WO2013029657A1

WO2013029657A1 - A quenching chamber for a circuit interrupter

Info

Publication number: WO2013029657A1
Application number: PCT/EP2011/064881
Authority: WO
Inventors: Andreas FRIBERG; Gustavo Dominguez
Original assignee: Abb Technology Ag
Priority date: 2011-08-30
Filing date: 2011-08-30
Publication date: 2013-03-07
Also published as: EP2751824A1; EP2751824B1

Abstract

The present invention relates to a quenching chamber (4) for a circuit interrupter (1) comprising a space (6), and at least two waiis (5) at least partially enclosing the space and positioned on opposite sides of the space. The chamber is configured to comprise, in the space, a switch having a fixed contact (2) and a movable contact (3). Each wall comprises one or more levels (a) of wall units (9), whereby the wall unit within one level extend over a width (w) along a first axis (x) and extend along a part or whole length (I) along a second axis (y) being perpendicular to the first axis, and whereby each wall unit comprises quenching material. The wall units on opposite sides of the space within the same level comprise quenching material having different quenching capabilities. The invention also relates to new combinations of quenching material and use thereof.

Description

Title: A quenching chamber for a circuit interrupter.

THE FIELD OF THE INVENTION

The present invention refers to a quenching chamber for a circuit interrupter according to the pre-characterised portion of claim 1 and a method for quenching an electrical arc according to the pre-characterised portion of claim 14.

BACKGROUND OF THE INVENTION AND PRIOR ART

Electrical current can be interrupted by devices such as switch- es or breakers. A circuit breaker is an example of a device used to interrupt a current upon occurrence of over-heating or over- current. Generally, the switch or breaker comprises a movable contact, which can be separated from a fixed contact to interrupt the current path. An electrica! arc between the contacts may be formed during switching or breaking or a disconnecting operation. An arc voltage is developed across the contacts as the contacts move away from one another during the interruption event. Metal particles may be scattered from the contacts and gases may be released from the material surrounding the con- tacts during the formation of the arc. A pressure may build up inside the switch or breaker by the released gases. The arc event further increases the heat in the switch or breaker. These subsequent events such as pressure building and raises in temperature may result in re-ignition of the arc. Repeated interrup- tion of the current in a switch or breaker is detrimental for the lifetime of the circuit interrupter and may decrement the operational reliability of the interrupter.

The developments for improving switched or breakers have been focused on extinguishing the electrical arc faster by e.g. lowering a peak let through current. Fig 1 shows a schematic plot of an arc event, wherein the current or arc voltage on the y-axis is plotted versus time on the x-axis. When the current exceeds a threshold leve! the contacts move from one another and an arc is formed between the contacts milliseconds after opening of the contacts. Then, the arc dissipates and the current decreases again.

The peak let through current (area B, time zone 2 in Fig 1 ) may be lowered _, by providing dissipating structures such as arc chutes in the switch or breaker to assist in dissipation. US 5,589,672 describes a circuit breaker with an arc quenching device and a vent.

Another way to improve the circuit interrupters involves the use of arc quenching material disposed in the proximity of the contacts. This material may be aligned to the wall of a quenching chamber that surrounds the contacts. Quenching material ablates by the arc during an arc event. The ablation vapors interact with the arc to absorb the arcing energy, thereby cooling the arc temperature and dissipating the arc. Arc quenching materials may be used for lowering the peak let through energy and decreasing re-ignition probability. The material may be used for extending the life of the switch or breaker and improving operational reliability of the interrupter.

Different quenching materials have been used, whereby the different materials influence the arc in different ways. For example, some materials may be capable to ablate rapidly at the start of the arc event (area A, time zone 1 in Fig 1 ). Other materiais may be capable of cooling the environment around the contacts and have more influence on lowering the peak let through current (area B, time zone 2 in Fig 1 ). Yet further materiais may be capable to neutralise the particles present around the contacts after the arc event and have more influence on heat dissipation and neutralisation (area C, time zone 3 in Fig 1 ). Quenching materials may influence one specific area of the curve shown in Fig 1 . However, quenching materia!s may at the same time also influence other areas of the curve.

Quenching material is mostly used to lower the peak let through energy. US 2008/0073326 describes a quenching chamber that includes a vent and quenching material aligned on part of the wall of the chamber to reduce the peak let through current.

