AU767299B2

AU767299B2 - Multipole switching device

Info

Publication number: AU767299B2
Application number: AU55058/00A
Authority: AU
Inventors: Karl Suchentrunk
Original assignee: Moeller Gebaudeautomation GmbH
Current assignee: Moeller Gebaudeautomation GmbH
Priority date: 1999-09-02
Filing date: 2000-09-01
Publication date: 2003-11-06
Anticipated expiration: 2020-09-01
Also published as: EP1081726A3; ATA151599A; CZ300217B6; DE50005867D1; CZ20003169A3; AT411408B; ATE263423T1; EP1081726B1; EP1081726A2; AU5505800A

Abstract

The device has at least one input and one output terminal per pole path connected together via a connecting line with at least one current measurement device. At least one connecting line contains a switch with rails (1,2) for carrying away a spark between fixed (8) and movable (9) contacts. At least one adjacent line (10) is arranged so that its magnetic field (4',5') augments that (4) in the line with the switch when a spark (3) is present.

Description

P/00/011 28/5/91 Regulation 3.2(2)

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: MULTIPOLE SWITCHING DEVICE The following statement is a full description of this invention, including the best method of performing it known to us MULTIPOLE SWITCHING DEVICE FIELD OF THE INVENTION The present invention relates to a multipole switching device in which arc movement is accelerated by amplifying the magnetic field causing this movement.

BACKGROUND OF THE INVENTION The quickest possible movement away of the arc produced during the separation of the movable and fixed contact is desired in switching devices with such rails acting as spark suppressor devices. A magnetic field is built up by the current flow in the contacts, the rails and the arc, which magnetic field exercises such forces on the arc which try to move the same in the aforementioned manner away from the contacts. In order to accelerate this movement away it is already known to amplify the magnetic field causing this movement by providing currentcarrying conductors.

SUMMARY OF THE INVENTION It is the object of the present invention to provide a multipole switching device of the kind mentioned above in which the acceleration of the arc movement is realised by amplifying the magnetic field causing the movement of the arc with particularly little effort.

In one aspect of the present invention, there is provided a multipole switching device, including: at least two pole paths, each having a connecting lead electrically connecting at least one input terminal to at least one output terminal; at least one measuring device for detecting current flowing in at least one of the connecting leads; 25 switching contacts connected to a first connecting lead of a first pole path of the at least two pole paths; and electrically conducting rails provided adjacent to the switching contacts, wherein the switching contacts and rails are arranged to define a first area in which a first magnetic field is produced by the current flowing in the rails and in an arc produced between the switching contacts or the rails during operation of the multipole switching device, the arc being conducted away by said rails, *oo a second magnetic field is produced by the current flowing in a second connecting lead of a second pole path of the at least two pole paths during operation, the second pole path being adjacent to the first pole path, and the path through the multipole switching device of the second connecting lead is arranged so that the second magnetic field in at least a section of the path amplifies the first magnetic field during the presence of the arc.

Particularly, in the present invention the connecting lead of at least one pole path which is disposed adjacent to the pole path including the switching contact is guided at least in sections in such a way that the magnetic field produced by the current flowing in the same during operation will amplify the magnetic field which is caused n the area marked by the contacts and the rails by the current flowing in the rails and arc during the presence of an arc between the contacts or the rails.

The connecting lead between the input and output terminal of a pole path is a component which exists in the switching device anyway and only needs to be modified slightly in order to realise the advantageous effects of the present invention. This modification consists of the insertions of a lead section such as a stranded conductor or, if such a conductor is already present in the connecting lead, in changing its spatial arrangement which, if necessary, can be accompanied by a slight extension of said stranded conductor. In summary, however, said measures lead to only a slight additional material requirement and can be easily installed in currently existing designs of switching devices.

*It has proven to be particularly appropriate that the connecting lead should extend at least in sections approximately parallel to the area marked by the 25 contacts and the rails in the zone or vicinity of the border or edge of this area.

