Title of Invention

AN ELECTRICAL SWITCH DESIGNED TO PERFORM BREAKING IN AN ELECTRICAL CIRCUIT

Abstract The present invention relates to a vacuum electrical switch. This switch (I) comprises an elongated vacuum cartridge (1) with a cylindrical enclosure (3a) blanked off by two end-plates (3b, 3c), in which there are housed two arcing contacts respectively stationary (4) and movable (5), and a coil (2) designed to produce an axial magnetic field in the arc formation zone, said coil (2) comprising an end (2b) arranged as a current conducting strip and an end (2a) electrically connected to one (4) of the above-mentioned arcing contacts (4, 5). The above-mentioned two ends (2a, 2b) of the coil (2) are superposed and electrically connected, and a branch-off means (M) , such as for example a magnetic circuit (7), is fitted between these two ends (2a, 2b) to branch off a part of the main current through the coil (2) during breaking in order to create the axial magnetic field.
Full Text



VACUUM ELECTRICAL SWITCH
BACKGROUND OF THE INVENTION
The present invention relates to an electrical switch designed to perform breaking in an electrical circuit, of the kind comprising an elongated vacuum cartridge with a cylindrical enclosure blanked off by two end-plates, in which there are housed two arcing contacts, one, stationary, of which is fixedly secured to one of the above-mentioned end-plates whereas the other, movable, is mounted with axial sliding inside the cartridge, and at least one coil designed to produce an axial magnetic field in the arc formation zone, said coil comprising a first end electrically connected to one of the above-mentioned arcing contacts and a second end arranged as a current conducting strip.
A known circuit breaker (document FR-2,682,808) of the kind mentioned comprises a ring-shaped coil placed in an annular housing formed by the end-plate associated to the coil in such a way that the coil is arranged coaxially outside the cartridge facing the separation gap of the arcing contacts. One of the ends of the coil is mechanically secured and electrically connected to the stationary arcing contact, whereas the other end is electrically connected to a current conducting strip while being electrically isolated from the stationary arcing contact. One of the drawbacks of this type of circuit breaker lies in the fact that as the coil is connected in series with the arcing contacts, the whole of the main current flows through the coil. This results in a coil of large cross-section having to be fitted, which therefore presents considerable overall dimensions.
SUMMARY OF THE INVENTION
The present invention solves these problems and proposes a

switch notably a vacuum switch using a coil for creation of an axial magnetic field, of simple design and small dimensions.
For this purpose, the object of the present invention is to achieve a switch of the kind previously mentioned, characterized in that the above-mentioned two ends of the coil are electrically connected and that it comprises a branch-off means fitted between the above-mentioned two ends to branch a part of the main current off through the coil during breaking, in order to create the above-mentioned axial magnetic field. Advantageously, the two ends of the coil are superposed.
It can already be seen that by means of the invention the coil can be formed by one or more windings of small cross-section.
According to a first embodiment of the invention, the branch-off means comprises a resistive element.
According to a particular feature, this resistive element comprises a resistive washer electrically connecting the above-mentioned two ends of the coil.
According to another embodiment, the above-mentioned branch-off means comprises a magnetic circuit.
According to a particular feature, the magnetic circuit is placed around a conductor electrically connecting the above-mentioned two ends of the coil.
According to another feature, the magnetic circuit comprises at least one air-gap designed to delay branching off of the current until a certain intensity value of the main current has been reached.
Advantageously, branching off in the winding takes place above 8000A.

According to another feature, the coil is formed by a winding whose two ends both extend with an angular offset, parallel to the end-plates of the cartridge.
According to another feature, the first -end of the coil is mechanically secured and electrically ' connected to the stationary arcing contact.
Advantageously, the above-mentioned branch-off means branches off between 10 and 60% of the current into the coil.
The coil and branch-off means are placed inside or outside the vacuum cartridge.
According to a particular embodiment, the coil and branch-off means are placed inside the arcing contact between a conducting rod and an electrode of said contact.
Advantageously, each of the contacts has an associated coil and branch-off means, which are placed inside the vacuum cartridge.

Accordingly the present invention provides an eltfttncal switch designed to perform breaking in an electrical circuit, comprising an elongated vacuum cartridge with a cylindrical enclosure blanked off by two end plates, in which there are housed two arcing contacts one of which, stationary is fixedly secured to one of the end-plates whereas the other, movable, is mounted v^th axial sliding inside the cartridge, and at least one coil designed to produce an axial magnetic field in the arc formation zone, said coil comprising a first end electrically connected to one of the said arcing contacts and a second end arranged as a current conducting strip, characterized in that the two ends of the coil are electrically connected and that it comprises a branch-off means fitted between the two ends to branch a part of the main current off through the coil during breaking, for creating the axial magnetic field.
But other advantages and features of the invention will become more clearly apparent fit)m the following detailed description which refers to the accompanying drawings given for example purposes only and in which;
Figure 1 is a perspective view of a switch according to the invention.
Figure 2 is an axial sectional view of the previous figure, illustrating a first embodiment of the invention.
Figure 3 is an axial sectional view of the figure 1, illustrating a second embodiment of the invention.

