vaporization, US-A-2 608 599 which describes a spark gap comprising two electrodes made of a material capable of generating a gas under the effect of an arc and which diverge between them so that the generated gas blows said arc, and FR-A-2 503 471 which describes a spark gap composed of two horns

  made of or coated with arc-extinguishing materials.

  However, none of these known solutions gives completely

  satisfaction, especially under strong current.

  In general, it is therefore necessary to operate the network protections to ensure immediate power cut, which is not good for

continuity of service.

  The present invention now aims to propose new means with high energy absorption capacity and suitable for

  allow a natural extinction of a current immediately.

  This object is achieved in the context of the present invention by means of a spark gap comprising two electrodes carried by respective tongues, in which at least one of the tongues is made of a deformable material so that the distance between the electrodes is

  elongated when developing an arc between them.

  According to another advantageous characteristic of the present

  invention, the two tongues are made of deformable material.

  According to another advantageous characteristic of the present invention, the device comprises means capable of ensuring the passage of current, in parallel with the tongues, between connection terminals and

  the electrodes, at least after deformation of the tongues.

  According to another advantageous characteristic of the present invention, provision is made for arc extinguishing means opposite the interval

defined between the two electrodes.

  Other features, purposes and advantages of this

  invention will appear on reading the detailed description which follows and

  with reference to the appended drawings, given by way of nonlimiting examples and in which: - FIG. 1 represents a view in longitudinal section of a device according to a first embodiment of the present invention, in the rest position, - Figure 2 shows a similar view of the same device in a second position, after deformation of the electrode support tabs under the effect of an arc, - Figure 3 shows a cross-sectional view of the same device, - Figure 4 shows a view in longitudinal section of a device according to a second embodiment of the present invention, in the rest position, - Figure 5 shows a view in longitudinal section of a device according to a third embodiment of the present invention, in the rest position, and - Figures 6 and 7 show similar views of the same device respectively in working positions at low current and high current. We see in Figures 1 to 3 attached a spark gap according to the present invention which comprises a housing 100 housing two

  tabs 110 which each carry an electrode 150.

  The housing 100 can be the subject of numerous embodiments.

  Preferably the housing 100 is adapted to allow attachment

  on a support rail, such as a standard DIN rail.

  To this end, the housing 100 preferably has a generally parallelepiped shape. More specifically, the housing 100 preferably has a generally flattened shape comprising on a longitudinal edge 101, a protuberance 102 whose outline is itself generally parallelepiped. The two main faces of the housing 100 are visible in the figure

  3, under the references 103 and 104.

  The housing 100 is advantageously made of electrically insulating material. Preferably the housing 100 is made of, or coated with, self-extinguishing material, that is to say a material capable of generating a gas promoting the extinction of the arc when this material is

licked by an electric arc.

  The tongues 110 are preferably symmetrical with respect to a median plane P perpendicular to the main faces 103, 104 and forming

  itself plane of symmetry for the outgrowth 102.

  The tabs 110 are made of electrically conductive material. According to the particular and nonlimiting embodiment illustrated in FIGS. 1 to 3, each tongue 110 is formed from three sections 112, 114

and 116 generally rectilinear.

  The first two sections 112 are coplanar and adjacent to the second longitudinal edge 105 of the housing 100, that is to say the one opposite the protrusion 102. They are adapted to serve as a connection to the

  lines or electrical equipment to be protected.

  The second sections 114 converge together towards the center of the

  housing 100, from the internal end of the above-mentioned sections 112.

  Finally, the third sections 116 extend the second sections 114 and diverge between them, away from said second sections 114. These third sections 116 point in the direction of the angles of the projection 102, at rest. By way of nonlimiting example, at rest, the third sections 116 typically form an angle of

around 60 [.

  The third sections 116 each carry an electrode 150, on their facing surfaces. Thus the electrodes 150 are inclined to each other, in the form of a dihedral, at rest. More precisely still, the electrodes 150 diverge from one another, from the point of birth of

  the arc, ie from their end close to the arrival of the current.

  Preferably each electrode 150 is formed of a circular patch fixed on the third section of a tongue 110 by any suitable means, for example by welding, riveting (as illustrated

  in the appended figures) or any equivalent means.

  The electrodes 150 must of course be made of an electrically conductive material, resistant to an electric arc, this is to

  say having good resistance when subjected to an electric arc.

  The electrodes 150 can be made of a material to

  arc extinction, as indicated previously for box 100.

  Alternatively, a deposit of arc extinguishing material can

  be applied directly to the electrodes 150.

  Of course the geometry of the tongues 110 and electrodes 150 illustrated in the appended figures must in no way be

considered limiting.