The magnetic field produced by the current in the connecting lead thus extends in the same direction as the magnetic field produced by the current in the rails and the arc, so that the amplification to be achieved of said magnetic field is produced in a particularly effective manner.

In accordance with a particularly preferable embodiment of the present invention the connecting line is arranged in the form of a conductor loop and is arranged in such a way that the surface area opened by the same is disposed approximately parallel to the surface area defined by the contacts and the rails and covers said surface area at least in sections.

A particularly favourable amplification of the magnetic field produced by the current in the rails and the arc can be achieved in this way with relatively little effort in respect of employed materials.

It has proven to be favourable in this connection that the area defined by the conductor loop overlaps the area defined by the contacts and the rails at least in the zone or vicinity of the contacts and in the zone or vicinity of the sections of the rails directly adjacent to the same.

In order to keep the wear and tear that an arc causes on the contacts as low as possible, it is necessary to conduct the arc away from the zone of the contacts, which is achieved with this kind of arrangement of the conductor loop.

Once the arc is put into motion, no force, or only very little force, is required to maintain said motion. Said low force on the other hand is already exerted by the magnetic field per se which is produced by the current in the rails and the arc, so that the object of a rapid suppression of the arc is already achieved with the arrangement as explained above.

It has been seen that during the usual application of the switching device in low and medium-voltage systems it is sufficient to provide the conductor loop with one winding since the current intensity is sufficiently high here in order to cause the amplification of the magnetic field to be achieved in accordance with the invention by the flow through a conductor loop with only one winding.

In a preferable embodiment of the present invention the multipole S switching device is arranged as a combination of a circuit breaker and fault- 25 current detection circuit. In this case the first pole path is provided for the connection of the phase conductor of a single-phase voltage supply system and includes the measuring device of the circuit breaker (overcurrent detector and short-circuit current detector), the switching contacts triggered by the measuring device by way of a switching mechanism and the electrically conducting rails adjacent to the switching contacts, and the second pole path is provided for the connection of the neutral conductor of the single-phase voltage supply system and includes the components of the fault-current detection circuit (summation current transformer and evaluation circuit connected to its secondary winding).

°*oo The connecting leads of both said neutral conductor pole path as well as the phase conductor pole path are guided through the toroidal core of the summation current transformer.

This preferable multipole switching device is arranged in such a way that the connecting lead of the neutral conductor pole path is formed by a stranded conductor which is arranged in the shape of a conductor loop and is arranged in such a way that the area defined by the same is disposed approximately parallel to the area defined by the contacts and the rails and said area overlaps at least in the zone of the contacts and in the zone of the sections of the rails which are directly adjacent to the same.

As has already been explained above, the amplification of the magnetic field thus to be achieved is produced in a particularly effective way with relatively little effort.

BRIEF DESCRIPTION OF THE DRAWINGS These and other embodiments and advantages of the present invention are now explained in more detail with reference to the accompanying drawings in which: Fig. 1 shows a schematic plan view of two current-carrying rails 1, 2 with an arc 3 burning between the same; Fig. 2 shows a schematic plan view of the contacts 8, 9 of a switching device and two rails 1, 2 adjacent to the same with an arc 3 burning between the same; Figs. 3a-c show the arrangement according to fig. 2 in the same i o representation with a differently arranged conductor 10 for the amplification of the 25 magnetic field produced by the current in the rails 1,2 and the arc 3; :Fig. 4a shows the arrangement according to figs. 3 a-b, with the conductor 10 there being replaced by a conductor loop 11; Fig. 4b shows the arrangement according to fig. 4a with a slightly larger arrangement of conductor loop 11; Fig. 5 shows the top view of a two-pole switching device which is arranged as a combination of a circuit breaker and fault-current circuit breaker; Fig. 6 shows the first pole path 12 of the switching device according to fig.

5 with removed side shell; 4 Fig. 7 shows the second pole path 13 of the switching device according to fig. 5 with removed side shell; Fig. 8 shows the representation of said switching device in the representation according to fig. 6 with omitted separating wall between the two pole paths 12, 13; and Fig. 9 shows the representation of said switching device in the representation according to fig. 7 with omitted separating wall between the two pole paths 12, 13.