Figure 4 is an axial sectional view, illustrating a third embodiment of the invention, and
Figure 5 illustrates, in a perspective view, one of the arcing contacts of the embodiment of figure 4.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In figures 1, 2 and 3, a vacuum switch I can be seen mainly-comprising a vacuum cartridge (or envelope) 1 and a coil 2 coaxially mounted around said cartridge in a manner which will be described by the following. This cartridge 1 comprises an enclosure 3 formed by a cylindrical part 3a closed by two opposite end-plates 3b, 3c. Inside the enclosure 3 there are arranged a stationary arcing contact 4 fixedly secured to one 3b of the above-mentioned end-plates, and a movable arcing contact 5 supported by an operating rod (not represented) passing tightly through the other 3c of the two end-plates. The arcing contacts 4, 5 are disk-shaped and made of a low resistivity material. The coil 2 is in the form of a ring arranged coaxially outside the cartridge 1 facing the gap separating the arcing contacts 4, 5. This coil 2 is formed by a winding and comprises a first and a second end 2a, 2b each extending with an angular offset, parallel to said end-plate 3b associated to the coil 2. The first end 2a is mechanically secured and electrically connected to the stationary contact 4. The second end 2b forms a current conducting strip connected to that of the circuit breaker and is mechanically fixed to the stationary contact 4 by any suitable means, such as a screw passing through aligned holes provided in the above-mentioned two ends 2a, 2b of the coil 2, and screwed into the stationary arcing contact 4.
According to the invention, the switch I comprises in addition a means M, fitted between the above-mentioned two ends 2a, 2b of the coil 2, to branch off a part of the current coming from

the current conducting strip 2b through the winding 2, whereas the complementary part of the current flows through the two ends 2a, 2b and the two arcing contacts 4, 5 until the moment breaking takes place.
According to a particular embodiment' of the invention illustrated in figure 2, this means M is a resistive element 6, in the form of a washer, fitted between the two ends 2a, 2b of the winding 2.
According to another particular embodiment of the invention illustrated in figure 3, this means M is a magnetic circuit 7 disposed around a conductor 8 electrically connecting the above-mentioned two ends 2a, 2b. This magnetic circuit 7 will advantageously comprise one or more air-gaps according to the performances required.
Advantageously for these three different embodiments, between 10 and 60% of the total current in the winding will be branched off, branching off less than 10% being insufficient to achieve breaking whereas branching off more than 60% would be liable to generate an undesirable heat rise.
The operation of the switch I of the invention will be described briefly hereafter successively in its two embodiments illustrated respectively in figures 2 and 3.
This vacuum switch I is particularly designed to perform vacuum breaking in an axial field for a permanent current in the 630A to 3150A range.
According to the embodiment illustrated in figure 2, branching off of the current takes place as soon as the current starts to flow, during breaking, and in linear manner. This branching off generates an axial magnetic field necessary for breaking in the separation zone of the arcing contacts.

It should be noted that this element 6 will advantageously be a washer made of a high resistivity material (stainless steel or other).
According to the embodiment illustrated in figure 3, the magnetic circuit 7 comprises an air-gap and will therefore remain practically inactive up to a certain current intensity value. Up to this value, the current branch-off through the winding 2 will be low. When this value is reached, the magnetic circuit 7 is activated, which will result in a certain quantity of current being branched off through the winding 2, this branch-off creating an axial magnetic field sufficient to achieve breaking.
It should also be noted that this circuit activation value will advantageously be 8000A, a value above which an axial magnetic field is necessary to achieve breaking.
One of the advantages procured by the invention lies in the fact that the winding 2 can remain of small cross-section compared to the cross-section of the conductor 9 through which the permanent current flows, unlike solutions wherein the coil 2 is connected in series with the arcing contacts 4, 5 and conducts almost all of the permanent current. The cross-section of the winding 2 can therefore be reduced, all the more so as when breaking takes place the flow time is short.
Figure 4 illustrates a third embodiment of the invention. In this figure, a vacuum cartridge switch 1 can be seen mainly comprising a cylindrical-shaped insulating enclosure closed by two metallic end-plates 3b, 3c, and housing two arcing contacts 4, 5 respectively stationary and movable extending coaxially inside said enclosure. The two contacts 4 and 5 have the same structure and are both constituted, as can be seen in figure 5, by a conducting rod 10 and a conducting electrode 13 with a coil 12 and branch-off means 11 between the rod and the electrode.