US 5,841 ,088 describes a quenching chamber, whereby the walls of the chamber are aligned with two different quenching materials such that the area around the contacts in the chamber is symmetrically surrounded by a first quenching material, and whereby the first material is covered by a second quenching material on the surface that faces away from the contacts. The first quenching material is used to improve the quenching or extinguishing properties, the second material is used to improve the strength against pressure building in the chamber.

US2008/0061037 also describes a quenching chamber for a cir- cuit interrupter comprising a space, and a wail surrounding the space. In the space a switch is present having a fixed contact and a movable contact between which contacts an arc can be generated. The wall of the quenching chamber comprises two or more levels of wall units, whereby the wall unit within one level symmetrically surround the space by extending over the width of the wall along a first axis and extending along a part of the length of the wail along a second axis being perpendicular to the first axis. Each wall unit comprises quenching material, whereby the quenching materials are different in two adjacent levels. One of the quenching materials used provides a relatively high ablation, generating large volumes of ablation vapors to lower the arc temperature and help quenching the arc. The other quenching material used provides a relative low ablation to limit the pressure increase and allowing arc quenching to proceed with less interference from an ablation vapor-induced pressure rise. Operational conditions for switches and breakers vary significantly depending on design, voltage level, current and demands on circuit performances. Arc quenching materials are used to assist electrical interrupters under short circuit conditions. In some cases an interrupter is used to cut off current under normal load. Thus, the operational requirements may be different for circuit interrupters with regard to arc quenching.

There is a need for a quenching chamber, which can be adapted to specific conditions in which the chamber wiM be used. In other words there is a need for a quenching chamber comprising quenching material that can be easily varied and adapted to the specific operational needs of the interrupter. Further, there is still a need for an improved quenching chamber, wherein the electrical arc can be extinguished quicker and whereby the lifetime of the interrupter can be extended. Also, there is a need for improved quenching material.

SUMMARY OF THE INVENTION

The object of the invention is to provide a quenching chamber comprising arc quenching materia! that lowers the peak let through energy, and/or lowers the pressure build and/or de- creases re-ignition probability, it is another object to extend the lifetime of the interrupter. It is a further object to improve the heat resistance in the quenching chamber. It is also an object to improve the operational reliability of the interrupter. It is furthermore an object to provide a quenching chamber, which can easily be adapted to different operational requirement.

The objects are achieved by the quenching chamber initially defined according to the pre-characterised portion of claim 1 , which is characterised in that the wall units (9) on opposite sides of the space (6) within the same level (a) comprise quenching material having different quenching capabilities. The inventors have surprisingly found that the asymmetric alignment of at least two quenching materials that have different quenching capabilities, on opposite wails improves the perfor- mances of the quenching chamber. Firstly, when the rapid ablative material ablates, the vapor gases from this material will push the arc sidewards. Without wishing to be bound by any theories, it is believed that the sidewards bending of the arc inside the quenching chamber as illustrated by the arrow in Fig 2, increases the length of the arc such that more energy is needed to maintain the arc. Thereby, the peak let through energy decreases. The second (and subsequent) quenching material may ablate with reduced quantities of vapor gases such that the pressure build up in the chamber decreases compared to using only the rapid ablative material. Heat resistance is likewise improved because not only rapid ablative materia! is being used but even quenching material, which has excellent cooling and/or neutralisation qualities. As a consequence, the risk for re- ignition of the arc is substantially reduced. Because the extinc- tion of the arc occurs faster, less damage will be caused by the arc, which in turn improved the lifetime of the circuit interrupter. Reduced damage also improves the reliability of the circuit interrupter. Another advantage of the novel quenching chamber is that the quenching materials that have different quenching capabilities, can be easily substituted by other material and thus allow for combining different quenching materials in many different ways. The new chamber can thus be easily adapted for different op- erational requirements such as higher voltages, smaller circuits, etc. In small circuits for example, rapid ablation and cooling may be more important than neutralisation. For such an application the quenching chamber may comprise asymmetric levels comprising materials that rapidly ablate at the start or onset of the arc event and material which has good cooling capabilities (area A and B in Fig 1 ). In one embodiment, the quenching materia! is selected from a first material having ablation capabiiity at a start of a circuit interruption, a second material having cooling capabilities and a third material having neutralisation capabilities, or any mixtures thereof. In another embodiment the first material ablates faster than the second and third material, and the second material cools the space faster than the first and third material, and the third material neutralises faster than the first and second mate- rial.

