CH648151A5 - ELECTROMAGNETIC ARC EXTINGUISHING DEVICE. - Google Patents

Description

The present invention relates to an electromagnetic arc extinguishing device for extinguishing an arc burning between two electrodes according to the preamble of claim 1 and to a fuse with such an arc extinguishing device. The present device is suitable for switching operations in any electrical AC and DC circuits, in particular in high-voltage switchgear, including switches, fuses and disconnectors.

In switching operations, in particular in the case of switch-off operations, the extinguishing of the arc is accompanied by the restoration of the original voltage between the electrodes.

Since the arc voltage is U = E-lg = EUN, where E is the arc voltage per unit length of the arc, lg is the total length of the arc to be quenched and EUN is the sum of the voltage drops between the electrodes, there are basically three ways of increasing the voltage of the arc to be extinguished: increasing the number of voltage drops mentioned, increasing the voltage per unit length of the arc and lengthening the arc to be extinguished.

When switching off in AC circuits, there is still the option of extinguishing the arc when the current passes zero, i.e. to restore the electrical strength of the space between the electrodes immediately, which has been followed intensively recently, for example, with vacuum switches that are under development.

The first option, namely the increase in the number of voltage drops between the electrodes, has found widespread use primarily in low-voltage switchgear. For this purpose, the arc to be quenched is subdivided into a plurality of short arcs with their anode and cathode voltage drops using a set of additional electrodes. However, since the amount of the sum of these voltage drops for each of the arcs generally does not exceed a few tens of volts, this option for increasing the voltage of the arc to be quenched is only used as an additional aid in high-voltage switchgear.

For the high-voltage range, starting with voltages higher than 10 to 20 kV, the second possibility for increasing the voltage of the arc to be quenched, namely increasing the arc voltage per unit length of the arc, has come to the fore. This method predominates in oil switches, low oil switches, compressed air switches and SFs switchgear for alternating current. For these voltages, AC switches for higher nominal voltages are used as DC switches.

In these devices, the increase in the arc tension per unit length is achieved by longitudinal, transverse or radial loading of the arc by blowing with a working gas (compressed air or SFô) or by decomposition products of a working liquid (oil). E is a few hundred or even a thousand V / cm, the electrode spacing is a few ten centimeters, the arc length lg can reach about 1 to 2 m, the switch-off voltage for an interruption is a maximum of 100 to 300 kV. However, one of the main disadvantages of all these switching devices remains their low operating speed with switch-off times T of the order of magnitude of usually 0.2 to 0.06 s. In recent developments attempts have been made to bring the shutdown time to 0.02 s using SFô,

Disadvantages of these switching devices are their large dimensions and weights, the complexity of the design and operation associated with the use of special working materials (oil is flammable, compressed air requires compressors, SFô requires a gas-tight construction).

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The third option, namely the extension of the arc to be extinguished, is most often used in switching devices with electromagnetic quenching. In this case, the arc to be quenched moves under the action of a force F based on the interaction between the arc current and a magnetic field, and is extended by means of diverging and distant electrodes (so-called “horns”). The magnetic field is, for example, by separate means, e.g. generated by quenching coils, but use is also made of the magnetic field of the arc current.

Switching devices with electromagnetic extinguishing are simple and reliable in operation and also allow repeated switching operations in the circuits, they do not require any special working medium, have a high working speed that increases with the switch-off current, which makes these switch devices current-limiting when switching off short-circuit currents. After all, they work in switching operations in both AC and DC circuits.

The switching time x in switching devices with electromagnetic quenching is determined by a path covered by the column of the arc to be quenched in the direction of the force F and by the movement speed vg determined by the magnitude of this force F and the movement conditions of the column of arc. So there is x = a / vg. With a flat arrangement of the arc to be quenched, its length can at best only exceed the value a by a small multiple. For example, if the arc has the shape of a semicircle, then lg = Tta. Assuming that Ig ~ U / E, the following relationship is obtained between the switch-off time x and the switch-off voltage U: t = U / kEvg, where k is the ratio between the arc length and the distance covered by the column: k = lg / a means and accordingly depends on the shape of the course of the arc. The value E for a freely moving arc depends on its speed of movement and the arc current and is usually 10 to 100 V / cm. For U = 10 kV and at vg »50 m / s, E« 30 V / cm and k = n, t = 0.02 s and a pro-film ass of the arc quenching device of the switchgear of 2a = s2m.