According to the embodiment illustrated in figure 4, this branch-off means is a resistive element 11, but fitting a branch-off means formed by a magnetic circuit could also be envisaged.
Thus, all the means performing generation of an axial magnetic field are located inside the vacuum cartridge. These branch-off means by a high resistivity material or a magnetic circuit branch off between 5% and 60% of the current in the coils. This solution is advantageous for permanent currents ranging from 630A to 3150A. It moreover enables the mechanical strength of the assembly to be considerably improved when applied in a circuit breaker, and furthermore enables the manufacturing costs to be reduced due to a particularly simple construction of the contacts.
The invention will be advantageously applied to electrical switches belonging to the fields ranging from low voltage up to very high voltage.
The invention is naturally in no way limited to the embodiments described and illustrated which have been given as examples only. On the contrary, the invention comprises all the technical equivalents of the means described as well as the combinations thereof if the latter are achieved according to the spirit of the invention.


WE CLAIM:
1. An electrical switch designed to perfonn breaking in an electrical circuit comprising an elongated vacuum cartridge with a cylindrical enclosure blanked off by two end plates, in which there are housed two arcing contacts one of which, stationary is fixedly secured to one of the end-plates whereas the other, movable, is mounted with axial sliding inside the cartridge, and at least one coil designed to produce an axial magnetic field in the arc formation zone, said coil comprising a first end electrically connected to one of the said arcing contacts and a second end arranged as a current conducting strip, characterized in that the two ends (2a, 2b) of the coil (2) are electrically connected and that it comprises a branch-off means (M) fitted between the two ends (2a, 2 b) to branch a part of the main current off through the coil (2) during breaking, for creating the axial magnetic field.
2. The switch according to claim I, wherein the two ends (2a, 2b) of the coil are superposed.
3. The switch according to claim 1 or 2, wherein said branch-off means (M) comprises a resistive element (6).
4. The switch according to claim 1 or 2, wherein said branch-off means (M) comprises a magnetic circuit (7).

5. The switch according to claim 3, wherein the resistive element
(6) comprises a resistive washer electrically connecting the two ends (2a, 2b)
of the coil (2).
6. The switch according to claim 4, wherein the magnetic circuit
(7) is placed around a conductor (8) electrically connecting the two ends (2a,
2b)ofthecoil(2).
7. The switch according to any one of the claims 4 and 6, wherein the magnetic circuit (7) comprises at least one air-gap designed to delay branching off of the current until a certain intensity value of the main current has been reached.
8. The switch according to any one of the preceding claims, wherein the coil (2) is formed by a single winding, said winding comprises two ends (2a, 2b) both extending parallely to the end-plates (3b, 3c) of the cartridge (1), with an angular ofifeet one with respect to the other.
9. The switch according to any one of the preceding claims, wherein the first end (2a) of the coil (2) is mechanically secured and electrically connected to the stationary arcing contact (4).
10. The switch according to any one of the preceding claims, wherein the branch-off means (11) branches off between 10 and 60% of the current into the coil (2).

11. The switch according to any one of the preceding claims,
wherein the coil (2) and branch-off means (M) are place outside the vacuum
cartridge (1).
12. The switch according to anyone of the claims 1 to 11, wherein
the coil (12) and branch-off means (M) are placed inside the vacuum
cartridge (1).
13. The switch according to claim 12 wherein, the coil (12) and
branch-off means (11) are placed inside the arcing contact (4, 5) between a
conducting rod (10) and an electrode (13) of said contact.
14. The switch according to any one of the preceding claims,
wherein each of the contacts (4, 5) has an associated coil (12) and branch-off
means (11) which are placed inside the vacuum cartridge (11).
15. An electrical switch substantially as herein described with
reference to the accompanying drawings.


Documents:

1343-mas-1995 abstract.pdf

1343-mas-1995 claims.pdf

1343-mas-1995 correspondence -others.pdf

1343-mas-1995 correspondence -po.pdf

1343-mas-1995 description (complete).pdf

1343-mas-1995 drawings.pdf

1343-mas-1995 form -1.pdf

1343-mas-1995 form -26.pdf

1343-mas-1995 form -4.pdf

1343-mas-1995 form -9.pdf

1343-mas-1995 petition.pdf


Patent Number 192645
Indian Patent Application Number 1343/MAS/1995
PG Journal Number 30/2009
Publication Date 24-Jul-2009
Grant Date 23-Dec-2004
Date of Filing 17-Oct-1995
Name of Patentee M/S. SCHNEIDER ELECTRIC SA
Applicant Address 40, AVENUE ANDRE MORIZET F-92100 BOULOGNE BILLANCOURT
Inventors:
# Inventor's Name Inventor's Address
1 ROGER BOLONGEAT- MOBLEU 11 IMPASSE FLEMING , 38130 ECHIROLLES,
2 FREDERIC BURNAZ 3 RUE RENE CLAIR, 38130 ECHIROLLES,
3 HANS SCHELLEKENS. 2 ALLEE DU GRAND DUC - 38240 MEYLAN,
PCT International Classification Number HO1H33/66
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA