EP1815569A1

EP1815569A1 - Improved disconnection overvoltage-protection device

Info

Publication number: EP1815569A1
Application number: EP05812264A
Authority: EP
Inventors: Michel Jean Georges Donati; Alain René Robert LAGNOUX
Original assignee: ABB France SAS
Current assignee: ABB France SAS
Priority date: 2004-10-25
Filing date: 2005-10-25
Publication date: 2007-08-08
Anticipated expiration: 2025-10-25
Also published as: FR2877156A1; CN101048923A; WO2006045946A1; EP1815569B1; ES2383046T3; ATE550815T1; CN101048923B

Abstract

The invention relates to a device protecting an electrical installation against overvoltages, comprising at least one protection component (10) provided with means for connection (20) to an electrical installation; a means (30) for disconnection (30) of the protection component (10) from the electrical installation, said means being adapted in such a way as to ensure disconnection of said component at connection means (30) level and being able to move from a closed position to an open position creating an interstitial space (11) between the disconnection means (30) and the connection means (20), characterized in that it comprises anti-reverse means (50) which are adapted in such a way as to prevent the disconnection means (30) from returning towards the closed position thereof when it moves away from the connection means (20) by an insulation distance which is above a pre-determined threshold distance (d). Devices offering protection against transitory overvoltages..

Description

OVERVOLTAGE PROTECTION DEVICE HAVING IMPROVED DISCONNECTION CAPABILITY

TECHNICAL AREA

The present invention relates to the general technical field of protective devices for installations and electrical equipment against transient electrical surges, especially due to lightning.

The present invention relates more particularly to a device for protecting an electrical installation against surges comprising:

at least one protection component provided with connection means to the electrical installation,

a means for disconnecting the protection component with respect 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 a position of opening thereby creating an interstitial space between the disconnecting means and the connection means.

PRIOR ART

Protection devices for electrical installations are now commonly used to protect electrical or electronic devices against overvoltages that may for example be generated by discharges due to lightning.

These protection devices generally comprise one or more overvoltage protection components, such as by example a varistor or a spark gap. When the component or components are exposed to voltages higher than a predetermined threshold value, they are likely to discharge the fault current to earth, while limiting the overvoltage to a value compatible with the behavior of the installation and the equipment. connected to it. At the end of their life, the protection components are likely to present significant heating (usually greater than 15O ⁰ C) that can lead to serious damage to the installation, or even risks for the user (fire for example). This is the reason why overvoltage protection devices are generally provided with thermal disconnection means. These thermal disconnection means are intended to isolate the protective component of the electrical installation to be protected in the event of excessive heating of the latter exceeding a predetermined value in order to limit the risk of fire.

The thermal disconnection means may thus be formed by a metal disconnection blade, welded to one of the electrodes of the protection component using for example a thermal weld. The disconnection blade is generally subjected to a mechanical stress tending to move it away from the corresponding electrode so that when excessive overvoltage or prolonged use causes the solder to break or melt, the disconnection blade away from the electrode, thus isolating the protective component of the installation to be protected.

Although they are commonly used, such devices nevertheless suffer from significant disadvantages.

Thus, after melting or breaking of the weld, the isolation distance created between the disconnection blade and the electrode of the protection component is generally quite small. Therefore, if the disconnection takes place under Unfavorable voltage and current conditions, it may happen that the mechanical opening of the disconnection means is not sufficient to completely isolate the varistor of the electrical installation, the electric arc created during the opening of the disconnection blade being able to hold between the disconnection blade and the corresponding electrode. It may also happen, in some cases, that an electric arc is reformed between the electrode of the protection component and the disconnection blade a few moments after opening of the latter.

This phenomenon has the effect of delaying the effective disconnection of the protection component, and significantly limiting the breaking capacity of the device.

To overcome this drawback, it is known to use a complementary cut-off device, of the circuit-breaker or fuse type, which ensures the permanent interruption of the current flowing in the protection device.

However, the size of the complementary cut-off device must preferably be adapted to the capacity of the protection component, which generates technical constraints and increases the costs of implementing the overall protection equipment. In addition, the complementary cut-off device generally ensures the simultaneous and indiscriminate isolation of all the protective components of the device, while it is desirable instead to isolate only the protective component or components with excessive heating and to keep the other protection components in service.

SUMMARY OF THE INVENTION

The objects assigned to the invention therefore aim to remedy the various disadvantages listed above and to propose a new solution. protection device of an electrical installation against overvoltages which, while being of simple design, has an improved disconnection capacity compared to known devices.

Another object of the invention is to provide a new device for protecting electrical installations against overvoltages to ensure 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 particularly robust and resistant.