In order to reduce the dimensions of the arc quenching device, to simplify the operating conditions and to improve the arrangement of its elements, the electromagnetic switching apparatus is generally provided with an arcing chamber having a slot or gap formed by plates made of an insulating material. The quenching chamber specifies the course of the arc to be quenched and its speed of movement, increases the arc tension per unit length of the arc to be quenched by compressing and cooling it, and allows magnetic conductors to be used to intensify the magnetic blowing. Finally, the use of a labyrinth * or zigzag shape of the gap allows the arc to be quenched to be extended further. The possibilities of lengthening the arch with the aid of a labyrinth quenching chamber are limited, however, because the force F driving the arch column and thereby the working speed of the switching device decrease.

To ensure that currents which are lower than the nominal current are switched off when the effectiveness of the magnetic blowing decreases, the electromagnetic switches are usually equipped with their own additional air blower.

The use of labyrinth quenching chambers makes it possible, for example, to create electromagnetic switch-off switches for voltages from 10 to 20 kV with a profile dimension of approx. 1 m and a switch-off time not exceeding 0.06 s. To switch off higher voltages, the switches with electromagnetic quenching have not been used for the time being, because this would require technically unacceptably large dimensions. As a result, the operating speed of the switch drops, i.e. its main advantage there.

The range of working voltages of switches with electromagnetic arc quenching can be expanded if the arc to be quenched turns into a helix with a small pitch Ä. is deformed.

An attempt is known to achieve a helically deformed arc at a switch (see I. Miyachi, H. Naganawa: "Spiral arc in SFs facilitation-DC interruption", III Intern. Conf. Gas Discharges, London, 1974, Page 521).

One after an "electrical explosion", i.e. The explosion-like evaporation due to overloading of a wire connecting the electrodes or after an axial pulling apart of the electrodes or contact pieces in a free arc between the electrodes, which is formed longitudinally with respect to the electrode axis along the longitudinal axis of the electrode, takes the form of a helix which widens in the radial direction. This increases the bow tension. Because of the irregularity of the screw shape of the arc, for example because of the presence of random curvatures of different shapes and dimensions, individual turns of the arc are randomly approximated. This can lead to an electrical breakdown between adjacent turns of the arc, which in turn leads to a sudden drop in the arc voltage.

In the end, the effectiveness of such a helically developing arc does not prove to be high. The ratio of the total arc length to the electrode spacing is 10 to 12 with an outside diameter of the arc screw line of 4 to 6 cm and a pitch of approx. 3 cm.

An electromagnetic arc quenching device is also known (German Patent No. 330268, 1919), in which two electrodes are provided, and means for deforming and radially expanding the arc which is to be ignited and extinguished between the electrodes in a helical shape.

In this known device, the electrodes are arranged on a cylinder made of insulating material and bent in the form of a screw line. To protect the turns of the electrodes from a breakdown, a helical partition wall made of insulating material is provided on the cylinder between the turns of the electrodes, the slope of which corresponds to that of the electrodes.

In the radial direction, the helically deformed arc to be extinguished expands under the action of a force which results from the interaction between the arc current and a magnetic longitudinal field generated by an extinguishing coil arranged inside the cylinder.

When the electrodes move along a helix and in opposite directions, their ends are separated from each other and the arc to be quenched is created between them. Under the effect of the force mentioned, which results from the interaction between the arc current in the areas near the electrodes with the magnetic longitudinal field generated by the quenching coil, the arc winds up on the helical electrodes and assumes the shape of a helix.

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expansion, it moves away from the surface of the cylinder, where the helical partition is no longer able to influence the shape of the arc column and its direction of movement, which can result in an electrical breakdown between adjacent turns of the helical arc. This limits the possibilities of extending the arc to be extinguished and thereby also the level of the working voltage that can be reliably switched off by this known device to a value of at best a few kV with technically justifiable dimensions of the device that are less than 1 m.

A shortcoming of this known electromagnetic arc quenching device is therefore a low value of the working voltage due to a short length of the helical arc formed, namely part of a turn, at best a few turns. In addition, the screw movement of the electrodes for pulling them apart and a screw shape of the electrodes themselves must be provided for the operation of the known device, which complicates the construction.

The present invention is therefore based on the object to provide an electromagnetic arc quenching device of the type mentioned, in which the structural shape of a quenching chamber makes it possible to extend the arc to be quenched during switch-off operations to an extent such as to increase the working voltage given the dimensions of the switching apparatus while maintaining or even increasing their switching speed and thereby being able to use them in various types of high-voltage switchgear.