DETAILED DESCRIPTION OF THE EMBODIMENTS The present invention is based on the following principle which is known per se and illustrated in fig. 1: Electrically conducting, current-carrying rails are designated with reference numerals 1 and 2, between which an arc 3 is burning. The current through rails 1, 2 and the arc 3 produce an electromagnetic field whose direction is designated with the symbols 4 and 5. Arc 3 is a current-carrying conductor which is located within said field and on which said electromagnetic field exerts a force F. Said force F displaces the arc 3 in its direction, which means to the right in the representation according to fig. 1.

Particularly where switching devices (cf. schematic representation in fig. 2) are concerned, it is desirable to extinguish as rapidly as possible an arc which is produced between two electrically conducting parts which are formed in a switching device by the fixed and movable contact 8, 9 of a break contact in order to actually separate the electric connection between said two contacts.

eeo.

.o o* o o *a One possibility to realise this rapid extinguishing is to arrange the rails 1, 2 in an approximate V-shape (cf. fig. so that the distance between said rails 1, 2 extends with increasing distance from the contacts 8, 9. During the running of the arc 3 to the right which is caused by the force F, the same is extended and will break once it is long enough.

Another very frequently employed method of extinguishing an arc is providing a sparkquenching chamber 6, as is exhibited in fig. 1. Such a device comprises a plurality of small plates 7 which extend approximately parallel with respect to one another and are aligned approximately normal to the arc 3. Once the arc 3 runs into such a spark-quenching chamber 6, it is subdivided by the small plates 7 into a plurality of partial arcs being present between the plates 7 and being connected in series.

To enable an arc to continue to exist it is necessary that it is driven by a specific minimum voltage (=sustain voltage). A voltage required to sustain a series connection of several partial arcs is higher than the voltage required to sustain a single arc having the same entire length.

Once the voltage between the rails 1, 2 is lower than the sum total of the sustain voltages of the partial arcs, arc 3 can be extinguished in the spark-quenching chamber 6 and the electric connection between the rails 1, 2 can thus be interrupted. The movement of the arc into the spark-quenching chamber 6 is achieved by the aforementioned physical fact of the origination of a force F on the arc 3 which is caused by the magnetic field of the current flow in the rails 1,2.

The aforementioned two possibilities of arc extinguishing are combined in conventional switching devices, meaning that the rails 1, 2 are aligned divergent from one another and in the zone of the ends of said rails 1, 2 which are averted from the contacts 8, 9 there is provided a spark-quenching chamber 6, as has been exhibited in fig. 2 with the broken lines.

In order to accelerate the movement of the arc 3 away from the contacts 8, 9 in the direction towards the farther spaced ends of the rails 1, 2 and/or the movement of the arc 3 into the spark-quenching chamber 6 and to thus achieve an even quicker extinguishing of the arc, the magnetic field moving the arc 3 can be amplified in the known manner.

For this purpose a current-carrying conductor 10 is provided which extends in sections approximately parallel to the area A 1 defined by the contacts 8, 9 and rails 1, 2 (cf. figs. 3 a, b, The current flow in said conductor 10 produces a magnetic field designated with reference numerals 5' which overlaps with the magnetic field prevailing within the area If the conduction direction in conductor 10 is chosen in the manner as exhibited in figs. 3 a, b, c, an amplification of the magnetic field will occur in the area A 1 The precise progress of conductor 10 must be chosen in such a way that the discussed effect of magnetic field reinforcement is obtained. Said conductor 10 can therefore be arranged anywhere in the zone outside of area A (cf. figs. 3a, b, The closer it is disposed towards area A, the larger the effect which amplifies the magnetic field in said area A 1 which is why it is preferably arranged in the border zone, e.g. at a small distance resting precisely above one of the two rails 1, 2.