Another object of the invention is to provide 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 surge protection device for accelerating the effective breaking of the current during the disconnection.

The objects assigned to the invention are achieved by means of a device for protecting an electrical installation against surges comprising: at least one protection component, provided with means of connection to the electrical installation,

a means for disconnecting the protection component with respect 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 a closed position; opening position by creating an interstitial space between the disconnecting means and the connecting means, characterized in that it comprises anti-recoil means adapted to prevent the disconnection means from returning to its closed position when the latter separates the connection means from an isolation distance greater than a predetermined threshold distance.

SUMMARY DESCRIPTION OF THE INVENTION

Other features and advantages of the invention will appear in more detail on reading the description which follows, and with the aid of the accompanying drawings given purely by way of illustration and not limitation, among which:

- Figure 1 illustrates, in a front view, an overvoltage protection device according to the invention in its disconnected position.

- Figure 2 illustrates, in a detailed front view, the right half of the protective device according to the invention in its service position.

- Figure 3 illustrates, in a detailed front view, the right half of the protective device according to the invention in an intermediate position between the service position and the disconnected position.

- Figure 4 illustrates, in a detailed front view, the right half of the protective device according to the invention in its disconnected position.

BEST MODE OF REALIZING THE INVENTION

The protection device 1 against overvoltages according to the invention is intended to be connected bypass (or in parallel) on the equipment or the electrical installation to be protected. The term "electrical installation" refers to any type of device or network powered electrically and likely to experience voltage disturbances, including transient overvoltages due to lightning.

The overvoltage protection device 1 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 bypass between a phase and the earth, is connected between the neutral and the earth, between the phase and the neutral or between two phases (case of differential protection).

The protection device 1 according to the invention comprises at least one protection component 10 intended to protect the electrical installation against overvoltages. In the remainder of the description, it is considered that each overvoltage protection component is formed by a varistor, it being understood that the use of a varistor is only indicated by way of example and does not constitute any a limitation of the invention.

The protection device 1 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 disposed within an electrically insulating housing 60, and may be in the form of a cartridge adapted to be electrically connected to a fixed base (not shown) with the aid of at least first and second connection pads 22, 23. One of the poles of the varistor 10 is thus connected directly to the first connection pad 22, the other pole of the varistor 10 being connected to the connection means 20. The latter are preferably formed by an electrode 21, for example in the form of a metal blade. The electrode 21 advantageously projects, for example at 90 degrees, from one of the faces 10A of the varistor 10.

According to the invention, the protection device 1 also comprises a disconnection means 30 capable of disconnecting the varistor 10 from the electrical installation, particularly in the event of failure of the latter. The disconnecting means 30 is specifically shaped and adapted to ensure the disconnection of the varistor 10 at the connection means 20 and is for this purpose capable of moving from a closed position, illustrated for example in Figure 2 towards an open position illustrated in FIG. 4, thus creating an interstitial space 11 between the disconnection means 30 and the connection means 20.

Preferably, the disconnection means 30 is prestressed, that is to say that it is mounted in stress, in its closed position, and subjected to an elastic restoring force tending to propel it towards its position. opening. This elastic restoring force may be external, especially if the disconnecting means 30 is compressed by a spring, or internal, in the case of an elastic disconnection means.

Even more preferably, the disconnection means 30 is formed by an electrically conductive elastic disconnecting disc 31 (for example made of metal) which, in the closed position, is prestressed, that is to say advantageously welded in stress on the connection means 20, specifically on the electrode 21, preferably using a heat-fusible seal (not shown).

The term "elastic" refers to the fact that the disconnection blade 31 has an intrinsic elasticity giving it a sufficient character flexible and flexible to allow its connection and its contact under stress with the electrode 21 of the varistor 10. The elastic disconnection blade 31 thus advantageously extends between a free end 31A adapted to come, in the closed position, in electrical contact with the electrode 21 via the thermal weld, and a fixed end 31 B in permanent electrical contact with the second connection pad 23. In this closed position, the varistor 10 is in use, c ' that is, it is electrically connected to the electrical installation so as to protect it against voltage disturbances.

In its closed position, the elastic disconnection blade 31 is subjected to its own elastic return force which tends to move it away from the connection means, at least at its free end 31A. The elastic disconnection blade 31 is therefore advantageously elastically constrained between its closed position and its open position so that during the fusion (or rupture) of the weld, the resilient disconnection blade 31, and in particular the The free end 31 A of the latter is propelled and moves away, under the action of the intrinsic elastic restoring force, from the electrode 21.