This object is achieved by the proposed device in that it has the features defined in the characterizing part of patent claim 1. The fuse is defined in claim 7 or 8.

Preferred embodiments of the proposed device are defined in dependent claims 2-6.

The proposed electromagnetic arc quenching device forcibly deforms the arc to be quenched into a helix with a small pitch. This ensures a high degree of compactness of its spatial extent and thus small dimensions of the devices, which is suitable for switching off high working voltages (up to a few hundred kV and above) for both AC and DC current. Here, the distance covered by the column of the arc to be extinguished in the radial direction under the influence of the force resulting from the interaction of the arc current with the magnetic field remains short during the switch-off time (up to approximately 1 m), which means a high operating speed of the device and therefore whose ability to limit the current when switching off short-circuit currents is guaranteed.

The screw shape of the arc to be quenched with the low pitch ensures effective use of the magnetic field of the current of the arc to be quenched itself, which on the one hand increases the working speed of the arc quenching device and on the other hand the design of switches with this device by dispensing with quenching coils and magnetic conductors to simplify in some cases.

The device makes it possible to create high-voltage switches that are able to operate with the oil, oil, air and gas switches that are currently used in this parameter range (voltages from a few tens, hundreds and more kV, currents from a few hundred to a thousand A and more) to compete with SFö gas. Such switches ensure multiple shutdowns of the corresponding circuits, a high working speed (when used in an AC circuit, for example, a one-way power cut-off), are reliable and simple to operate.

The use of the proposed electromagnetic arc extinguishing device in fuses allows simple, cheap and fast-acting protective devices in technically justifiable dimensions to be created for operating voltages of a few hundred kV and above for both AC and DC current.

It is also promising to use the device in fast-acting high-voltage disconnectors with fuse conductors that evaporate in the event of overcurrent (“exploding”), particularly when it comes to disconnections in extremely inductive circuits.

Embodiments of the invention are explained in more detail below with reference to the accompanying drawing. It shows:

1 is an electromagnetic arc extinguishing device in an isometric view,

2 shows a longitudinal section of an embodiment of the arcing chamber in which the space between the turns tapers outwards,

3 shows a longitudinal section of an embodiment of the arcing chamber in which the space between the turns has a zigzag-shaped radial profile,

4 shows a longitudinal section of an embodiment of the arcing chamber with fixing elements between the turns thereof,

5 shows a section along the line V-V of FIG. 4, FIG. 6 shows a longitudinal section of an embodiment with end disks,

7 shows a longitudinal section of an embodiment with a rod made of insulating material arranged in the axial channel,

Fig. 8 is a longitudinal section through a fuse with the proposed device, and

Fig. 9 shows a longitudinal section through a fuse used as a circuit breaker.

The proposed device is described using the example of a switch. As a rule, the device is connected in parallel to the power contacts of the switch, which ensure the current flow in the time between switching operations.

The extinguishing device shown in FIG. 1 has an extinguishing chamber 1 in the form of a helical surface, leaving an axial channel 2 free. Two electrodes (contact pieces) 3, 4 are arranged in the axial channel. The outside diameter of the electrodes 3, 4 is determined by the value of the working current and corresponds to the inside diameter of the axial channel 2. As usual for the electrodes 3, 4, copper, copper-tungsten alloys and the like can be used, for example. The device also has, as usual, quenching coils, not shown, which are, for example, in series with the quenching device and which generate a magnetic field in the quenching chamber 1 indicated by an arrow B in FIG. 1 during a shutdown process. In the device concerned, the magnetic field B is aligned with the axial direction of the arcing chamber 1 and the electrodes 3, 4, i.e. it is a longitudinal field.

The quenching chamber 1 is provided for forcibly specifying the movement in the radial direction of the helically deformed arc 5 to be quenched. In Fig. 1, r is an instantaneous value of a radius of the arc 5 to be extinguished and arrows F indicate the effective directions of the components of the force which result from the interaction between the current of the arc 5 to be extinguished and the magnetic field B. The quenching chamber 1 is formed by an insulating body 6 in the form of a helical surface, the width of the space between the turns of the quenching chamber 1 being indicated by and the slope of the helical surface being indicated by X. The space between the turns fulfills the role of an extinguishing slide5

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zes, the width of which together with the values of the current of the arc 5 to be extinguished and the magnetic field B determine such characteristic data that are present: current density, mass and shape of the cross section of the arc column, the arc voltage per unit length of the arc and finally the speed of movement of the arc column. Therefore, the width of the space between the turns of the quenching chamber 1 can, as usual, be 2 to 10 mm.

