EP0793317A1 - Overvoltage arrester device - Google Patents

Abstract

The electrodes (1,2) are flat plates substantially parallel to each other at the ends of power conductors (5). The free ends of the plates carry points between which an arc is struck by overvoltage. The upper electrode (1) is pivotable about an axis (3) to vary the distance between the points. The flows of current (6) in the two electrodes are 180 degrees out of phase and in opposite directions so that their magnetic fields produce mutual repulsion which drives the electrodes apart. After arc extinction the movable electrode is restored to its original position by a spring (19).

Description

The invention relates to an overvoltage protection device with a first electrode and a second electrode spaced apart from the first electrode.

Surge protection devices are known in the prior art which consist of a spark gap. This can be designed both as an air spark gap and as a gas discharge spark gap. If an overvoltage is discharged via such a spark gap, the overvoltage in the network is reduced very sharply to the value mentioned for the residual voltage. However, the spark gap is not able to transmit the current driven by the normal mains voltage via the spark gap, i.e. to extinguish the arc in the spark gap. This so-called follow-up current is usually extinguished either by means of a fuse connected upstream in the system, as a result of which the power supply is interrupted, or with the aid of a varistor arranged in series with the spark gap, as a result of which the effectiveness, that is to say the reduction in the overvoltage, is impaired. The result is a higher residual voltage.

The object of the invention is to provide an overvoltage protection device of the type mentioned at the outset, which has the advantages of a spark gap and reliably extinguishes the arc or follow current.

This is achieved according to the invention in that at least one of the two electrodes is movably mounted at least in sections.

After an arc has been ignited, the distance between such electrodes can be increased by moving the electrodes away from one another with the aid of the forces generated by the arc itself. In this way, an arc that has arisen will be extended relatively quickly until it breaks off, so that the arc is reliably extinguished.

A possible embodiment of the invention can be that the at least one movable electrode is mounted so as to be pivotable about a pivot axis.

A particularly simple realization of the movable bearing is thus achieved.

In this context, however, it can also be provided that at least one movable electrode is mounted so that it can be moved in parallel.

This type of movement is also easy to implement, moreover it is associated with very little friction and is therefore virtually wear-free.

Another feature of the invention can be that the at least one movable electrode is pressed elastically, for example with a spring, in the direction of the other electrode.

This means that after the overvoltage protection device has tripped, that is to say after the arc has extinguished, the movable electrode sections are automatically reset, so that the protection device automatically prepares itself for dissipating a further overvoltage.

In a further embodiment of the invention it can be provided that the electrodes have an approach point and an adjoining spark gap, such as a horn spark gap.

By means of such a spark gap, the arc ignited in the proximity point is quickly withdrawn from the proximity point, so that the thermal stress associated with the arc causes only little or hardly detectable damage.

In this context it can be provided that at the end of the spark gap opposite the approach point at least one electrode element, at least protruding into the space delimited by the electrodes, preferably arranged entirely in this space, such as e.g. Plate, is arranged.

Such electrode elements divide the arc into several partial arcs when the spark gap end is reached, which supports rapid arc extinguishing.

A particularly preferred embodiment of the invention can consist in that the electrodes are arranged enclosing an acute angle, the approach point preferably being arranged in the first edge region of the electrodes and both leads being fixed at a distance from the approach point, preferably at the end of the electrodes opposite the approach point , so that the at least one movable electrode can be moved away from the other electrode by force effects caused by the current flow.

With such an arrangement, the magnetic forces generated by the arc current can be used without any further means for moving the electrodes apart.

It can be particularly advantageous that the electrodes are at least in sections essentially parallel to each other, because this results in a particularly high force effect between the two electrodes.

According to a further embodiment of the invention, it can be provided that at least one electromechanical actuator is connected in series with the electrodes, which moves the movable sections of the electrodes away from one another in the event of an arc being ignited between the electrodes.

A powerful and therefore particularly reliable drive of the at least one movable electrode section can thus be achieved.