Upon opening, an electric arc 40 (illustrated in FIG. 3) may be formed in the interstitial space 11 between the disconnection means 30 and the connection means 20. This electric arc 40 continues to flow current, thus delaying the effective disconnection of the protection component 10.

The formation of the electric arc 40 between the connection means 20 and the disconnection means 30 requires a certain amount of energy, all the more important since the isolation distance between the connection means 20 and the disconnection means 30 is high. . The term "isolation distance" refers to the average thickness of the air gap separating the connecting means 20 from the disconnecting means 30 when the latter moves away from the connection means 20 towards its open position. . It is thus possible to define an optimum isolation distance for which the probability of starting an electric arc 40 between the connection means 20 and the disconnection means 30 is sufficiently small to be considered as negligible in the conditions of connection. The use of the protection device 1. In the remainder of the description, the optimal isolation distance is often referred to as "predetermined threshold distance", the latter being able to be obtained by simple routine tests.

Despite the prior determination of the optimum isolation distance between the connection means 20 and the disconnection means 30, it happens that the disconnection means 30 does not go directly from its closed position to a corresponding permanent open position. at a steady state of equilibrium. Thus, the disconnecting means 30 most often passes through a transient and unstable state where it oscillates around its open position, making several trips between its closed position and its open position.

The frequency and the intensity of this phenomenon are all the more important if the disconnecting means 30 is prestressed and / or formed by an elastic disconnection plate 31 prestressed. Indeed, under the action of its intrinsic elastic return force, the resilient disconnection blade 31 is propelled to its open position and driven in an oscillatory movement damped due to its momentum. This phenomenon can adversely affect the efficiency of the disconnection, the elastic disconnection blade 31, in particular the free end 31A of the latter, coming closer, in the extreme positions of this oscillatory movement, to the electrode 21. then observes a degradation of the isolation distance and an increase in the time required to isolate the faulty protection component of the electrical installation.

To overcome this drawback, and according to an essential characteristic of the invention, the protection device 1 according to the invention is provided with anti-recoil means 50, adapted to prevent the disconnection means 30, and in particular the elastic disconnection blade 31, to return to its closed position when it deviates from the connection means 20 by an isolation distance greater than the predetermined threshold distance d.

The anti-recoil means 50 thus make it possible to prevent the disconnection means 30, and in particular the elastic disconnection blade 31, from going back when the optimum isolation distance is reached. The anti-recoil means 50 also make it possible to limit the phenomenon of oscillation of the elastic disconnection blade 31.

Advantageously, the anti-recoil means 50 are shaped and arranged to abut against the disconnection means 30 when the isolation distance is greater than the predetermined threshold distance d, thus forming a stop against the displacement of the disconnection means 30. from its open position to its closed position.

According to a preferred embodiment of the invention illustrated in Figures 1 to 4, the anti-recoil means 50 comprise a movable member 51 adapted to move under the control of the opening movement of the disconnection means 30. In particular, the movable element 51 is preferably designed to come, in its operative position, in active support against the disconnection means 30 when the predetermined threshold distance d is reached (Figure 1). As shown in FIGS. 1 and 4, the movable element 51 comes, in its operative position, to be positioned at least partly in the path of the disconnection means 30, thus forming an obstacle against the latter and preventing the disconnecting means 30 to go back to the connection means 20, in particular to the electrode 21, once the predetermined threshold distance has been reached.

Preferably, and as illustrated in FIGS. 2 to 4, the movable element 51 is preferably formed by a finger 52, preferably fixed on or integrally formed with a support 53 secured for example with the housing 60. The movable element 51 is advantageously capable of moving relative to the support 53, for example at a hinge 58, and this against or under the action of an elastic restoring force F tending to bring it back to its functional position (shown in Figure 4) or rest (shown in Figure 2). This elastic restoring force F can be exerted via resilient means (not shown) of the spring type, interposed between the support 53 and the finger 52. According to the preferred embodiment of the invention illustrated in FIGS. movable element 51, and in particular the finger 52, has an intrinsic elasticity conferring its properties of flexibility and flexibility relative to the support 53.

Advantageously, the movable element 51 has a substantially elongate shape and comprises a guide ramp 54 (FIG. 3) disposed relative to the disconnecting means 30 such that when it is opened, the disconnecting means 30 comes into active contact against the guide rail 54 and slides along the latter through its free end 31 A.

The expression "active support" refers to the fact that the means of disconnection 30, and in particular the free end 31A of the blade of elastic disconnection 31 comes to exert pressure on the movable member 51 tending to push the latter against the elastic restoring force F. As an illustration, when the protective device 1 according to the invention is in the vertical position shown on Figures 1 to 4, the disconnection means 30 abuts against the finger 52 so as to lift it. The finger 52 is then pushed under elastic stress towards the support 53.