The pitch X of the helical area of the quenching chamber 1 is chosen to be as small as possible and is determined by the material, manufacturing technology, operating conditions and service life of the quenching chamber 1, in particular by a minimum permissible thickness (X-A) of the individual turns. The insulating body can be made from various types of insulating materials, in particular from arc-proof and gas-generating insulating materials, for example from a casting resin of the polysulfan, polycarbonate, "Lawsan" type.

The thermal stress on the walls of the quenching chamber 1 in the present construction is below the thermal stress on the walls of the known labyrinth quenching chambers, as a result of securing greater movement speeds for the arch column (as will be added later), and in addition the turns of the quenching chamber 1 are caused by mechanical stresses their bilateral influence on the part of the arc to be extinguished is considerably relieved. For this reason, the requirements for the material from which the quenching chamber 1 is made are lower than the requirements for the material of the known labyrinth quenching chambers.

The present insulating body 6 can be produced by casting or stamping. It is expedient here to carry it out in the form of a set of segments of the turns connected in series. This ensures low manufacturing costs.

The absolute values of the diameter D of the arcing chamber 1 and its length L are determined by the working voltage of the switching device and its working speed. Calculation examples for this are given below. The ratio of the diameter D of the chamber 1 to the pitch X of the helical area must not be below 10 in order to considerably lengthen the arc 5 to be extinguished (by a factor IO2 to 103) compared to the maximum distance of the electrodes corresponding to the length L. 3, 4 to ensure in the off position.

The space between the turns of the insulating body 6 has a rectangular radial profile according to FIG. 1. To further change the arc voltage per unit length of the arc 5 to be extinguished during the shutdown process, i.e. to achieve in the current draw, it is advisable to taper this radial profile to the outside. Such an arcing chamber 7 is shown in FIG. 2, in which the space between the turns has a trapezoidal radial profile.

It is also possible to zigzag the radial profile of the space between the turns of the insulating body of the quenching chamber 8 shown in FIG. 3 or to form the zigzag shape of the quenching chamber 8 or to design the quenching chamber to have a variable pitch X, which allows the movement speed of the arc column to change. A major advantage of the design of the interstice between the turns in the quenching chamber 8 according to FIG. 3 is the possibility of shielding the axial channel 2 of the quenching chamber against the action of the light radiation emanating from the radially expanding arc to be quenched, which restores the electrical strength of the medium accelerated in the axial channel. In addition, the zigzag shape of the radial profile allows

Gap between the turns of the chamber 8 to dampen the sound effect when switched off.

In order to improve the mechanical strength, rigidity and insensitivity to vibrations of the device, in the embodiment of FIG. 4 the device is arranged in the space between the turns of the insulating body 12 of the extinguishing chamber 11 and is rigid with the walls formed by the turns of the insulating body 12 connected fixing elements 9, 10. The quenching chamber 11 also has an axial channel 13 in which electrodes 14, 15 are arranged.

The fixing elements 9, 10 are arranged circumferentially distributed in two rows according to FIG. 5. The fixing elements 9 in one row are cylindrical inserts and the fixing elements 10 in the other row have the shape of ribs.

The fixing elements 9, 10 are made of an insulating material, for example of the same insulating material as the insulating body 12 itself, and are fastened, for example, by gluing.

The arrangement of the fixing elements 9, 10 and their dimensions are determined by the material and the manufacturing technology for these elements 9, 10 and for the chamber 11 and have as little as possible to inhibit the moving arc 16 to be extinguished (FIG. 5). The position of the column of the arc 16 to be extinguished is shown in Fig. 2 at two successive times during its movement in the radial direction, namely at the time of wrapping the fixing elements 9 (with the designation 16a) and when approaching the fixing elements 10 (with the designation 16b).

The fixing elements 9, 10 can also be made of metal. In this case, they additionally fulfill the role of an extinguishing grid which improves the characteristics of the extinguishing chamber 11. However, each of the fixing elements 9 and 10 must be electrically insulated from the rest.

If the insulating body 12 of the extinguishing chamber 11 has a construction that can be assembled, the fixing elements can also serve to connect the individual parts of the extinguishing chamber and to ensure their exact assembly.