  It will also be noted on examining Figures 1 to 3 that the spark gap

  further includes two rigid supports 160 for the tabs 110.

  These are preferably rectilinear, mutually parallel and

  symmetrical with respect to the aforementioned median plane P.

  The supports 160 can also be made of, or coated

of, arc extinguishing material.

  The base of the supports 160 is fixed to the second longitudinal edge

of housing 100.

  Their apex 162 serves to support the second section 114 of an associated tongue 110, in the vicinity of the connection zone between the second and third sections 114/116. To this end, the apex 162 of the supports 160 is preferably oblique with respect to the median plane P, according to an obliquity which coincides with that of the second sections 114, at rest. In addition, the housing 100 illustrated in the appended figures includes a spark arrester 170, which surrounds the second and third

  sections 114, 116 as well as the electrodes 150 and the supports 160.

  Preferably this chimney 170 is formed of two main walls 172, 174 planes, parallel to each other, which extend the side walls of the projection 102. The chimney 170 is advantageously made of, or coated with, arc-extinguishing material. Of course the walls 172, 174 are provided at their base opposite the projection 102, with cutouts 173 allowing the passage of the second sections 114 with freedom of deformation, as is

will explain it later.

  In addition, the housing 100 includes vents 106 designed to allow the escape of the gases generated inside the housing 100 under the effect of an electric arc. By way of nonlimiting example, such vents can be provided in the lateral walls of the projection 102, parallel to the median plane P, and perpendicular to the plane

longitudinal 101.

  Thus, at rest, the two electrodes 150 are placed in the air.

  The operation of the spark gap device which has just been described is

basically the following.

  In the event of an overvoltage between the terminals of a line or of a device to be protected, fitted with such a protection device connected in parallel, a

  priming occurs between the electrodes 150.

  This arc is then supplied by the current on. The angle formed by the two electrodes 150 facilitates the upward stretching of the arc, created by the electrodynamic forces, that is to say in approach of

the projection 102 of the housing 100.

  Consequently the resistance of the arc increases and causes a

  reduction of the current immediately and thus favors its extinction.

  Furthermore, in the context of the present invention, the tongues 110 are advantageously made of a material which is deformable under the effect of an arc developed between the electrodes 150. Thus the electrodes 150 are further apart automatically when an electric arc appears

  between them, which further favors the extinction of the current immediately.

  It can thus be seen on a comparative examination of FIGS. 1 and 2, that under the effect of an electric arc developed between the electrodes 150, the spacing between the base of the electrodes 150 changes from a small value el at rest (see Figure 1) at a much higher e2 value when

  the appearance of an electric arc (see Figure 2).

  Possibly the deformation of the tongues 110 (spacing when an electric arc appears) may be due to the electrodynamic forces developed during the appearance of such an arc. The return of the tongues 110 in the rest position can be obtained by virtue of the intrinsic elasticity of the tongues 110 or also by means of additional elastic return means, such as calibrated springs, which urge the tongues at the level of the second sections 114, towards their

  rest position illustrated in Figure 1.

  Preferably, however, the tongues 110 are deformed in spacing under the effect of the heating produced in the tongues following the current passing through them to reach the electrodes 150. And moreover the tongues 110 are preferably adapted to return to position of rest, at room temperature, thanks to their

intrinsic properties.

  To this end, the tabs 110 can for example be formed from

  heat sensitive bimetallic strips or shape memory material.

  The use of bimetallic strips or of shape memory material makes it possible to improve the deformation of the tongues 110, from the close rest position illustrated in FIG. 1, to a separated position during the appearance of an electric arc illustrated in Figure 2, with reminder

  automatic to the rest position when the said arc is removed.

  It will be noted that the deformation of the tongues 110 is effected essentially at the level of the second sections 114 of the tongues

  , as seen in the comparative examination of Figures 1 and 2.

  Furthermore, as can be seen in the appended figures, preferably the housing 100 is provided on its internal surface with a gas deflector 190 placed opposite the interval defined between the two electrodes 150. More precisely, this deflector 190 is placed on the side of the electrodes 150 towards which the arc is pushed. Thus according to the particular embodiment illustrated in the appended figures, the deflector 190

  is placed on the internal surface of the projection 102.

  The deflector 190 is advantageously made of, or coated with,

arc extinguishing material.

  As described above for the housing 100, the electrodes 150 and the supports 160, such an arc extinguishing material is not consumed

  not but projects a substance which promotes the extinction of the arc.