When the finger 52 is in its rest position shown in Figure 2, the guide ramp 54 is preferably inclined, so as to facilitate its engagement by the disconnection means 30, during the opening of the latter.

Preferably, the movable element 51 extends between two ends 51A, 51B, namely a first end 51A, integral with the support 53, and a second free end 51B and separated from the first end 51A at least by the guide ramp 54 (Figure 3).

Advantageously, one of the ends 51 A, 51 B of the movable member 51, and preferably the second free end 51 B, forms a stop means 55 against the disconnection means 30 when the predetermined threshold distance d is reached or exceeded, and when the disconnecting means 30 is close to its open position (Figure 4). The guide ramp 54 thus ends advantageously by the stop means 55, and its length substantially corresponds, on average, to the predetermined threshold distance d.

Thus, when the disconnection means 30 reaches the end of travel on the guide ramp 54, reaching or slightly exceeding the stop means 55, the movable element 51, released from the disconnection means 30, returns, under the effect of the elastic restoring force F towards its rest position and is positioned in the return path of the disconnecting means 30, forming thus an obstacle to meet the latter. As illustrated in Figure 4, the movable member 51 and the disconnecting means 30 can thus bear against each other in a stable equilibrium position.

The anti-recoil means 50 described above, if they make it possible to guarantee the respect of a minimum isolation distance between the connection means 20 and the disconnection means 30, and to avoid falling below this distance d However, it is not possible to completely eliminate the oscillations of the disconnection means 30, in particular at the free end 31A of the resilient disconnection blade 31.

To overcome this drawback, the protection device 1 according to the invention advantageously comprises an additional locking means 56 adapted to cooperate with the anti-recoil means 50 so as to immobilize the disconnection means 30 in its open position, as shown in Figures 1 and 4.

In particular, the anti-recoil means 50 and the blocking means 56 are mounted so as to cooperate together to prevent oscillations of the free end 31A of the resilient disconnection blade 31 when the predetermined threshold distance d is reached.

The anti-recoil means 50 and the blocking means 56 thus form, in combination, anti-oscillation means.

Thus, the elastic disconnection blade 31 is subjected, in its closed position, to an intrinsic elastic return force F '(FIG. 3) tending to return it to its open position illustrated in FIG. recess 50 are then designed to oppose the movement of the elastic disconnection blade 31 in a direction F "(Figure 4) substantially opposed to the intrinsic elastic return force F ', when the predetermined threshold distance d is reached.

The blocking means 56 is preferably located after the anti-recoil means 50 in consideration of the direction of travel "go" S of the disconnection means 30, that is to say the direction corresponding to its passage from the closing position to the open position (Figure 3).

The blocking means 56 is further advantageously arranged at a sufficiently small distance from the anti-recoil means 50 to limit the amplitude of the oscillations of the disconnection means 30 around its open position, thereby ensuring the rapid immobilization of the latter .

In this way, the disconnection means 30 is maintained, in its open position, between the anti-recoil means 50 and the blocking means 56. More specifically, the blocking means 56 and the stop means 55 come from preferably simultaneously bearing against the free end 31 A of the resilient disconnection blade 31 and more precisely on either side of the latter.

Preferably, the locking means 56 is formed by a pin 57 secured to or integral with the support 53 and protruding from the support 53 so as to form a stop against the disconnecting means 30 when the opening of the latter.

Advantageously, the anti-recoil means 50 and the blocking means 56 are preferably formed from a non-electrically conductive material, such as polyamide, or any other insulating plastic material having equivalent elastic properties. The operation of the protection device according to the invention will now be described with reference to FIGS. 1 to 4.

When an overvoltage of sufficient amplitude occurs, the protective device 1, mounted in parallel with the electrical installation, becomes conductive and flows to the ground the lightning current. When excessive current or prolonged use causes the breaking or fusion of the thermal weld providing the contact connection between the elastic disconnection blade 31 and the electrode 21 of the protection component 10, the elastic disconnection blade 31 is separates, by spring effect, the electrode 21, thus creating an interstitial space 11 between these contacts.

By moving aside, the elastic disconnection blade 31 engages and bears against the guide ramp 54 of the anti-recoil means 50, thus pushing the latter against the elastic return force F tending to bring them back to their position. rest. The anti-recoil means 50 then fade, under the control of the movement of the disconnecting means 30, thus allowing the free movement of the latter. The disconnection means 30 then bears against the blocking means 56 and simultaneously reaches the end of the stroke on the guide ramp 54, reaching or exceeding the stop means 55.