In order to enable a shift of the base points of the arc to be extinguished in the radial direction, it is expedient to assign elements of an electrically conductive material to the quenching chamber, for example at the beginning and at the end of the helical space between the windings and additional electrodes extending in the radial direction. These additional electrodes must be electrically connected to the corresponding main electrodes.

Such an embodiment of the device is shown in FIG. 6, which is provided with elements 17, 18 made of an electrically conductive material in order to shift the base points of the arc to be extinguished in the radial direction. These elements 17, 18 have the form of metal disks with axial openings and are arranged on the end faces of the arcing chamber 19. These disks 17, 18 are each electrically connected to an electrode 20, 21 arranged in the axial channel 22 from the same end face. Copper, for example, is suitable as the material for the disks 17, 18.

An arc 23 to be extinguished is shown on the metal disks 17, 18 during its radial expansion and during the displacement of its base points.

7 shows a device for a high-voltage switch. In this device, an immovable electrode 24 (fixed contact piece) is provided, for example in the form of a tube with an inner diameter equal to the diameter of a second movable electrode 25 (movable contact piece). With the movable electronic

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death 25, for example, a rod 26 made of an insulating material is connected by means of a threaded connection.

The diameter of this rod 26 is equal to the diameter of the movable electrode 25 and its length is at least equal to the distance between the electrodes 24, 25 in their switch-off position.

The presence of the rod 26 eliminates the possibility of a breakdown via the axial channel between the electrodes 24, 25 which move away from one another during the switching-off process, which increases the reliability of the operation of the arcing chamber 27.

The material of the rod (arc resistance and gas generation desired) can be different because of its simple shape (for example ceramic, boron nitride, asbestos cement). The movable electrode 24 can also be designed in the form of one or more current take-off terminals.

The position of the arc 28 to be extinguished is shown in FIG. 7 at a moment during the switch-off process in which the arc extinguishing device is active.

The outside diameter of the quenching chamber 27 is expediently to be selected in accordance with the shape of the helical arc-shaped arc 28 to be quenched which is already expanding in the radial direction at the time the shutdown process is ended. The outside diameter of the quenching chamber 27 can taper in the direction of the end face into which the movable electrode 25 engages.

The dimensions and the characteristic mass of the switch can be estimated using the described extinguishing device, for example for a voltage of U = 100 kV. This estimate is made below for a switch with a shutdown time of 5 10 ms in an AC circuit. Assuming that the average speed of movement of the arch column is equal to vg «50 to 100 m / s, the required dimension of the space between two turns and thus the diameter of the quenching chamber are the same

D «2vgx = 1 to 2 m

With an average arc voltage per unit length of the moving, to be extinguished arc E 5 20 to 30 V / cm, the required arc length lg is taking into account a double reserve for the voltage U to be switched off (with regard to overvoltages)

2U

lb = «70 to 100 m E

By constructing the slope À. the helical area is approximately equal to 1 cm and the length L of the quenching chamber is equal to its diameter D is set

D = L = i / I ^ XTk = 0.48 to 0.55 m.

An extinguishing chamber with a dimension D; S 0.55 m and with L <0.55 m is therefore able to switch off a DC or AC circuit with the voltage U = 100 kV (with a double voltage reserve) and with a switch-off time of x <0.01 s without using the elements required for conventional 100 kV switches, e.g. without a 6 to 12 t oil container for an 8 to 15 t oil switch, without a 0.5 to 1.5 t oil container with a 4 to 8 t low oil switch, without a pressure container with a compressor for 2 to 6 MPa for a 5 to 8 ton air switch and finally without a hermetically sealed housing for 0.3 to 0.6 MPa with the SFö gas for one

5 to 8 t pressure gas switch with self-loading, these known switches achieve a switch-off time of a maximum of about 0.06 to 0.1 s and can only be used for alternating current.

8 shows an extinguishing device on a high-voltage fuse. It has an extinguishing chamber 29 which is formed by an insulating body 29 'made of an insulating material. In the axial direction of the chamber, immovable electrodes 30, 31 are arranged on its end faces, which are connected by a fusible conductor 32 made in the form of a wire, for example made of copper.

The fuse element 32 is in the axial channel of the arcing chamber

29 arranged. The diameter of the fuse element

32 equal to the inside diameter of the axial channel.

As is known, the fuses are essentially intended for short-circuit protection and must have a high operating speed. The backup must be fairly simple and cheap. The current high voltage fuses and only up to the voltage level; £

30 to 50 kV functional.

