WO2005112050A1

WO2005112050A1 - Surge voltage protection device with arc-breaking means

Info

Publication number: WO2005112050A1
Application number: PCT/FR2004/000959
Authority: WO
Inventors: Michel Georges Jean Donati; Alain René Robert LAGNOUX; Vincent André Lucien CREVENAT
Original assignee: Soule Protection Surtensions
Priority date: 2004-04-19
Filing date: 2004-04-19
Publication date: 2005-11-24
Also published as: EP1743346A1; SI1743346T1; CN100578690C; ATE489712T1; ES2356608T3; DE602004030280D1; CN1914696A; EP1743346B1

Abstract

A device for protecting an electrical system against surge voltages, comprising one or more protection components (10) provided with means (20) for connecting same with said system and means (30) for disconnecting said component (10) from said system, characterised in that it comprises arc-breaking means (40) for preventing the generation of electric arcs between the disconnection means (30) and the connection means (20) when the disconnection means (30) is in an open state, wherein said arc-breaking means (40) consist of an insulating flap (41) capable of moving within the gap (11) and comprising a central portion (42) to be positioned between the disconnection (30) and connection (20) means, and side portions (43) shaped in such a way as to prevent the electric arc from bypassing the arc-breaking means (40). Electrical surge voltage protection devices are also described.

Description

OVERVOLTAGE PROTECTION DEVICE PROVIDED WITH ARC BREAKING MEANS

TECHNICAL AREA

The present invention relates to the general technical field of devices for protecting electrical installations and equipment against transient electrical overvoltages.

The present invention relates more particularly to a device for protecting an electrical installation against overvoltage comprising: - at least one protective component, provided with means for connection to the electrical installation, - a means for disconnecting the protective component from to the electrical installation, adapted to ensure the disconnection of the latter at the connection means, and capable of moving from a closed position to an open position thereby creating an interstitial space between the means of disconnection and connection means.

PRIOR ART

Protection devices for electrical installations are commonly used to protect electrical or electronic devices against overvoltages which may, for example, be generated by discharges due to lightning. These devices generally comprise an active part formed by one or more protective components, such as for example a varistor or a spark gap.

Varistors are components commonly used to protect electrical installations or equipment against transient overvoltages. When the varistors are exposed to voltages higher than a predetermined threshold value, they are likely to flow high currents and to absorb and dissipate the energy associated with the overvoltage while flowing the lightning current to the ground.

When an overvoltage occurs within the installation, the varistor undergoes a current shock which causes the component to heat up thermally. This is the reason why protection devices using varistors are generally provided with thermal disconnection means. These thermal disconnection means are intended to isolate the varistor from the electrical installation to be protected in the event of excessive heating of the protective component in order to limit the risk of fire.

The thermal disconnection means can thus be formed by a disconnection blade, welded to one of the electrodes of the varistor, and subjected to a mechanical stress tending to move it away from the corresponding electrode. Thus, when an excessive overvoltage or prolonged use causes the rupture or fusion of the weld, the disconnection blade moves away from the electrode, thus isolating the varistor from the installation to be protected.

Although they are commonly used, such devices nevertheless suffer from several significant disadvantages. Thus, after fusion or rupture of the weld, the insulation distance created between the disconnection blade and the varistor electrode is generally quite small.

Consequently, if a high amplitude overvoltage occurs, it may happen that the mechanical opening of the disconnection means is not sufficient to completely isolate the varistor from the electrical installation, an electric arc then being liable to form between the disconnection blade and the corresponding varistor electrode.

This phenomenon has the effect of significantly limiting the resistance of the protection device to high amplitude overvoltages.

To overcome this drawback, it is known to use an additional breaking device, of the circuit breaker or fuse type, which ensures the permanent interruption of the current flowing in the protection device.

Devices equipped with this additional cut-off device, if they have the advantage of being particularly safe and effective, however suffer from several drawbacks.

First of all, the caliber of the complementary cut-off device must preferably be adapted to the capacity of the varistor, which generates technical constraints and an increase in the costs of implementing the overall protective equipment.