This has the effect of releasing the movable member 51 which returns, at least partially, to its rest position by blocking the elastic disconnection blade 31 in its open position, the stop means 55 then bearing against the free end 31 A of the resilient disconnection blade 31.

The free end 31A of the elastic disconnection blade 31 is then trapped in the space between the anti-recoil means 55 on the one hand and the blocking means 56 on the other hand, this space being sufficiently reduced. to dampen almost instantaneously the oscillations of the free end 31 A of the resilient disconnection blade 31.

The disconnecting means 30 is then immobilized in its open position, at an optimum and sufficient isolation distance of the connection means 20 to limit the risk of an electric arc 40 starting between these two metal parts.

The protection device 1 according to the invention therefore allows optimum control of the disconnection, thus providing greater operational safety to users than known devices.

Another advantage of the device according to the invention is that it makes it possible to guarantee, despite its particularly simple design, effective isolation of the defective or degraded protection component vis-à-vis the electrical installation.

POSSIBILITY OF INDUSTRIAL APPLICATION

The invention finds its industrial application in the manufacture of devices for protection against overvoltages.

Claims

- Device for protecting an electrical installation against surges comprising:

at least one protection component (10) provided with connection means (20) for the electrical installation,

- Disconnection means (30) of the protection component (10) relative to the electrical installation, adapted to disconnect the latter at the connection means (20), and capable of moving from a closing position to an open position by creating an interstitial space (11) between the disconnecting means (30) and the connection means (20), characterized in that it comprises anti-recoil means (50) adapted to prevent the disconnecting means (30) from returning to its closed position when the latter deviates from the connection means (20) by an isolation distance greater than a predetermined threshold distance (d).

- Device according to claim 1 characterized in that the anti¬ recoil means (50) are shaped and arranged to bear against the disconnecting means (30) when the isolation distance is greater than the predetermined threshold distance (d) , thus forming a stop against the displacement of the disconnection means (30) from its open position to its closed position.

- Device according to claim 1 or 2 characterized in that it comprises an additional locking means (56) adapted to cooperate with the anti-recoil means (50) so as to immobilize the disconnection means (30) in its position d 'opening. 4 - Device according to claim 3 characterized in that the locking means (56) is located after the anti-recoil means (50) in consideration of the direction of movement (S) of the disconnecting means (30) and arranged at a distance sufficiently low anti-recoil means (50) for limiting the amplitude of oscillations of the disconnection means (30) around its open position.

5 - Device according to claim 4 characterized in that in the open position, the disconnecting means (30) is maintained between the anti-recoil means (50) and the locking means. (56).

6 - Device according to any one of the preceding claims characterized in that the anti-recoil means (50) comprise a movable member (51) adapted to move under the control of the opening movement of the disconnecting means (30), said movable member (51) being adapted to come into operative position in active support against the disconnecting means (30) when the predetermined threshold distance (d) is reached.

7 - Device according to claim 6 characterized in that in its operative position, the movable member (51) is positioned, at least in part, in the path of the disconnecting means (30) thereby forming an obstacle to meet this latest.

8 - Device according to claim 6 or 7 characterized in that the movable member (51) is subjected to an elastic restoring force (F) tending to bring it back to its operative position.

9 - Device according to one of claims 6 to 8 characterized in that the movable element (51) comprises a guide ramp (54), arranged such that the disconnecting means (30) comes into active support against and along the latter during its opening.

10 -Dispositif according to claim 9 characterized in that the length of the guide ramp (54) substantially corresponds to the predetermined threshold distance (d).

11 -Dispositif according to one of claims 6 to 10 characterized in that one end (51A, 51 B) of the movable member (51) forms a stop means (55) against the disconnecting means (30) in its open position.

12 - Device according to any one of the preceding claims characterized in that the disconnecting means (30) is prestressed.

13 - Device according to claim 12 characterized in that the disconnecting means (30) is formed by an elastic disconnection blade (31) subjected, in its closed position, to an intrinsic elastic return force (F ') tending to bring it back to its open position, and in that the anti-recoil means (50) are designed to oppose the movement of the elastic disconnection blade (31) in a direction (F ") substantially opposite to the force intrinsic elastic return member (F ') when the predetermined threshold distance (d) is reached.

14 - Device according to claims 3 and 13 characterized in that the elastic disconnection blade (31) extends between a fixed end (31B) and a free end (31A), and in that the anti-recoil means (50) ) and the locking means (56) are mounted to cooperate together to prevent oscillations of said free end (31A) when the predetermined threshold distance (d) is reached.