The main element in the fuse shown is the fusible conductor 32, which in this case connects the immovable electrodes and plays the role of power supplies. The effectiveness of the design and the functionality of the fuse are considerably influenced by the ratio of the arc length achieved at the end of the switch-off process to the length of the fuse Fuse element determined.

The construction of the high-voltage fuse shown in FIG. 8 allows practically the highest possible value of this ratio to be obtained by utilizing the fusible conductor 32, the length of which is equal to the length of the arcing chamber 29.

For example, the quenching chamber of the fuse for 100 kV (with double voltage reserve) with a switch-off time of x = 3 ms at X = 1 cm, E = 25 V / cm and vg = 50 m / s has a diameter D and a length L equal to D. = 2vgx = 0.3 m, L = 2U /; iED = 0.9 m and a ratio lg / L = 90.

Such dimensions of the arcing chamber of a fuse for 100 kV are technically justifiable.

FIG. 9 shows a second embodiment of the extinguishing device for a fuse with a fuse element that evaporates under overload. In the axial channel of the arcing chamber

33, a cylindrical insert 34 is arranged, the outer diameter of which is equal to the inner diameter of the axial channel of this arcing chamber 33. A fuse element 35 is wound onto the insert 34 with a slope which is the same as the slope of the helical space between the turns of the insulating body 33 'of the arcing chamber 33. The insert 34 is made of an insulating material, for example the same insulating material as that of the insulating body 33 '. The end faces of the insert 34 enable electrical contact between the fusible conductor 35 and the immovable electrodes 38, 39 of the fuse by means of metal disks 36, 37.

The arc quenching device of such fuses can be designed such that the insert 34 can be replaced after the fuse element 35 has blown. For such a fuse, it is particularly expedient to design the insert to be extendable in the axial direction of the arcing chamber 33 to indicate that the circuit has been switched off after the fuse has been triggered. A new insert 34 with the fusible conductor 35 wound thereon in advance is then screwed into the quenching chamber 33, so that the fusible conductor 35 comes to lie in the space between the turns of the insulating body.

The fuse chamber of the fuse can be used in several ways

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Execute and wrap the insert with as many fusible conductors as there are aisles in the arcing chamber. After triggering, the next fuse element can be switched on by simply rotating the insert or the chamber with the insert by a certain angle.

All described embodiments of the arc quenching device can be combined with other known methods for acting on the arc to be quenched in order to further improve the parameters of switching devices.

For these methods, a change in the working material in the housing of the switch, for example filling it with SFs, or a change in pressure, for example an increase in pressure, and in a number of cases, namely to increase the working speed, conversely, a reduction in pressure or even an evacuation can be expected. In the quenching chamber described, means for increasing the arc burning voltage can also be used, e.g. a set of metal plates which are insulated from one another and arranged at the outlet of the arc extinguishing slot in the direction of movement of the arc column and which represent an extinguishing and deionization grid.

As in the conventional quenching chambers, the helical arc quenching space of the present device can be designed in a radial direction zigzag or laby-rinth, which allows the arc to be quenched to be extended by 1.5 to 3 times with a slight increase in the dimensions of the quenching chamber.

Finally, since all electromagnetic arc extinguishing devices in switches are insufficiently effective when switching off low currents, it is expedient for the proposed device, as is usually the case for known electromagnetic arc quenching chambers, to have its own gas blower for the helical arc-shaped arc quenching space to extend the low-voltage arc to be extinguished.

Such a gas blower, for example an air blower, can supply air through axial openings in the movable and immovable electrode as well as in the rod connected to the movable electrode and blow off air into the helical space between the windings of the quenching chamber via evenly distributed radial openings. Such a blower can also blow off gas via the insulating body of the quenching chamber itself via corresponding openings in the insulating body of the quenching chamber in the vicinity of the axial duct.

A switch with the electromagnetic arc extinguishing device described operates as follows. After a switch-off command has been issued, the power contacts of the switch are pulled apart, whereupon the total current of the circuit flows through the electrodes 3, 4 (FIG. 1) of the device.

The arc 5, which is to be extinguished after the electrodes 3, 4 are pulled apart in the axial channel 2 of the quenching chamber, is located in the longitudinal magnetic field B generated by magnetic coils (not shown). Under these conditions, the arc column changes into a screw shape (cf. in In this connection, the essay "Screw arc instability in the longitudinal magnetic field": El Asinowski, AA Afanasjew, EP Pachomow, contributions of the Academy of Sciences of the USSR, 231, N.2, 1976), whereupon due to the appearance of a tangential component of the current to be quenched Arc arises a radial component of the force of the electromagnetic interaction between arc current and the magnetic field. The effect of this component of the force F causes the entry of the helical arc 5 to be quenched into the space between the turns of the quenching chamber 1 and its expansion in the radial direction.