As is exhibited in fig. 4, a conductor loop 11 is preferably used instead of a single, substantially straight conductor 10, which loop is arranged in such a way that the area A 2 as defined by the same is disposed approximately parallel to the area A, as defined by the contacts 8, 9 and the rails 1, 2 and overlaps said area A 1 at least in sections. The conductor loop 11 is therefore disposed coplanarly above the area A. In the area of the overlap of areas

A

1 and A 2 the magnetic field driving the arc 3 in the direction towards the spark-quenching chamber 6 is amplified. The magnetic field produced by the rails 1, 2 and the arc is weakened by the magnetic field produced by the conductor loop 11 outside of this area of overlap, thus leading to a lower running speed of the arc 3 in this area. However, in the arrangement according to fig. 4 this zone which is situated outside of the area of overlap of the areas A 1 and A 2 is already located in the spark-quenching chamber 6, which means in an area in which the arc 3 is disposed shortly before its extinguishing and therefore no longer needs to be moved any more anyway.

The most favourable embodiment of the conductor loop 11 is naturally such, when considering the information as provided above, that the same is provided with an arrangement covering the entire area of A 1 (cf. fig. 4b).

The number of the windings of conductor loop 11 can be chosen at will, because only low forces are required to move the arc 3, which is why it is adequate, as is exhibited in fig. 4 a, b, to provide merely one winding.

The invention aims at providing the discussed conductor 10 or the discussed conductor loop 11 for increasing the running speed of an arc 3 and at implementing this principle in a multipole switching device. An example for such a multipole switching device is shown in figs. 5-9, with reference being made to the same hereinafter: Said multipole switching device is bipolar and is arranged as a combination of a circuit breaker and a fault-current circuit breaker. Every pole path 12, 13 is provided with at least one input terminal 14, 14' and one output terminal 15, 15'. The input terminal 14, 14' of each pole path 12, 13 is electrically connected with the output terminal 15, 15' of said pole path 12, 13 by a connecting lead.

In the pole path 12 which is exhibited in fig. 6 with a removed side shell, the input terminal 14 is connected with the contact bridge 18 by way of a bimetal strip 16 and a flexible stranded conductor 17, which bridge carries the movable contact 9. In the activated state said movable contact 9 rests on the fixed contact 8 which is fixed on the contact carrier 19. Said carrier 19 is connected with the first end of coil 20, whose second end is connected with the output terminal 15 via a further stranded connector 21.

Coil 20 is provided with an armature which is displaceably held in its longitudinal direction and is pressed by the magnetic field of coil 20 against the contact bridge 18 if said coil 20 has a sufficient strength due to a short-circuit current, so that the switching mechanism 26 is triggered and the contact bridge 18 is swivelled by the same. Finally, the movable contact 9 is lifted off from the fixed contact 8 by these processes. Coil 20 with the movable armature forms the short-circuit current detector of the circuit breaker part of the present switching device.

The bimetal strip 16 is heated by the current flowing through it and it will bend such that its end connected with the stranded conductor 17 is swivelled to the right. If an excessive constant current is present, the said bending of the bimetal strip 16 will lead to the consequence that the contact bridge 18 is swivelled by way of the bracket 22 and the movable contact 9 is lifted off from the fixed contact 8. The bimetal strip 16 thus forms the overcurrent detector of the circuit breaker part of the present switching device.

Two measuring devices detecting the current through the connecting line between the input terminal 14 and the output terminal 15 of said pole path 12 are thus situated in said connecting line as well as a switching contact (fixed and movable contact 8, 9) on which the said two current measuring devices act, i.e. they can open the same.

Moreover, electrically conducting rails 1, 2 are provided which are adjacent to the contacts 8, 9 and are used to guide away arcs produced between said contacts 8, 9. A plurality of electrically conductive plates 7 which extend parallel at a distance from one another are provided which form a spark-quenching chamber 6 according to the principle as already explained above.