In addition, the complementary breaking device generally ensures the simultaneous and indiscriminate isolation of all the protective components of the device, while on the contrary it is desirable to isolate only the varistors having excessive heating and to maintain the others protective components in service. STATEMENT OF THE INVENTION

The objects assigned to the invention therefore aim to remedy the various drawbacks listed above and to propose a new device for protecting electrical installations against overvoltages whose resistance to overvoltages is improved.

Another object of the invention is to propose a new device for protecting electrical installations against overvoltages which makes it possible to guarantee the individual disconnection of each protection component of the device.

Another object of the invention is to propose a new device for protecting electrical installations against overvoltages which is simple and reliable in design.

Another object of the invention is to propose a new device for protecting electrical installations against overvoltages requiring only a limited number of moving mechanical parts to obtain the connection and disconnection functions.

Another object of the invention is to propose a new device for protecting electrical installations against overvoltages which makes it possible to indicate in a reliable and instantaneous manner that a component for protecting the device is disconnected.

The objects assigned to the invention are achieved using a device for protecting an electrical installation against overvoltage comprising: - at least one protective component, provided with means for connection to the electrical installation, - A means of disconnecting the protective component from the electrical installation, adapted to ensure the disconnection of the latter at the connection means, and capable of moving from a closed position to a position of opening thereby creating an interstitial space between the disconnection means and the connection means, characterized in that it comprises arc cutting means, intended to prevent the formation of electric arcs between the disconnection means and the means connection when the disconnection means is in the open position, said arc breaking means being formed by an insulating flap, able to move at least partially within the interstitial space and comprising a central part, intended to be interposed between the disconnection means and the connection means, and lateral parts, shaped so as to prevent the circumvention of the connection means upure of arc by the electric arc.

SUMMARY OF DRAWINGS

Other features and advantages of the invention will become apparent and will emerge in more detail on reading the description given below, with reference to the appended drawings, given purely by way of non-limiting illustration, in which:

- Figure 1 illustrates, in a schematic view, a first variant of a surge protection device according to the invention provided with arc cutting means.

- Figure 2 illustrates, in a general perspective view, a preferred embodiment of the arc breaking means of the protection device according to the invention. - Figures 3a and 3b illustrate, in a schematic view, the positioning of the switching means when the varistor is in service (Figure 3a) or when the varistor is disconnected (Figure 3b).

- Figures 4a and 4b illustrate, in a schematic view, another alternative embodiment of the arc breaking means of the device and their positioning when the varistor is in service (Figure 4a) or disconnected (Figure 4b).

BEST WAY TO IMPLEMENT THE INVENTION

The overvoltage protection device according to the invention is intended to be connected bypass to the electrical equipment or installation to be protected. The expression “electrical installation” refers to all types of devices or networks liable to undergo voltage disturbances, in particular transient overvoltages due to lightning.

The overvoltage protection device according to the invention is advantageously intended to be disposed between a phase of the installation to be protected and the earth.

It is also conceivable, without departing from the scope of the invention, that the device, instead of being connected in bypass between a phase and the earth, be connected between the neutral and the earth, between the phase and the neutral or between two phases (in the case of differential protection).

The protection device according to the invention comprises at least one protection component 10 forming the active part of the arrester, intended to protect the electrical installation. In the following description, it is considered that each protective component 10 of the device is formed by a varistor, it being understood that the use of a varistor is indicated only by way of example and does not in any way constitute a limitation of the invention.

The protection device according to the invention comprises at least one varistor 10, in particular one or more varistors 10, each varistor 10 being provided with connection means 20 to the electrical installation. The varistor 10 is preferably mounted within a housing 60 capable of being in the form of a cartridge adapted to be electrically connected to a fixed base (not shown) using a first and a second connection pads 22, 23. Thus, one of the poles of the varistor 10 is connected directly to the first connection pad 22, the other pole of the varistor 10 being connected to the connection means 20, which are preferably formed by an electrode 21, for example in the form of a metal blade.

Preferably, and as shown in FIG. 1, the electrode 21 projects, for example at 90 °, from one of the substantially planar faces 10A of the varistor 10.

According to the invention, the device also comprises a disconnection means 30 associated with the varistor 10, and adapted to disconnect the latter from the electrical installation.