Using different materials having capabilities within the different regions A, B or C as shown in figure 1 advantageously improves the performance of the quenching chamber. The quenching ma- terials used may have effects in more than one region, but a particular materia! will perform better in one particular region, while another material performs better in a another region. By using the quenching materials that have different quenching capabilities, the quenching chamber is configured to be adapted to the diversity of operational conditions in which the quenching chambers may be used. The ablating sequence of the materials may likewise be varied by the use of different quenching materials on opposite sides of the quenching chamber. This may further improve the performance of the quenching chamber.

In another embodiment, the at least two walls comprise two levels of wall units. In a further embodiment, the at least two walls comprise three levels of wall units, whereby the quenching materials comprised in the middle level has different quenching ca~ pabilities from the quenching material comprised in at least one of the other levels of wall units. Using even more different quenching materials that have different quenching capabilities, in different levels may further increase the speed of ablation, reduce the peak let through energy, improve heat resistance or reduce the pressure build-up. In one embodiment, at least three different walls are present in the chamber, whereby, within one level, the quenching material comprised in the third wall may have the same or different quenching capabilities as the quenching material comprised in one or in both of the two opposite wails. By using two or three different quenching materials that have different quenching capabilities, on three different sides of the chamber within one level, the quenching performance can be further optimised . The quenching chamber can be even more advanced be adapted to the diversity of operational conditions. in a further embodiment, the first material is selected from the group comprising polyacetals, po!yolefms, polyamides and poiy- acrylates, or copolymers or mixtures thereof, and optionally glass materials up to 35 wt% and/or mineral fillers up to 30 wt%. in yet a further embodiment, the second material configured is selected from the group comprising ceramic and thermosetting materials selected from the group comprising epoxy and polyes- ters, or copolymers or mixtures thereof, and optionally including giass materials up to 40 wt% and/ or mineral fillers up to 50 wt%.

In yet another embodiment, the third material is selected from the group comprising polyolefins, polyamids, f!uorinated polymers and thermosetting polymers, or copolymers or mixtures thereof, and optionally including glass materials up to 40 wt% and/ or mineral fillers up to 50 wt%. In one embodiment, the filler is selected from the group

compounds of formula M_m(OH)_n, wherein M is a meta!, m is 0, 1 ,

2 or 3, and n is 0, 1 , 2, 3 or 4, and

compounds of formula G_pH_yCO_x, wherein Q is selected from the group comprising Ca, Na, Mg, Ba and K and p is 0, 1 , 2 or 3, y is 0, 1 or 2 and x is 1 , 2 or 3, and compound of formula T_tR_r, wherein T is selected from the group comprising Ca, Ai, Si, Zr, Ba, Ti, W, Mo, V, g, Zn and B, and R is selected from the group comprising G, S0_4> C and N , wherein t is 1 , 2 or 3, and r is 0, 1 , 2, 3 or 4,

or hydrates or mixtures thereof. in another embodiment, the filler is selected from the group comprising CaO, MgO, ZnO, BaO, Zr0₂, Si0₂, Ti0₂, ZrSi0₄, MgAI₂0_4> Al₂0₃₎ BN, AIM, CN, SIN, TIN, Si₃N₄, SiC, TiC, ZrC, WC, o₂C, VC, B₄C, WSi₂ and MoSi₂, TiB₂, ZrB₂, CaS0₄₎ gS0₄, AI₂{S0₄)₃, Ca(OH)₂, Mg(OH)₂, Zn(OH)₂ and AI(OH}_3> CaC0₃, NaHC0_3> KHC0₃, MgC0₃, BaC0_{3 l} Ca g{C0₃)₂₎ K₂C0₃ and Na₂C0₃, or hydrates or mixtures thereof. The object of the invention is also achieved by a quenching chamber comprising at least two opposite walls whereby, within one level, one wall comprises polyoxymethylene and optionally glass materials up to 35 wt% and/or mineral fillers up to 30 wt% and the opposite wall comprises polymethy!pentene or poiyam- tde 6, 6,6, 1 1 or 12 and optionally glass materials up to 40 wt% and/or mineral fillers up to 50 wt%.

The objects are further achieved by a switch comprising the quenching chamber as described above.

The object of the present invention is also achieve by a method initially defined according to the pre-characterised portion of claim 14, characterised in that the wail units on opposite sides of the space within the same level comprise quenching material having different quenching capabilities.