In the second pole path 13, which is exhibited in fig. 7 with a removed side shell, the connecting line between the input terminal 14' and the output terminal 15' is formed by a continuous stranded conductor 23. Said stranded conductor 23 and the aforementioned stranded conductor 21 which connects the coil 20 of the first pole path 12 with its output terminal 15 are guided through the toroidal core 24 of a summation current transformer. The secondary winding of said summation current transformer is connected with an electronic assembly (indicated by the outline 25 of the printed-circuit board carrying said electronic assembly) which evaluates the signal supplied by the summation current transformer. The electronic assembly is further connected with the switching mechanism acting upon the movable contact 9, so that it can initiate the opening of the break contact 8, 9 of the first pole path 12 when recognising an impermissibly high difference between the currents in the stranded conductors 21 and 23. The second pole path 13 thus contains the components of a fault-current detection circuit, made of a summation current transformer and an evaluation circuit connected to its secondary winding. Said evaluation circuit can naturally be realised in another form, e.g. by a permanent magnet tripping device.

As is clearly shown in fig. 7, the stranded conductor 23 forming the connecting line between the input terminal 14' and the output terminal 15' is provided in the shape of a conductor loop which is provided with one winding. Said conductor loop is arranged in such a way that the area A 2 as defined by the same is disposed approximately parallel to the area A 1 as defined by the rails 1, 2 and overlaps said area A, in sections.

oo Said overlap in sections is shown in particular in figs. 8 and 9 in which all housing parts of the switching device, and in particular the separating wall disposed between the two pole paths 12, 13, were omitted. The zone in which the areas A 1 and A 2 overlap one another is situated here in the zone of the contacts 8, 9 and in the zone of the sections of rails 1, 2 which are directly adjacent to the same.

The first pole path 12 is provided for the connection of the phase conductor L of a two-pole voltage supply system and the second pole path 13 for the connection of the neutral conductor N of said voltage supply system. If during the opening of the switching contact an arc is produced between its contacts 8, 9 or, subsequently, between the rails 1, 2 which are adjacent to said components, said arc ensures that a current will still flow in the neutral conductor N and thus in the stranded conductor 23. Said current flow will therefore lead to the aforementioned amplification of the magnetic field which is produced in the area defined by the contacts 8, 9 and the rails 1, 2 in the presence of an arc between the contacts 8, 9 or the rails 1, 2 by the current flowing in the rails 1, 2 and the arc.

The invention is not limited in any way to the particularly preferred embodiment as exhibited in figs. 6-9. The principle on which it is based consists of realising in a multipole switching device of any desired design, as was already discussed above in connection with figs. 1-4b, the principle of increasing the arc running speed with the help of an already existing connecting line of a pole path which is situated adjacent to a pole path including a switching contact with a downstream arc quenching device.

It follows from this at first that the connecting line need not have the shape of a conductor loop with only one winding. Instead, several windings could also be provided. It is also sufficient within the terms of figs. 3a-c to provide only one section of the conductor loop as provided in figs. 6-9. The other sections of the stranded conductor 23 can be laid at will. Notice must be taken in this connection that it is common practice, by departing from the embodiment as exhibited in figs.

6-9, to also arrange the input terminal 14' of the neutral conductor pole path 13 at the lower border of the device by positioning it next to the input terminal 14 of the phase conductor pole path 12. In order to cause the magnetic field amplification in question it is sufficient to lay the stranded conductor 23 in form of the upper branch of the conductor loop as designated with numeral 23' in fig. 9 or the lower branch thereof designated with numeral 23".

The application of the present invention is not limited to switching devices in which circuit breakers and fault-current circuit breaker functions are combined.

It is possible to realise the principle in accordance with the invention in a multipole switching device provided with only one of the two circuit-breaker functions (three-or four-pole circuit breaker or four-pole fault-current circuit breaker, each provided for a three-phase rotary current system).

In this case it is necessary to provide a switching contact with an arc quenching device not only in one of the pole paths, but at least in all phase conductor pole paths, and mostly also in the neutral conductor pole path. This does not prevent the application of the present invention since in this case too the 25 connecting line of one of the pole paths will be conducted in the aforementioned manner in such a way that the magnetic field will be amplified by the current flow in said connecting line with moves an arc present between the rails 1, 2 of an adjacent pole path.