The disconnection means 30 is specifically adapted to ensure the disconnection of the varistor at the connection means 20, and is for this purpose capable of moving from a closed position, illustrated for example in FIG. 3a, towards an open position illustrated in FIG. 3b, thus creating an interstitial space 11 between the disconnection means 30 and the connection means 20. Preferably, the disconnection means 30 is formed by a disconnection blade 31 which, in the closed position, is welded under stress on the connection means 20, precisely on the electrode 21, preferably using a hot melt weld (not shown). One of the ends 31 A of the disconnection blade 31 then comes into electrical contact with the electrode 21 via the weld, the other end 31 B being in permanent electrical contact with the second connection pad 23.

The disconnection blade 31 is then elastically constrained between its closed position, in which it comes into contact with the electrode 21 by means of thermal welding and its open position in which the disconnection blade 31 is no longer in contact with the corresponding electrode 21.

Thus, when passing from its closed position to its open position, the disconnection blade 31, in particular the end 31A of the latter, moves away, by spring effect, from the electrode 21.

According to a particularly advantageous characteristic of the invention, the device comprises arc cutting means 40, intended to prevent the formation of electric arcs between the disconnection means 30 and the connection means 20 when the disconnection means 30 is in the open position. Thus, during the opening of the disconnection means 30, the spacing distance between the latter and the connection means 20 may not be sufficient, so that electric arcs are likely to form between the disconnection blade 31 and the corresponding electrode 21. This phenomenon then has the effect of limiting the surge withstand of the protection device. According to the invention, the arc breaking means 40 are formed by an insulating flap 41 of which at least part is able to move within the interstitial space 11.

The insulating flap 41 thus comprises a central part 42 intended to be interposed between the disconnection means 30 and the connection means 20, and lateral parts 43, shaped so as to prevent the arcing means 40 from being circumvented by the 'electric arc.

In particular, the lateral parts 43 are shaped so as to generate an increase in the distance to be traveled by the electric arc to electrically connect the electrode 21 and the disconnection blade 31.

Such a device therefore makes it possible to increase the isolation distance between the disconnection means 30 and the corresponding connection means 20, thus improving the resistance of the overvoltage protection device.

If the insulating flap 41 were only provided with a central part 42, this central part 42 could be bypassed by the electric arc, which would limit the effect of the insulating flap 41.

Advantageously, the arc breaking means 40 and the disconnection means 30 are mounted relatively in such a way that when the disconnection means 30 are opened, the latter releases the arc breaking means 40, thus allowing displacement. of these. When the disconnection means 30 is in the closed position, the insulating flap 41 advantageously bears against the disconnection means 30 at a contact zone 30A (FIG. 3a). The disconnection blade 31 is advantageously mounted under stress in such a way that during its opening, it departs sufficiently from the electrode 21 so as no longer to constitute an obstacle against the movement of the insulating flap 41.

The force responsible for the movement of the insulating flap 41 can be of any kind, but will preferably be an elastic restoring force. To this end, the arc breaking means 40 advantageously comprise an elastic means 70, of the spring type, mounted so as to exert an elastic restoring force on the insulating flap 41, said restoring force being exerted in a direction substantially parallel to the compression axis of the elastic means 70.

In a particularly advantageous manner, the arc breaking means 40 and the disconnection means 30 are arranged relatively such that when the disconnection means 30 is in its closed position (FIG. 3a) the arc breaking means 40 are constrained elastically, for example by means of the elastic means 70, and come to bear against the disconnection means 30 at the level of the support zone 30A.

According to another particularly advantageous characteristic of the invention, the device comprises means 50 for indicating the state of the varistor 10, said indication means 50 being actuated by the arc cutting means 40. Thus, during of the opening of the disconnection means 30, the release and the displacement of the arc breaking means 40 will trigger a change of state of the indication means 50 which will then take a configuration likely to inform third parties that a varistor is disconnected.

The indication means 50 can obviously be visual, or even auditory indication means. According to a preferred variant illustrated in FIGS. 3a and 3b, the indication means 50 are formed by a display member 51, preferably mounted on the means of arc cut 40 and capable of moving with the latter opposite a window 61 formed in the housing 60 of the device.