In one embodiment of the method the quenching material comprises quenching capabilities selected from a first material having ablation capability at a start of a circuit interruption, a se- cond material having cooling capabilities and a third material having neutralisation capabilities, or any mixtures thereof. In another embodiment of the method the quenching chamber is defined as described in any one of the embodiments above. BRI EF DESCRIPTION OF THE DRAWINGS

Fig 1 shows a schematic plot of the current or voltage versus time.

Fig 2 shows a schematic view of the quenching cham- ber with one levei of wall units surrounding the space and quenching materials that have two different quenching capabilities.

Fig 3a and 3b shows a schematic view of the quenching chamber with two levels of wall units surrounding the space and quenching materials that have two different quenching capabilities.

Fig 4 shows a schematic view of the quenching chamber with one level of wall units surrounding the space and quenching materials that have three different quenching capabilities.

ig 5 shows a schematic view of the quenching chamber with two levels of wall units surrounding the space and quenching materials that have four different quenching capabilities.

ig 6 shows a schematic view of the quenching chamber with one level of wall units enclosing the space and quenching materials that have two different quenching capabilities.

ig 7 shows the effect on arc voltage versus time of the novel combination of quenching materials. ig 8 shows the effect on arc gap conductance versus time of the novel combination of quenching materials. DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

Fig 2 shows a circuit interrupter 1 comprising a contact with a fixed contact 2 and a movable contact 3. The contact is surrounded at least partly by a quenching chamber 4, The chamber 4 may comprise one, two, three or four walls 5, Fig 2 shows a quenching chamber 4 with three wal!s 5, whereby the walls 5 define a space 6 and a contact area 7 within this space 6. An electrical arc 8 may be generated when the contacts 2, 3 separate from one another. The wails 5 are positioned such that the arc 8 is exposed to the wail 5. The wails 5 may comprise more than one level a, b of wall units 9. As shown in figs 3a and 3b, the wall unit 9 within one level a extend over a width w of the wall 5 along a first axis x and extend along a part or whole length I of the wall 5 along a second axis y being perpendicular to the first axis. The different levels a, b are adjacent to one another. At least two of the wails 5a in the chamber 4 are positioned on opposite sides of the space 6, i.e. on opposite sides of the contact area 7. See fig 2 to 6.

Each wall 5 may comprise one or more wall units 9 at one or more levels a, b. Each wa!i 5 may be divided in two, three, four or five units 9. Fig 4 shows a chamber 4 with three walls 5, whereby each wall 5 comprises one unit 9 at one level a. Fig 5 shows a chamber 4 with three walls 5, whereby each wall 5 comprises two wa!! units 9 at two levels a, b.

The wall units 9 comprise quenching material. The wall units 9 within one wall 5 may comprise the same quenching material (fig 3a) or different units 9 within one wail 5 may comprise different quenching materials at different levels a, b (fig 3b). The quenching materia! on opposite walis 5 or sides of the space 6 in the quenching chamber 4, within at least one level a, comprises quenching material having different quenching capabilities. For example, the chamber 4 may comprise two walls 5a with three levels a, b, c of wail units 9, whereby the quenching materia! comprised in the midd!e levei b on one wall 5a has different quenching capabilities compared to the material comprised in the middle level b on other opposite wall 5a. The quenching materia! comprised in one of the other levels a, c of wall units 9 may be the same or different from the quenching materials comprised in middle level b on either one of the opposite walis 5a.

The quenching chamber 4 may comprise three different walls 5a, 5b, whereby, within one level a, the quenching materia! comprised in the third wall 5b may be the same as the quenching material comprised in one of the two opposite walls 5a. The quenching material comprised in the third wall 5b, within one level a, may also be the same as the quenching materia! com- prised in both of the two opposite walls 5a. (Fig 3) The third waii 5b may thus be divided and comprise different quenching materials within one levei a. The quenching material comprised in the third wall 5b, within one level a, may aiso be different from the quenching material comprised in both opposite walls 5a. (Fig 4, 5)

The walls 5 may be aligned with quenching material. The walls 5 may a!so be made of the quenching material, In some interrupters quenching chambers 4 may be used, whereby the wails 5 are partiy made of quenching materia! and partly made of other material, which may be aligned with quenching materia!.