In this connection it is necessary to note in respect of the two-pole faultcurrent circuit breaker as exhibited in figs. 6-9, that in this case too, the neutral conductor can be provided with an interruptible arrangement, meaning that a switching contact can be built into its pole path 13 according to the design of the "first pole path 12.

Notice should be taken in connection with all possible embodiments, however, that the desired magnetic field amplification will only be obtained when the current in the section of the connecting line used for this purpose has the correct direction of flow. In order to ensure that the switching device in accordance with the invention is connected in the required manner with the voltage supply system and with the conductors to the consumers, it is printed onto the housing of the switching device in the zone of each terminal 14, 15; 14' which conductor must be connected to which terminal 14, 15; 14', Comprises/comprising and grammatical variations thereof when used in this specification are to be taken to specify the presence of stated features, integers, steps or components or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

See.

beo 6 t 0 o• *0

Claims

1. A multipole switching device, including: at least two pole paths, each having a connecting lead electrically connecting at least one input terminal to at least one output terminal; at least one measuring device for detecting current flowing in at least one of said connecting leads; switching contacts connected to a first connecting lead of a first pole path of said at least two pole paths; and electrically conducting rails provided adjacent to said switching contacts, wherein the switching contacts and rails are arranged to define a first area in which a first magnetic field is produced by the current flowing in the rails and in an arc produced between the switching contacts or the rails during operation of the multipole switching device, said arc being conducted away by said rails, a second magnetic field is produced by the current flowing in a second connecting lead of a second pole path of said at least two pole paths during said operation, the second pole path being adjacent to the first pole path, and the path through the multipole switching device of the second connecting lead is arranged so that the second magnetic field in at least a section of said path amplifies the first magnetic field during the presence of said arc.

2. A multipole switching device as claimed in claim 1, wherein at least a section of the second connecting lead is arranged to be approximately parallel to the first area in the vicinity of the edge of the first area. see* o.oo

3. A multipole switching device as claimed in claim 1 or 2, wherein the second connecting lead is arranged to form a conductor loop, said conductor loop being arranged to define a second area disposed approximately parallel to the first area defined by the switching contacts and rails, and said second area being arranged to overlap with at least a section of said first area. 9 9 o* 9 9 9

4. A multipole switching device as claimed in claim 3, wherein the overlap of said first and second areas is provided in at least the vicinity of the switching contacts and the sections of the rails directly adjacent the switching contacts.

A multipole switching device as claimed in claim 3 or 4, wherein the conductor loop is provided with one winding.

6. A multipole switching device as claimed in any one of the preceding claims, wherein the switching contacts include a fixed contact and a movable contact.

7. A multipole switching device as claimed in any one of the preceding claims, wherein said first and second connecting leads are formed by stranded conductors.

8. A multipole switching device as claimed in any one of the preceding claims, wherein said first pole path is provided for the connection of a phase conductor of a single-phase voltage supply system and is arranged as a circuit breaker including said at least one measuring device, said rails, and said switching contacts, the switching contacts being arranged for triggering by the at least one measuring device by way of a switching mechanism included in the multipole switching device, and 20 said second pole path is provided for the connection of a neutral conductor of the single-phase voltage supply system and is arranged as a fault-current detection circuit.

9. A multipole switching device as claimed in claim 8, wherein said fault-current detection circuit includes a summation current transformer and an evaluation circuit connected to the secondary winding of the summation current transformer, and said first and second connecting leads are guided through a toroidal core of the summation current transformer.

O* *ooo**. *o A multipole switching device as claimed in claim 8 or 9, wherein said circuit breaker includes an overcurrent and short-circuit detector.

11. A multipole switching device, substantially as hereinbefore described with reference to the accompanying drawings. DATED this 9 th day of September 2003 MOELLER GEBAUDEAUTOMATION KG WATERMARK PATENT TRADE MARK ATTORNEYS 290 BURWOOD ROAD HAWTHORN VICTORIA 3122 AUSTRALIA P18169AU00 CJS/DCG *O 0