In a further development of the invention it can be provided in this connection that the electromechanical actuating element is designed as a coil with an armature connected in series with the electrodes.

This means that a simple magnetic release, which is also common for other applications, can be used.

In a further embodiment of the invention it can be provided that the coil is stationary and the armature is mechanically connected to at least one movable electrode section.

This allows a simple, robust and functionally reliable construction of the electromagnetic actuator.

In this sense, however, it can also be provided that the armature is stationary and the coil is mechanically connected to at least one movable electrode section.

The coil of the actuator has a significantly lower mass compared to the armature, so that such a drive is less sluggish and the arc can therefore be extinguished faster.

It can be advantageous if a spring is arranged between the yoke of the coil and the movable electrode, which presses the movable electrode back into its rest position after the arc is extinguished.

Regardless of the type of drive of the at least one movable electrodes, it can be provided according to a further feature of the invention that a spacer is arranged between the electrodes.

The electrodes are thus kept at a defined distance from one another which always remains the same, so that the tripping voltage of the overvoltage protection device remains essentially constant even after a number of tripping operations.

It may be advantageous for the spacer to be designed as an electrically non-conductive sleeve, so that the gases heated by the arc move the at least one movable electrode away from the other electrode.

As a result, both electrodes can be brought into contact with it.

In a further embodiment of the invention it can be provided that in the space delimited by the electrodes, preferably in the area of the approach point, a preferably plate-shaped element which cuts through the arc can be introduced.

The arc is cut, the current flow is interrupted and the arc is subsequently extinguished.

In this context it can further be provided that the element severing the arc mechanically, e.g. is connected to the at least one movable electrode via a rope, a rod or the like.

The movement of the electrode which is always brought about when an arc is formed can thus be used simultaneously to drive the arc-separating element.

According to another variant of the invention, however, it can also be provided that the element severing the arc can be introduced into the space delimited by the electrodes by means of an electromechanical actuating element through which the arc current flows.

A particularly functionally reliable arc cutting can thus be realized.

Furthermore, it can be provided that the element severing the arc from an electrically non-conductive material, such as e.g. Ceramic, plastic or the like. Is formed.

These materials oppose the arc current with a particularly high resistance, so that a reliable and rapid interruption of the arc is made possible.

According to a further possible embodiment of the invention, it can be provided that the electromechanical actuating element or at least one movable electrode actuates a counter.

By means of such a device, the mechanical state of the electrodes can be determined by the number of overvoltage dissipation processes that have already taken place and conclude that the surge protective device is suitable for use.

In this connection it can be provided that the counter actuates a locking device which holds the electromechanical trigger member or at least one movable electrode section in its open position.

This automatically deactivates the discharge device when it has reached its highest permissible age.

The invention will now be described with reference to the exemplary embodiments shown in the drawings.

• Fig.1a,b eine besonders einfache Ausführungsform der Erfindung in Auf- und Grundriß;
• Fig.1c,d eine Variante der Ausführungsform gemäß Fig.1a,b in Auf- und Grundriß;
• Fig.1e eine Ausführungsform der Erfindung mit parallelverschiebbaren Elektroden im Aufriß;
• Fig.2a,b erfindungsgemäße Überspannungsschutzeinrichtungen mit eine Hörnerfunkenstrecke ausbildenden Elektroden im Aufriß;
• Fig.3a-f Varianten der Erfindung, bei denen der/die beweglichen Elektroden durch elektromechanische Betätigungsglieder angetrieben sind jeweils im Aufriß und
• Fig.4a,b eine Ausführungsform der Erfindung mit einer in die Annäherungsstelle einbringbaren Platte im Aufriß.

It shows:

• 1a, b show a particularly simple embodiment of the invention in elevation and plan;
• Fig.1c, d a variant of the embodiment according to Fig.1a, b in elevation and plan;
• Fig.1e shows an embodiment of the invention with parallel movable electrodes in elevation;
• 2a, b surge protection devices according to the invention with electrodes forming a horn spark gap in elevation;
• 3a-f variants of the invention, in which the movable electrode (s) are driven by electromechanical actuators, each in elevation and
• 4a, b an embodiment of the invention with a plate that can be inserted into the approach point in elevation.