  There is illustrated in FIG. 4 an alternative embodiment in which the means previously described are fully found and which is distinguished from this embodiment of FIGS. 1 to 3 only by the fact that according to FIG. 4, the spark-gap device comprises in addition to a braid of flexible electrically conductive material, placed in parallel

of each tab 110.

  More precisely, the braids 200 are placed between the first sections 112 and the third sections 116 of the tabs 110. The braids 200 can be fixed to these elements, with electrical contact, by any suitable means, such as for example by welding or

mechanical fixing.

  Thus in the event of an overvoltage, the braids 200 directly pass the current, from the connection section 112, to the

electrodes 150.

  Such braids 200 have a resistance lower than that of the shape memory alloy or bimetallic strip making up the tongues 110 and thus avoid the passage of a large current through the deformable material of the tongues 110 and consequently avoid a

  significant heating of these.

  There is shown in Figures 5 to 7 appended another alternative embodiment on which there is a housing 100 which houses two rigid supports 160, two deformable tabs 110 and two

electrodes 150.

  The whole is preferably symmetrical with respect to the median plane P,

at rest.

  The supports 160 are made of electrically conductive material, for example copper. They participate in the flow of the current

developing the arc.

  Each support 160 preferably comprises four sections 1602, 1604, 1606 and 1608. The first two sections 1602 are coplanar and adjacent to the second longitudinal edge 105 of the housing 100, that is to say the one opposite to the protrusion 102. They are adapted to serve as a connection to

  lines or electrical equipment to be protected.

  The second sections 1604 converge together towards the center of the

  housing 100, from the internal end of the above-mentioned sections 1602.

  The third sections 1606 extend the second sections

  1604. They are preferably parallel to each other.

  Finally, the fourth sections 1608 are coplanar with one another and housed in the projection 102. They diverge from each other away from

  their connection zone on the third sections 1606.

  The tabs 110 have the general shape of an "L" with two

branches 1100 and 1102.

  They are placed on the inside of the supports 160.

  A first branch 1100 of the tongues is pressed against the external surface of the fourth sections 1608. The first branch 1100 of the tongues can be connected to this fourth section by all

  suitable means, for example by welding or riveting in 1609.

  The second branches 1102 extend parallel to each other,

between the two supports 160.

  The device illustrated in Figures 5 to 7 further comprises a spacer 210 of electrically insulating material interposed between the

two tabs 110.

  The spacer 210 advantageously has the shape of a T. The transverse head 212 of this spacer 210 rests on the

outer surface of the tabs 110.

  The core 214 of the spacer 210 is disposed between the tongues 110. The electrodes 150 are placed on the free ends of the

  second branches 1102, between the second sections 1604.

  Also here again, the tongues 110 are made of a deformable material when an electric arc appears, for example under the effect of electrodynamic forces, or even thanks to bimetallic or shape memory properties, with elastic return automatic in

rest position.

  The operation of the device illustrated in Figures 5 to 7 is as follows. At rest the tabs 110 are pressed against the insulating spacer 210. This thus defines the air gap between the electrodes

  and therefore a relatively constant ignition voltage.

  Upon the appearance of a low energy overvoltage corresponding to a current of moderate amplitude between the supports 160, an ignition

  occurs between the electrodes 150 and an arc is developed between them

  this. As can be seen on the comparative examination of FIGS. 1 and 2, the electrodes 150 are separated by virtue of the deformability properties of the

  tabs 110, to promote extinction of the arc by stretching.

  After extinction of the arc, the tabs 110 automatically bring the electrodes 150 back to the rest position illustrated

in Figure 5.

  However, in the event of a high energy overvoltage, and therefore of a high current between the electrodes 150, the electrodynamic forces and / or the heating of the tongues 110 are greater so that the deformation of the tongues 110 is more pronounced. The electrodes 150 then come to rest on the sections 1604 of the supports 160, as

seen in Figure 7.

  In this provisional position, the supports 160 ensure the passage of current to the electrodes 150, in parallel with the tongues 110. This arrangement makes it possible to preserve the tongues 110. The supports 160 then play a role comparable to that of the braids 200

  according to the embodiment of Figure 4.

  Note also that according to the embodiment illustrated in Figures 5 to 7, the deflector 190 placed opposite the defined interval

  between the electrodes 150, is formed by a crenellated plate.

  This plate 190 thus forms a baffle which can proceed essentially by mechanical effect, that is to say elongation of the arc,

  to participate in the extinction of it.

  Preferably, however, the plate 190 is also produced in

  self-extinguishing material, to reinforce this arc extinguishing effect.