With reference to fig 1 , the different quenching materials may ablate at different voltages, temperatures or time intervals. Quenching material can be made to ablate under certain conditions. For example, a first ablating or quenching materia! (area A in fig 1 ) may, quickly after opening of the contact, i.e. at the start of the circuit interruption, ablate a vapor gas in the chamber 4. A second material may ablate at increased temperature to cause a cooling effect (area B in fig 1 ). Yet further a third mate- rial may ablate at a later time interval to neutralise the environment in the space 6 of the chamber 4 (area C in fig 1 ). The vapor gas of the first quenching material will push the electrical arc aside as indicated by the arrow in fig 2. Increasing the length of the arc assists in quenching or extinguishing the arc. A second ablative material may cool the vapor particles in the chamber 4, while a third quenching material may be used to neutralise the vapor in the space 6 of the chamber 4.

Important is that the quenching chamber 4 is asymmetrically aligned with quenching material such that the quenching material in the walls 5a, which are positioned on opposite sides of the space 6, within at least one level a, have different quenching capabilities. Thus, within at least one level a of wall unit 9 on one wail 5a, the quenching material is selected from a first ma- terial having ablation capability at a start of a circuit interruption, i.e. material which rapidly ablates or a second material having cooling capabilities or a third materia! having neutralisation capabilities, while the quenching material on the opposite wall 5a, within the same level a is selected from the first or se~ cond or third material, but whereby the material on this opposite walls 5a have different quenching capabilities. In one embodiment, the quenching capabilities of the materia! on one wall 5a is a mixture of one or more of the first, second and/or third material and the material on the opposite wall 5a is selected from one of the first, second or third material, and has different quenching capabilities. In another embodiment, both walls 5a comprise mixtures of one or more of the first, second and/or third material, whereby the capabilities are different on the opposite walls 5a of the space 6. The quenching capabilities of the material comprised in the other levels may be the same or different as the capabilities of the material on the one level having the different quenching capabilities on opposite walls 5a. The quenching material comprised in the other levels may be different and have different quenching capabilities or the material may be different but have the same quenching capabilities.

The quenching material comprised in the third wall 5b may be the same or different as the quenching material on two opposite walls 5a. The different material may have different quenching capabilities or the material may be different but have the same quenching capabilities. For example, the quenching chamber 4 may comprises three walls 5a, 5b, whereby, within the same level a, each wall 5a, 5b comprises a quenching material having quenching capabilities different from the capabilities in the other two walls 5a, 5b. (Fig 4 and 5) All possible combinations are included in the scope of this patent application as long as the quenching materials on the opposite walls 5a, at least within one level a of wall units 9, comprise quenching materials having different quenching capabilities.