Preferably, the display member 51 can be formed by a colored panel, welded, glued on or made in one piece with the insulating flap 41. The maximum stroke of the insulating flap 41 is preferably predetermined so that the display member 51 comes to be positioned substantially opposite the window 61 when the insulating flap 41 reaches its terminal position.

In a particularly advantageous manner, the display member 51 may be colored in red, so that the visual appearance through the window 61 has, when the varistor 10 is connected, a red coloration informing third parties of the need to replace the protective component, namely varistor 10.

Obviously, the indication means 50 can also be formed by remote signaling means. According to this variant, the device will be designed in such a way that the movement of the insulating flap 41 has the effect of actuating a mechanism capable of triggering a remote signaling system for the state of the varistor.

Several embodiments of the invention will now be described with reference to Figures 1 to 4b.

According to a first embodiment of the invention illustrated in FIG. 1, the arc cutting means 40 are preferably formed by a substantially flat plate, forming the insulating flap 41, and the lateral parts 43 of which extend, from the central part 42, over a sufficient distance on either side of the disconnection means 30 and / or the means connection 20 to prevent the arc cutting means 40 from being bypassed by the electric arc.

In particular, the lateral parts 43 extend on either side of the central part 42 so as to prevent the latter from being circumvented by the electric arc. The structure and shape of the insulating flap 41 thus makes it possible to increase the distance that the electric arc must travel to electrically connect the disconnection blade 31 to the electrode 21, which amounts to increasing the insulation distance between the means disconnection 30 and the connection means 20.

Within the meaning of the invention, the isolation distance is defined as the distance that the electric arc must travel in the insulating medium, for example air, to electrically connect the connection means 20, in particular the electrode 21 , by means of disconnection 30.

A person skilled in the art will thus be able to produce an insulating flap 41 the lateral parts of which extend over a distance such that it makes it possible to significantly increase the isolation distance between the disconnection means 30 and the connection means. 20, in comparison with the devices of the prior art not comprising such an insulating flap. For purely indicative purposes, the insulating flap 41, specifically the lateral parts 43 of the latter can be dimensioned so as to multiply at least by two, preferably by three, the isolation distance between the disconnection means 30 and the connection means. 20.

By way of illustration, the shortest path T1 which the electric arc could take in the absence of the insulating flap 41 is shown in dotted lines in FIG. 1. The path T2 which the electric arc could take also has been shown. presence of the insulating flap 41 provided with the only central part 42 and finally the path T3 of greater length than the paths T1 or T2, which the electric arc must take when the insulating flap 41 provided with its central part 42 and the lateral parts 43 is in the interstitial space 11.

The length of the path T3 thus corresponds to the isolation distance between the disconnection means 30 and the connection means 20, which is significantly increased due to the presence of the lateral parts 43.

According to another embodiment of the invention, the arc cutting means 40 advantageously form an envelope, shaped so as to come at least partially surround the disconnection means 30 and / or the connection means 20 when the means of disconnection 30 is in the open position.

According to a first variant not shown, the envelope may include a substantially planar central portion intended to be interposed between the disconnection blade 31 and the electrode 21, and substantially curved side portions so as to coat at least partially either the electrode 21, or the disconnection blade 31 so as to increase the isolation distance between them.

According to another alternative embodiment illustrated in FIGS. 2 to 4b, the arc cutting means 40 may comprise a sleeve 44, forming the envelope and intended to come to surround, at least partially, either the disconnection blade 31, or the corresponding electrode 21.

Preferably, the sleeve 44 has a U-shaped cross section, as illustrated in Figures 2, 3a and 3b. Advantageously, the sleeve 44 is delimited laterally by three walls 44A, 44C and 44D and longitudinally by a bottom 44B. All of these walls thus delimits an interior housing 45 opening at an opening 46 allowing the sleeve 44 to come to be fitted around the connection blade 21, thus coating the latter (FIG. 3b).

According to a first variant of the invention illustrated in Figures 2, 3a and 3b, the arc breaking means 40 are mounted movable in rotation.