As already mentioned at the beginning, an overvoltage protection device according to the invention dissipates the overvoltage energy with the aid of an arc.

Such an arc has two important properties, among other things: it has a very high temperature, which means that it heats the surrounding atmosphere and thereby builds up local overpressures in the surrounding atmosphere. Furthermore, it allows a relatively large current to flow both in the feed lines and the electrodes and through it itself, which is associated with the formation of magnetic fields and force effects.

The aim of the invention is to extinguish the arc as quickly as possible after the overvoltage has subsided. For this purpose, the invention uses the above-mentioned force effects caused by the arc itself in order to widen the distance between the two electrodes between which the arc burns.

For this purpose, it is provided that at least one of the two electrodes is movably mounted at least in sections. The movable electrode section (s) or the fully movable electrodes are moved away from one another by one or by the interaction of several of the above-mentioned forces.

In principle, the movable mounting can be arbitrary, on the one hand the pivotable mounting of the entire electrode 1 (see FIG. 1a) or the movable electrode section 10 (see FIG. 2 in a manner that allows a parallel displacement of the electrodes 1, 2, as shown for example in Fig.1e.

If the magnetic force effects built up by the arc current are to be used to drive the movable electrode section 10, there are generally two possibilities for this.

The simpler one is shown in FIGS. 1a-e and 2a, b. The electrodes 1, 2 are plate-shaped and arranged to run essentially parallel to one another. At their first ends they are connected to electrical conductors 5, which are used for supplying or discharging current, while at their other ends they form an approach point 4.

The first electrode 1 is movable, namely is mounted so as to be pivotable about a pivot axis 3. If an overvoltage occurs, an arc is formed in the approach point 4 and thereby a current flow symbolized by the arrows 6.

The directions of current flow in the electrodes 1, 2 are 180 ° to one another, that is to say they run in exactly opposite directions. The magnetic fields that form two currents flowing in the opposite direction build up a force that tries to move the two currents away from each other. Due to the pivotable mounting of the first electrode 1, the latter is moved away from the second electrode 2 as a result of the forces mentioned, as a result of which the arc burning in the approach point 4 is extended until it goes out. It is advantageous if a spring 19 is provided, which presses the movable electrode 1 elastically towards the other electrode 2, so that the movable electrode 1 is automatically returned to its rest position immediately after the arc has been extinguished.

Of course it is also possible to move both electrodes 1, 2, e.g. pivotable, when igniting an arc there is a simultaneous movement of both electrodes 1, 2. Furthermore, as shown in FIGS. 1c, d, it is also possible to make one or both electrodes 1, 2 movable only in sections, which to fix the conductor 5 carrying electrode ends rigidly and to provide one or both electrodes 1, 2 with a movable section 10, 20 on which the approach point 4 is arranged.

Another type of movable storage is shown in Fig.1e; here the two electrodes 1, 2 are again plate-shaped, but are mounted such that they can be displaced in parallel by means of rail-like guides 7. If an arc occurs, the two electrodes 1, 2 are separated from each other by the arrows 6 '. Of course, analogously to FIGS. 1a, b, only one of the two electrodes 1, 2 can be mounted so that it can move, while the other is rigid is fixed; Furthermore, an elastic return device for the movable electrodes can be provided.

In all of the embodiments described above, it is in no way imperative to align the two electrodes 1, 2 parallel to one another. For the formation of the magnetic forces driving the movable electrodes 1, 2 or the movable electrode sections 10, 20, it is a prerequisite that the electrodes 1, 2 are arranged enclosing an acute angle to one another and that both supply lines 5 are arranged at a distance from the approach point 4 , so that at least in regions there is an opposite current flow, the magnetic field of which moves the at least one movable electrode 1, 2 away from the other electrode 1, 2.