  According to yet another alternative embodiment, the means placed opposite the interval defined between the electrodes 150, to participate in the extinction of the arc, can be formed by magnetic means, for example permanent magnet or electric coil, proceeding

  essentially by lengthening it.

  The spark gap devices according to the present invention make it possible to cut currents which can reach from a few kA to

  at least about 50 kA, form 10/350.

  Of course the present invention is not limited to the embodiments previously described, but extends to all variants

conform to his spirit.

Claims (26)

  1. A spark gap device for the protection of electric lines and / or electric devices against temporary overvoltages, comprising two electrodes (150) carried by respective tongues (110), characterized in that at least one of said tongues ( 110) is made of a deformable material so that the distance between the electrodes (150) is lengthened during the development of an arc between them. 2. Device according to claim 1, characterized in that the   two tongues (110) are made of deformable material.   3. Device according to one of claims 1 or 2, characterized by the   fact that it comprises means (200; 160) capable of ensuring the passage of current, in parallel with the tongues (110), between connection terminals (112; 1602) and the electrodes (150), at least after deformation of the tongues (110).   4. Device according to one of claims 1 to 3, characterized by the   fact that it includes arc extinguishing means (190) opposite   the interval defined between the two electrodes (150).   5. Device according to one of claims 1 to 4, characterized by the   the fact that the housing (100) is made of, or coated with, self- extinguishable.   6. Device according to one of claims 1 to 5, characterized by the   causes the electrodes (150) to be inclined to each other in the form of a dihedral at rest.   7. Device according to one of claims 1 to 6, characterized by the   that the electrodes (150) are made of, or coated with, a arc extinguishing material.   8. Device according to one of claims 1 to 7, characterized by the   that it further comprises two rigid supports (160) for the tabs (110) at rest.   9. Device according to claim 8, characterized in that the supports (160) are made of, or coated with, arc extinguishing material.   10. Device according to one of claims 1 to 9, characterized by the   includes a spark arrester chimney (170), which surrounds the minus the electrodes (150).   11. Device according to claim 10, characterized in that the   chimney (170) is formed of, or lined with, arc-extinguishing material.   12. Device according to one of claims 1 to 11, characterized by   the fact that the housing (100) has vents (106) designed to allow the escape of the gases generated inside the housing (100) under the effect of an electric arc.   13. Device according to one of claims 1 to 12, characterized by   the fact that the tongues (110) are adapted to be deformed under the effect of electrodynamic forces developed during the appearance of an arc.   14. Device according to one of claims 1 to 13, characterized by   the fact that the tongues (110) are adapted to be deformed in spacing under the effect of the heating produced in the tongues (110) following the current passing through them to reach the electrodes (150).   15. Device according to one of claims 1 to 14, characterized by   the fact that the tongues (110) are adapted to return to the position of   rest, at room temperature, thanks to their intrinsic properties.   16. Device according to one of claims 1 to 15, characterized by   the fact that the tongues (110) are formed from bimetals sensitive to heat.   17. Device according to one of claims 1 to 16, characterized by   the fact that the tabs (110) are made of memory material form.   18. Device according to one of claims 1 to 17, characterized by   the fact that it comprises a gas deflector (190) placed opposite the interval defined between the two electrodes (150), on the side of the electrodes   (150) towards which the arc is thrown.   19. Device according to claim 18, characterized in that the   deflector (190) is made of, or coated with, arc extinguishing material.   20. Device according to one of claims 1 to 19, characterized by   the fact that it includes a braid (200) of flexible electrically conductive material, placed in parallel with each tongue (110).   21. Device according to one of claims 1 to 20, characterized by   the fact that it includes a spacer (210) made of electrically material   insulation inserted between the two tabs (110).   22. Device according to one of claims 1 to 21, characterized by   the fact that it comprises supports (160) of electrically conductive material, disposed on the outside of the tongues (110) and distant from the electrodes (150) at rest, the tongues (110) being however adapted to be pressed against the supports (160) when a high-power arc appears, so that the supports (160) ensure the passage of current to the electrodes (150), in parallel tabs (110).   23. Device according to one of claims 18 or 19, characterized   by the fact that the deflector (190) is formed by a crenellated plate.   24. Device according to claim 23, characterized in that the plate (190) forms a baffle which proceeds by mechanical effect, it is   say elongation of the arc, to participate in the extinction of it.   25. Device according to one of claims 1 to 24, characterized by   the fact that the plate (190) is made of, or coated with, self-adhesive material extinguishable.   26. Device according to one of claims 1 to 25, characterized by   the fact that it includes magnetic means, magnet or electric coil, placed opposite the interval defined between the electrodes   (150), to participate in the extinction of the arc.