The sleeve 44 is then advantageously secured to an articulated arm 49, preferably formed by a plate. Preferably, the sleeve 44 is integrally formed with the arm 49, then forming with the latter a single and same functional part.

The sleeve 44 advantageously projects from the plate formed by the arm 49. Thus, the walls 44A and 44C of the sleeve 44 extend substantially perpendicularly to the arm 49, thus forming the internal housing 45 which opens on the side of side 10A of varistor 10.

The arm 49 is advantageously mounted mobile in rotation about an axis 100, so that it can pivot around this axis under the action of the restoring force exerted by the elastic means 70. The arm 49 then simultaneously drives the insulating flap 41 in a rotational movement.

In a particularly advantageous manner, and as shown in FIGS. 3a and 3b, the elastic means 70 preferably extends between a first fixed end 71, for example secured to the housing 60, and a second end 72, fixed on or coming to bear against the arm 49 and capable of moving with the latter within the housing 60. Once the insulating flap 41 released from the disconnection blade 31, the elastic means 70, of the spring type, exerts on the arm 49 a driving force, causing the latter in a rotational movement around the fixed axis 100.

During the movement of the insulating flap 41 from its initial position illustrated in FIG. 3a to its final position illustrated in FIG. 3b, the arm 49 advantageously moves in a direction substantially parallel to the face 10A of the varistor 10 and this until that the bottom 44B of the sleeve 44 abuts against the electrode 21, the latter then being isolated within the interior housing 45 of the sleeve 44. This abutment then constitutes a means making it possible to determine with certainty the terminal position of the insulating flap 41, which makes it possible to adjust the relative positioning of the window 61 and of the display member 51. Obviously, one could consider using other abutment means to perform this tracking function , in particular stop pads (not shown) fixed for example on one of the faces of the housing 60 and arranged so as to interrupt the movement of the arm 49.

In a particularly advantageous manner, the sleeve 44 has an extension 47, substantially perpendicular to the face 44C of said sleeve. The extension 47 advantageously forms one of the side walls 43 of the insulating flap 41 and is interposed between the disconnection blade 31 on the one hand, and one of the faces 10A of the varistor 10 on the other hand, so as to prevent bypassing by an electric arc of the central part 42 of the insulating flap 41 formed by one of the faces 44C of the sleeve 44.

In this alternative embodiment, the opposite faces 44A, 44C of the sleeve 44 can advantageously be curved, so as to adapt to the rotational movement of the insulating flap 41. This makes it possible in particular to adjust the dimensions of the interior housing more precisely. 45 to the dimensions of the electrode 21. According to another alternative embodiment of the invention illustrated in FIGS. 4a and 4b, the arc breaking means 40 are mounted movable in translation. According to this variant, an elastic means of the spring type (not shown) tends to resiliently return the insulating flap 41 to a position illustrated in FIG. 4b in which the sleeve 44 at least partially envelops the electrode 21.

According to this variant, the displacement of the sleeve 44 takes place in a direction D substantially rectilinear and parallel to the plane of extension of the face 10A of the varistor 10.

In the same way as in the variant described above, the sleeve 44 is advantageously provided with an interior housing 45 within which the electrode 21 is housed.

According to this variant, the device preferably comprises guide means (not shown) for guiding in translation of the insulating flap 41 between its initial position, in which it is constrained between the spring on the one hand and the blade of disconnection 31 on the other hand, and a terminal position in which it is released from the disconnection blade 31 and isolates the latter from the electrode 21.

The operation of the overvoltage protection device according to the invention will now be described on the basis of the preferred variant embodiment illustrated in FIGS. 3a and 3b.

When an excessive current or a prolonged use causes the rupture or the fusion of the thermal welding ensuring the connection by contact between the disconnection blade 31 on the one hand and the electrode 21 of the varistor 10 on the other hand, the blade disconnection 31 deviates, by spring effect, from the electrode 21 thus creating an interstitial space between the electrode 21 of a part and the disconnection blade 31 on the other hand. By moving away, the disconnection blade 31 thus releases the insulating flap 41 which, under the action of the restoring force exerted by the elastic means 70 on the arm 49, pivots around the axis 100 and comes to be positioned, at least partially, in the interstitial space 11 between the electrode 21 and the disconnection blade 31. In particular, the central part 42 of the insulating flap 41, formed by one of the faces 44C of the sleeve 44, is interposed between the disconnection blade 31 and the electrode 21. The other faces 44A, 44D of the sleeve 44 then envelop the electrode 21, thus increasing the isolation distance between the latter and the disconnection blade 31.