Apart from this limitation, the two electrodes 1, 2 can have any shape, e.g. the particularly preferred variant according to Fig.2a. The electrodes 1, 2 are provided with supply lines 5 and have sections which run parallel to one another on these supply lines 5 and which sections form the approach point 4.

The approach point 4 continues in a spark gap 8, which is designed according to the drawing in the form of a horn spark gap. One of the electrodes 1 is pivotally mounted about an axis of rotation 3, which is arranged on the end of the electrode 1 opposite the leads 5.

A further development of this embodiment of the invention is shown in FIG. 2b, in which the two electrodes 1, 2 again form a horn spark gap. A plurality of electrode elements 9, which are preferably plate-shaped, are arranged so that they protrude into the space delimited by the horn spark gap. These electrode elements 9 divide the arc into a number of arcs electrically connected in series, as a result of which a quicker quenching takes place. Although not shown separately, according to both embodiments, both electrodes 1, 2 can also be mounted so that they can move in their entirety or only in sections, in both variants a return spring 19 can be provided.

In addition to the magnetic forces of an arc current discussed so far, the gas pressures caused by the arc can also be used to drive the movable electrodes 1, 2. Fig.1e shows a possible variant of the utilization of these gas pressures. Here, the approach point 4 is surrounded by a spacer in the form of a closed sleeve 39, which sleeve 39 is preferably formed from an electrically non-conductive material and which only allows the heated air surrounding the arc to escape in the direction of the two electrodes 1, 2. Since an arc can be relatively hot (approx. 7000-15000K), heating the ambient air also creates sufficiently high pressures to drive the electrodes 1, 2.

Such a sleeve 39 or a gas barrier corresponding to the sleeve 39 can also be provided in all other exemplary embodiments of the invention. Similar to FIG. 3, the forces required to drive the electrodes 1, 2 will be composed of forces caused by the current flow and by gas pressure.

In the case of training forms in which it is provided that the arc moves out of the approach point 4 and runs into a horn spark gap, such as 2a, b-, the sleeve 39 is formed with an opening pointing in the direction of the arc in order not to hinder the arc from running out. The drive effect of the gas pressure on the electrodes 1, 2 is less by this type of design of the sleeve 39, but still sufficient.

Another, albeit more complex, way of utilizing the magnetic forces caused by the arc current is shown in FIGS. 3a-f.

The movable electrodes 1, 2 are moved by one or more electromechanical actuators 30.

The embodiment according to Fig.3a has two terminals 31, 32. Between the terminals 31, 32 there is an electromechanical actuator 30, for example a Magnetic release, and a movable electrode 1 and a fixed electrode 2 connected in series. The stationary electrode 2 can be connected to the clamp 32, for example, via an electrically conductive bracket 36. The movable electrode 1 is fastened on an arm 38 pivotably mounted about a pivot axis 3 and is at a distance L from the fixed electrode 2. The distance L can be set by a non-conductive sleeve 39, which is preferably firmly connected to the fixed electrode 2 and is arranged between the free end 40 of the arm 38 and the fixed electrode 2. The sleeve 39 is arranged so that it surrounds the electrodes 1 and 2. Thus, the gas pressures caused by the arc can also be used to support the electrodes 1, 2 moving apart.

The electromechanical release element 30, in the example shown a conventional magnetic release, has a coil 41 which is connected on the one hand via an electrical line 42 and via the arm 38 to the movable electrode 1 and on the other hand via an electrical line 43 to the connecting terminal 31.

The coil 41 is wound around a sleeve 44, within which an armature 45 is movably received. The sleeve 44 with the coil 41 is fixed in a yoke 46.

The armature 45 is connected to the movable electrode 1 via a tension element 47, which can be, for example, a thin rope or a rod. Although not shown, it could also be provided that the armature 45 is fixed immovably, the coil 41, on the other hand, is movable and is connected to the movable electrode 1, for example via a tension element 47, so that the magnetic forces occurring when an arc current flows, the coil 41 move along the anchor 45.