The radial components of the current of the arc 5 to be extinguished in the regions near the electrodes, in the presence of the longitudinal magnetic field, cause these sections of the arc 5 to rotate in the opposite direction under the action of the tangential components of the force F, which results in a “winding” of the arc 5 to be quenched, and the electrodes 3, 4 after a helical line predetermined by the helical cavity of the extinguishing chamber I. The speed at which the length of the helical arc 5 which widens in the radial direction increases is therefore always greater than the speed at which the electrodes 3, 4 move away from one another.

When the arc to be extinguished is extended to a length at which the arc voltage corresponds to the voltage to be restored at the switch, the current drops to zero. The shutdown process ends.

When switching on, the process of closing the contact takes place in the reverse order as usual: first the electrodes 3, 4 of the extinguishing device close, then the power contact pieces of the switch, not shown in FIG. 1.

The peculiarity of the mode of operation of the quenching chamber I described is the fact that the expansion of the helical arc 5 to be quenched is stable in the radial direction without any significant advance or lag of the individual turns of the arc 5, which affects the interaction of the currents of the adjacent turns with one another (Parallel currents are attracted). Here, the helical insulating body 6 of the quenching chamber 1 is practically relieved of the mechanical stresses because it is exposed to a bilateral action of the arch column 5. An imbalance of the longitudinal component of the force F of the interaction of the turns of the arc 5 to be quenched always points to the center of the quenching chamber 1.

The characteristic data of the proposed arc extinguishing device are approximated by the following expressions for the operating voltage of the arc to be extinguished:

U (t) = nr (t) l (t) E / \

and for the speed of voltage recovery:

5U / 5t = Jtl (t) Evg / A.

given, where r (t) and l (t) denote the radius of the helical arc 5 or its length as a function of time.

The peculiarity of the quenching device described is the need to also take into account the inductance of the quenching arc 5 which is variable over time.

In the embodiment shown in FIGS. 4 and 5, the helical arc 16 to be extinguished, when it extends in the radial direction, will reach the fixing elements 9, will be curved by them and envelop them. This position of the arc to be quenched is designated 16a in FIG. 5. A breakdown occurs between the approaching sections of the arc column 16a behind the bypassed fixing elements 9, and a practically undisturbed, helical course of the arc is formed, which is denoted by 16b in FIG. 5.

In the embodiment of the quenching chamber shown in FIG. 6 with the metal disks 17, 18 on the front side 5

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ten of the chamber 19, the arc 23 to be extinguished, which spreads in the radial and longitudinal directions (by “winding up” on the electrodes 20, 21), reaches these disks 17, 18 upon reaching the end faces of the chamber and assumes a bulbous shape, which can become practically cylindrical. This reduces the erosion of the main electrodes 20, 21, which is usually the case when using horn electrodes.

The mode of operation of the embodiment shown in FIG. 7 differs from that of the one described above only in the first stage. Here, when the electrodes 24, 25 are pulled apart, the rod 26 which is directly attached to the movable electrode 25 and moves together with it is inserted into the axial channel of the arcing chamber 27. If, therefore, when the electrodes 24, 25 are pulled apart, the arc is ignited between them, it immediately forms in the helical gap between the turns of the chamber 27 connecting the pulled electrodes 24, 25. The arc 29 is forced to immediately take on a screw shape. The rod 26 thus allows the screw shape of the resulting arc 28 to be extinguished to be specified immediately and inevitably and does not only cause its entry into the helical space between the turns of the chamber 27 when it is formed.

The helical arc 28 to be extinguished will spread under the effect of the force F in the radial direction and wind up on the electrodes 24, 25 after the helical space between the turns of the chamber 27. Therefore, the action of the arc 28 on the rod 26 is brief, which improves its life.