Obviously, the arc cutting means 40, and in particular the insulating flap 41 could, without departing from the scope of the invention, be formed by a sleeve mounted movable in translation or in rotation and designed so as to isolate not the electrode 21, but the end 31 A of the disconnection blade 31 intended to be welded to the electrode 21.

The protection device according to the invention therefore makes it possible, thanks to a particularly simple and reliable assembly, to ensure rapid and systematic disconnection of the protection component in the event of the latter heating up.

Another advantage of the protection device according to the invention is that it makes it possible to avoid having to use an independent and complementary breaking device, of the fuse or circuit breaker type. In applications where the use of an additional cut-off device proves essential, it is possible to increase the size of the latter in complete safety.

Another advantage of the protection device according to the invention is that its resistance to overvoltages is improved. POSSIBILITY OF INDUSTRIAL APPLICATION

The invention finds its industrial application in electrical devices for protection against transient overvoltages.

Claims

- Device for protecting an electrical installation against overvoltage comprising: - at least one protection component (10), provided with connection means (20) to the electrical installation, - a disconnection means (30) for the component protection (10) relative to the electrical installation, adapted to ensure the disconnection of the latter at the connection means (20), and capable of moving from a closed position to an open position in thus creating an interstitial space (11) between the disconnection means (30) and the connection means (20), characterized in that it comprises arc breaking means (40), intended to prevent the formation of electric arcs between the disconnection means (30) and the connection means (20) when the disconnection means (30) is in the open position, said arc breaking means (40) being formed by an insulating flap ( 41), able to move at least part ily within the interstitial space (11) and comprising a central part (42), intended to be interposed between the disconnection means (30) and the connection means (20) and side parts (43), shaped so as to prevent the arc breaking means (40) from being bypassed by the electric arc.

- Device according to claim 1 characterized in that the arc breaking means (40) are formed by a substantially planar plate, the lateral parts (43) of which extend from the central part (42) over a sufficient distance on either side of the disconnection means (30) and / or connection means (20) to prevent the arc breaking means (40) from being circumvented by the electric arc.

- Device according to claim 1 characterized in that the arc cutting means (40) form an envelope, shaped so as to come surround, at least partially, the disconnection means (30) and / or the connection means ( 20) when the disconnection means (30) is in the open position.

- Device according to claim 3 characterized in that the arc cutting means (40) comprise a sleeve (44) having a U-shaped cross section.

- Device according to one of claims 1 to 4 characterized in that the arc breaking means (40) and the disconnection means (30) are mounted relatively in such a way that when the disconnection means are opened, the latter frees the arc breaking means (40), thus authorizing the displacement of the latter.

- Device according to one of claims 1 to 5 characterized in that the arc cutting means (40) and the disconnection means (30) are arranged so that when the disconnection means is in its closed position , the arc breaking means (40) are elastically forced and bear against the disconnection means (30).

- Device according to one of claims 1 to 6 characterized in that the arc cutting means (40) comprise an elastic means (70), mounted so as to exert an elastic restoring force on the insulating flap (41) , said restoring force being responsible for the movement of the latter. - Device according to one of claims 1 to 7 characterized in that the arc cutting means (40) are mounted movable in rotation.

- Device according to one of claims 1 to 7 characterized in that the arc cutting means (40) are mounted movable in translation. -A device according to one of claims 1 to 9 characterized in that it includes means for indicating (50) the state of the protective component, said means for indicating (50) being actuated by the cutting means arch (40). -A device according to one of claims 1 to 10 characterized in that the indication means (50) are formed by a display member (51), mounted on the arc cutting means (40) and capable of being move opposite a window (61) formed in the housing (60) of the device.