Between the leg 48 of the yoke 46 facing the movable electrode 1 and the movable electrode 1, a compression spring 19 is arranged which, as shown in the drawing, is supported on the support 50 on the leg 48 of the yoke 46. By means of the compression spring 19, both the movable electrodes 1 and the armature 45 are always moved back into the starting position after the arc which arises when the overvoltage is dissipated has extinguished.

Based on the principle described, it is also possible in this connection to mount both electrodes 1, 2 in a movable manner. 3a shows an example of an extension of the embodiment according to FIG. 3a, in which the second electrode 2 is also arranged on a pivotable arm 38, with a separate actuating element 30 being provided for each of the two arms 38.

As an alternative to pivoting electrodes or electrode sections, it can also be provided in connection with an electromechanical actuating element 30 that one or both electrodes 1, 2 are mounted so as to be displaceable in parallel. Examples of this are shown in FIGS. 3c-f.

According to FIG. 3c, one electrode 2 is immovably fixed and the other electrode 1 is firmly connected to the armature 45 of an electromechanical actuating element 30 via a tension element 47. When an arc occurs, the electrode 1 is moved away from the other electrode 2.

Although two movable electrodes 1, 2 are also provided, only an electromechanical actuator 30 can be used to move them. In the embodiment according to FIG. 3d, the two electrodes 1, 2 are slidably mounted in guides 7 and mechanically connected to the actuating member 30 via a linkage 11. When an arc is formed, the armature 45 of the actuating member 30 is displaced and thereby moves the two electrodes 1, 2 away from one another.

Two pivotably mounted electrodes 1, 2, which form a horn spark gap 8, can be driven by arc current in the manner shown in FIG. 3e.

Similar to FIG. 3 d, the two electrodes 1, 2 are connected to the armature 45 of an actuating element 30 via rods 11.

In this context, it is also possible to increase the distance between electrodes 1, 2 forming a horn spark gap by parallel displacement of one or both electrodes 1, 2. 3f shows an example in which the movable electrode 1 is guided along two rails 7.

Fig. 4a, b shows one possibility of extinguishing an already widened arc particularly quickly.

The basic idea in this embodiment of the invention is to cut the arc-burning path; it is therefore introduced into the space delimited by the electrodes 1, 2, where the arc burns - in the example in FIG. 4, it always remains in the approach point 4 - a plate-shaped element 12.

In principle, this element 12 can now be driven in the manner already described for the movable electrodes 1, 2. If the magnetic force effect between the electrodes 1, 2 is to be used, it is sufficient to connect the element 12 according to FIG. 4 mechanically, for example by means of ropes or rods, to the electrodes 1, 2.

Although not shown, an electromechanical actuator 30 could also be provided for the movement of the element 12.

Electrically non-conductive materials, such as e.g. Ceramics, plastics or the like for use.

Since after repeated triggering of the overvoltage protection device according to the invention, the electrodes 1, 2 can burn off, as a result of which the distance L between the electrodes 1, 2 increases and the trigger voltage increases as a result, which can have a disadvantageous effect on downstream electrical devices, In the embodiment of the invention (not shown), it is provided that a counter is provided.

This counter can be actuated, for example, by a pin 51 which is connected to the armature 45 of an electromechanical actuator 30 (cf. FIGS. 3a, b). In all other embodiments of the invention, in which no electromechanical actuating element 30 is provided, the counter can be actuated by a movable electrode section 10, 20 or by a completely movable electrode 1, 2.

The number unit can be connected to a clearly visible display device which indicates that a predetermined number of triggers has been exceeded. According to another Embodiment of the invention can alternatively or additionally be provided that a locking device is actuated via the counter, which, for example, the armature 45 in its release position after exceeding a certain number of triggers (in the illustrated embodiment in the position in which the movable electrode in the the fixed electrode 2 remote position, in which an ignition of an arc is not possible), whereby the overvoltage protection device is deactivated.