The characteristic peculiarity of the mode of operation of the quenching chamber 27 is that it specifies the screw shape of the arc 28 to be quenched with a relatively small pitch X and thus transforms the arc to be quenched into a high-current plasma masoloid, which additionally requires that for the operation of the quenching chamber 27 longitudinal magnetic field B builds up, ie a high utilization of the own magnetic field of the current of the to be extinguished

Arc 28 itself effectively guaranteed. The own magnetic longitudinal field of the current turns of the arc to be quenched in the axial direction of the chamber in the example considered above when a current of 5 and 2 kA is switched off at 20 kA at a voltage of 100 kV is 0.2 or 2 T. This means that that the present quenching device allows in many cases a simplification of the construction of the switching apparatus by completely eliminating the magnet coils and magnet conductors. 10 The application of the described arc extinguishing device for fuses and disconnectors with evaporating fuse shows its special features. The device shown in Fig. 8 operates as follows:

After the fusible conductor 32 has burned through, an arc 15 to be extinguished is formed, the arc column of which spreads intensely in the initial period because the conductivity of the plasma is substantially below the conductivity of the metal. Since the spreading of the arc column can only take place in the direction of the helical cavity between the windings of the quenching chamber 29, this leads to the forced formation of the helical shape of the arc to be quenched already in this operating phase of the quenching device.

Furthermore, the helical arc, which is to be extinguished, widens in the radial direction, and is greatly elongated. However, the length dimension of the helical arc to be quenched is always the same as the length of the quenching chamber 29, which further increases the speed of the arc extension and, accordingly, the speed of the voltage recovery between the electrodes.

The functioning of the device shown in FIG. 9 consists in that, on the one hand, the arc 35 to be extinguished after the fusible conductor 35 has burnt through has a helical shape with a predetermined radius and pitch, and on the other hand that the switching current is already in the fusing stage of the fusible conductor 35 generates a significant, own magnetic longitudinal field. This ensures a further increase in the quick action of this extinguishing device.

G

2 sheets of drawings

Claims (9)

648151 1. Electromagnetic arc extinguishing device for extinguishing an arc (5; 16; 23; 28) burning between two electrodes (3,4; 14, 15; 20,21; 24,25; 30, 31; 38,39), with means, in order to deform it in a helical shape and expand it radially, characterized in that an extinguishing chamber (1; 7; 8; 11; 19; 27; 29; 33) formed by an insulating body (6; 12) limited by helical surfaces is provided, the slope ( X) is at least ten times smaller than their diameter (D), and which insulating body (6; 12) has an axial channel (2; 13; 22) in which the electrodes (3, 4; 14, 15; 20) aligned with it , 21; 24, 25; 30, 31; 38, 39) are arranged. 2. Device according to claim 1, characterized in that the space between adjacent turns of the insulating body (6) of the arcing chamber (7) tapers outwards (Fig. 2). 2nd PATENT CLAIMS 3. Device according to one of claims 1 or 2, characterized in that adjacent turns of the insulating body (12) of the arcing chamber (11) are mutually supported by means of fixing elements (9, 10) (Fig. 4, 5) - 4. Device according to one of the claims 1 to 3, characterized in that on the end faces of the arcing chamber (19) electrically with one of the electrodes (20, 21) and radially projecting therefrom, electrically conductive elements (17, 18) are provided are to radially shift the base points of the arc (23) to be extinguished (Fig. 6). 5. Device according to one of claims 1 to 4, characterized in that one of the electrodes (25) in the axial channel of the insulating body of the quenching chamber (27) is slidably arranged in and out of engagement with the other electrode (24) and on its the other electrode (24) facing end carries a rod (26) which fills the axial channel and is made of an insulating material, the other electrode (24) having an axial opening into which the rod (26) engages, the length of which is at least equal to the distance between the electrodes (24, 25) in the off position corresponds (Fig. 7). 6. Device according to claim 5, characterized in that the outer diameter of the quenching chamber (27) tapers in the direction of the displaceable electrode (25) (Fig. 7). 7. A fuse with an electromagnetic arc extinguishing device according to one of claims 1 to 4, in which the electrodes (30, 31) are connected to one another with a fuse element (32) in the form of a wire, characterized in that the fuse element (32) in Axial channel of the insulating body (29 ') of the quenching chamber (29) is arranged and has an outer diameter corresponding to the inner diameter of the axial channel (Fig. 8). 8. A fuse with an electromagnetic arc extinguishing device according to one of claims 1 to 4, in which the electrodes (38, 39) are connected to one another with a fuse element (35) in the form of a wire, characterized in that in the axial channel of the insulating body (33 ') the quenching chamber (33) has an insert (34) which fills it and is made of an insulating material, around which the fusible conductor (35) is wound in the spaces between the turns of the insulating body (33 ') (Fig. 9).