A first quenching material configured for rapid ablation at the start of the interruption may be selected depending on the oper- ationa! conditions for the circuit interrupter and may be selected from the group comprising polyaceta!s, polyolefins, poiyamides, polyacrylates or copolymers or mixtures thereof, and optionally glass materials up to 35 wt% and/or mineral fillers up to 30 wt%. Polyacetals may be defined as alkanes comprising an oxy molecule in the main chain. Examples of polyacetals are poiyox- ymethylene and polyvinylaceta!, or copolymers or mixtures thereof. Another example is ethylene vinyl acetate. In one embodiment the first materia! is poiyoxymethyfene. in another em- bodiment the first materia! is polyvinylacetal. In a further embodiment the material is a copolymer of polyoxymethylene. Examples of polyoiefines are polyethylene, polypropylene, polymethylpentene, cycloolefine and polybutylene, or copolymers or mixtures thereof, in one embodiment the first material is polyethylene, in another embodiment the first material is polymethylpentene. In a further embodiment the material is polypropylene. In yet another embodiment the first material is poly- butyiene. Examples of polyamides are poiyamide 6, polyamide 6T, poly- amide 6,3 polyamide 6,4, polyamide 6,6, polyamide 1 1 , poiyamide 12 and polyamide 6, 10, or copolymers or mixtures thereof. In one embodiment the first material is polyamide 6. In another embodiment the first material is polyamide 6T. in one embodi- ment the first material is polyamide 6,4. I n yet another embodiment the first material is polyamide 6,6. In yet a further embodiment the material is polyamide 1 1 . In another embodiment the first material is polyamide 12. Examples of polyacryiates are poiymethylmetacrylate, polyeth- y!metacry!ate and polyacry!onitrile. in one embodiment the first material is poiymethylmetacrylate. In another embodiment the first material is poSyethylmetacrylate. The first quenching material, including any one of the single compounds mentioned above, or copolymers or mixture thereof or copolymers of such mixtures, may be combined with glass materials up to 40 wt% and/or mineral fillers up to 30 wt%. Thus, the first quenching material may comprise 0 wt%, or up to 10 wt%, 20 wt% or 30 wt% glass material, or between 5 and 40 wt%, or 5 and 30 wt% , or 5 and 20 wt%. The material may further comprise mineral fillers up to 30 wt%, or 20 wt%, or 10 wt%, or between 1 and 15 wt% , or 5 and 15 wt%. Examples of the first quenching material may be a polyethylene including be- tween 0 to 30 wt% glass material and between 0 to 15 wt% filler. Or polypropylene including between 0 to 30 wt% glass material and between 0 to 15 wt% filler. Or polybutylene including between 0 to 30 wt% glass material and between 0 to 20 wt% filler. Or polymethyipentene including between 0 to 30 wt% glass material and between 0 to 10 wt% filler. Or po!yamide 6 including between 0 to 30 wt% glass materia! and between 0 to 15 wt% filler. Or poiyamide 6,4 including between 0 to 30 wt% glass material and between 0 to 15 wt% filler. Or poiyamide 6,6 including between 0 to 30 wt% glass material and between 0 to 15 wt% filler. Or poiyamide 1 1 including between 0 to 30 wt% glass ma- terial and between 0 to 20 wt% filler. Or poiyamide 12 including between 0 to 30 wt% glass material and between 0 to 15 wf% filler. Or po!yoxymethylene including between 0 to 30 wt% glass material and between 0 to 20 wt% filler. Or a copolymer of poiy- oxymethyiene including between 0 to 30 wt% glass material and between 0 to 15 wt% filler. Or poly methylmetacry late including between 0 to 20 wt% glass material and between 0 to 20 wt% filler.

A second quenching material configured for cooling may be ce- ramie or thermosetting materials selected from the group comprising epoxy and polyesters; or copolymers or mixtures thereof, and optionaily including glass materials up to 40 wt% and/ or mineral fillers up to 50 wt%. Thermosetting materials may be selected from the group comprising epoxies of bisphenoSe type, novalak type or alicyclic type, ester type, amino type and phenolic type, or copolymers or mixtures thereof. Examples of bisphenole epoxies may be bi- spheno!e~a type epoxy, bisphenole-f type epoxy.

Amino type and phenolic type epoxies may be unsaturated polyesters.

Polyesters may be polyethyleneterphtalate or polybuty!ene- terphtalate, or copolymers or mixtures thereof.

The second material, including any one of the single compounds mentioned above, or copolymers or mixture thereof, or copoly- mers of such mixtures, may be combined with glass materials up to 50 wt% and/or mineral fillers up to 50 wt%. Thus, the second quenching materia! may comprise 0 wt%, or up to 20 wt%, or 30 wt%, or 40 wt%, or 50 wt% glass material, or between 5 and 45 wt%, or 10 and 30 wt%. The material may further comprise mineral fillers up to 40, or 30, or 20, or 10 wt%, or between 5 and 40 wt%, or 10 and 40 wt%, or 5 and 30 wt%. Some examples may be a bisphenole-a type epoxy including between 0 to 40 wt% glass material and between 5 to 40 wt% filler. Or bi- sphenole~f type epoxy including between 0 to 40 wt% glass material and between 5 to 40 wt% filler. Or amino type unsaturated polyesters including between 0 to 40 wt% glass material and between 5 to 40 wt% filler. Or phenolic type unsaturated polyesters including between 0 to 40 wt% glass material and between 5 to 40 wt% filler. Or novaiak type including between 0 to 40 wt% glass material and between 5 to 45 wt% filler. Or aSicyclic type including between 0 to 40 wt% glass material and between 5 to 35 wt% filler. Or ester type including between 0 to 40 wt% glass material and between 5 to 45 wt% filler.

A third quenching material configured for neutralising may be selected from the group comprising polyolefins, polyamids, fluor- inated polymers and thermosetting materials, or copolymers or mixtures thereof, and optionally including glass materials up to 40 wt% and/ or mineral fillers up to 50 wt%.