Claims (21)

Surge protection device with a first electrode (1) and a second electrode (2) spaced from the first electrode, characterized in that at least one of the two electrodes (1, 2) is movably mounted at least in sections. Surge protection device according to Claim 1, characterized in that the at least one movable electrode (1, 2) is mounted so as to be pivotable about a pivot axis (3). Surge protection device according to Claim 1, characterized in that at least one movable electrode (1, 2) is mounted so as to be parallel displaceable. Surge protection device according to Claim 1, 2 or 3, characterized in that the at least one movable electrode (1, 2) is pressed elastically, for example with a spring (19), in the direction of the other electrode (1, 2). Surge protection device according to one of Claims 1 to 4, characterized in that the electrodes (1, 2) have an approach point (4) and an adjoining spark gap (8), such as a horn spark gap. Surge protection device according to Claim 5, characterized in that at the end of the spark gap (8) opposite the approach point (4) at least one electrode element (at least protruding into the space delimited by the electrodes (1, 2), preferably arranged entirely in this space) 9), such as plate, is arranged. Surge protection device according to one of Claims 1 to 6, characterized in that the electrodes (1, 2) are arranged enclosing an acute angle, the approach point (4) preferably being arranged in the first edge region of the electrodes (1, 2) and both supply lines ( 5) spaced from the approach point (4), preferably at the end of the electrodes (1, 2) opposite the approach point (4), so that the at least one movable electrode (1, 2) is caused by force effects caused by the current flow from the other electrode (1, 2) can be moved away. Surge protection device according to Claim 7, characterized in that the electrodes (1, 2) are at least sectionally essentially parallel to one another. Surge protection device according to one of Claims 1 to 8, characterized in that at least one electromechanical actuating element (30) is connected in series with the electrodes (1, 2), which the movable at least one movable electrode (1, 2) in the event of ignition of a Arc between the electrodes (1, 2) moved away from the other electrode (1, 2). Surge protection device according to Claim 9, characterized in that the electromechanical actuating element (30) is designed as a coil (41) with an armature (45) connected in series with the electrodes (1, 2). Surge protection device according to Claim 10, characterized in that the coil (41) is fixed in position and the armature (45) is mechanically connected to at least one movable electrode (1, 2). Overvoltage protection device according to Claim 10, characterized in that the armature (45) is stationary and the coil (41) is mechanically connected to at least one movable electrode (1, 2). Surge protection device according to one of Claims 9 to 12, characterized in that a spring (19) is arranged between the yoke (46) of the coil (41) and the movable electrode (1, 2). Surge protection device according to one of Claims 1 to 13, characterized in that a spacer (39) is arranged between the electrodes (1, 2). Surge protection device according to claim 14, characterized in that the spacer (39) is designed as an electrically non-conductive sleeve, so that the gases heated by the arc move the at least one movable electrode (1, 2) away from the other electrode (1, 2). Surge protection device according to one of Claims 1 to 15, characterized in that a preferably plate-shaped element (12) which cuts through the arc can be introduced into the space delimited by the electrodes (1, 2), preferably in the area of the approach point (4). Surge protection device according to Claim 16, characterized in that the element (12) which cuts through the arc is mechanically connected to the at least one movable electrode (1, 2), for example by means of a rope, a rod or the like. Surge protection device according to Claim 17, characterized in that the element (12) which cuts through the arc can be introduced into the space delimited by the electrodes (1, 2) by means of an electromechanical actuating element (30) through which the arc current flows. Surge protection device according to Claim 16, 17 or 18, characterized in that the element (12) which cuts through the arc is formed from an electrically non-conductive material, such as, for example, ceramic, plastic or the like. Surge protection device according to Claims 1 to 19, characterized in that the electromechanical actuating member (30) or at least one movable electrode (1, 2) actuates a counter. Surge protection device according to claim 20, characterized in that the counter actuates a locking device which holds the electromechanical triggering member (30) or at least one movable electrode in its open position.

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