Polyolefins may be polyethylene, polypropylene, polymethylpen- tene, po!ybutylene, or copolymers or mixtures thereof. Polyamides may be selected from the group comprising polyam- ide 6, polyamide 6T, polyamide 6,3, polyamide 6,4, polyamide 6,6, polyamide 1 1 , polyamide 12, polyamide 6,10, or copolymers or mixtures thereof. Fluorinated polymers may be selected from the group comprising polytetrafluoroethylene, polyvinyifluoride, po!yvinylidenefluo- ride, poiyperfiuoroa!koxy, polyfiuormatedethylenepropyiene, or copolymers or mixtures thereof.

Thermosetting materials may be selected from the group com- prising epoxles of bisphenole, novalak or alicyclic or ester type, or copolymers or mixtures thereof, and unsaturated polyester of amino type or phenolic type, or copolymers or mixtures thereof, and optionally glass materials up to 40 wt% and/ or mineral fillers up to 50 wt%.

Polyester may be polyethy!eneterphtalate or polybuty!ene- terphtalate, or copolymers or mixtures thereof.

The third quenching material, including any one of the single compounds mentioned above, or copolymers or mixture thereof or copolymers of such mixtures, may be combined with glass materials up to 40 wt% and/or mineral fillers up to 50 wt%. Thus, the third quenching material may comprise 0 wt%, or up to 10 wt%, 20 wt% or 30 wt% glass material, or between 5 and 40 wt% , or 5 and 30 wt%, or 5 and 20 wt%. The materia! may further comprise mineral fillers up to 50 wt%, 40 wt%, 30 wt%, or 20 wt%, or 10 wt%, or between 1 and 50 wt%, or 5 and 45, or 0 and 40 wt%, or 5 and 35 wt.%. Examples of the third quenching material may be a polyethylene including between 0 to 30 wt% glass material and between 0 to 35 wt% filler. Or polypropylene including between 0 to 30 wt% glass material and between 0 to 25 wt% filler. Or polybuty!ene including between 0 to 30 wt% glass material and between 0 to 20 wt% filler. Or poiymethylpen- tene including between 0 to 30 wt% glass materia! and between 0 to 10 wt% filler. Or polyamide 6 including between 0 to 30 wt% glass material and between 0 to 15 wt% filler. Or polyamide 6,4 including between 0 to 30 wt% glass material and between 0 to 15 wt% filler. Or polyamide 6,6 including between 0 to 30 wt% glass material and between 0 to 15 wt% filler. Or polyamide 1 1 including between 0 to 30 wt% glass material and between 0 to 20 wt% filler. Or polyamide 12 including between 0 to 30 wt% glass material and between 0 to 15 wt% filler. Or bisphenole-f type epoxy including between 0 to 40 wt% glass materiai and between 5 to 40 wt% filler. Or polyvinyiidenefluoride including between 0 to 20 wt% glass material and between 0 to 20 wt% filler.

The filler may be metal hydroxides such as compounds of formula M_m(OH)_n, wherein M is a metal, m may be 0, 1 , 2, 3 or 4 and n may be 0, 1 , 2, 3 or 4. In one embodiment m is 1 , 2 or 3 and n is 1 , 2, 3 or 4. In another embodiment m is 1 or 2 and n is 1 , 2 or 3. Examples of metal hydroxides may be selected from the group comprising Ca(OH )₂, Mg(OH )₂, Zn(OH)₂ and Ai(OH)₃, or hydrates or mixtures thereof. Hydroxides may be advantageously used for neutralising the environment in the quenching cham- ber. For exampie a polyamide (e.g. polyamide 6, 6,6, 6,4 or 12) or a polyolefin (e.g. polyethylene or polymethy!pentene) together with a glass reinforced epoxy may include 1 0 to 40 wt% A!(OH)₃ and/or its hydrates, or 10 to 40 wt% g(OH)₂ and/or its hydrates. Or a polyamide (e.g. polyamide 1 1 or 6, 10) or a poly- acrylate (e.g. po!ymethylmetacrylate) together with a glass reinforced epoxy may include 10 to 40 wt% Zn(OH)₂ and/or its hydrates, or Ca(OH)₂ and/or its hydrates.

The filler may also be a carbon oxide releasing compound, which may be a carbon oxide or carbon dioxide or carbon triox- ide. Examples are compounds of formula Q_pH_yCO_x, wherein Q may be an organic or inorganic compound selected from the group comprising Ca, Na, Mg, Ba and K and p may be 1 , 2 or 3, y may be 0, 1 or 2 and x may be 1 , 2 or 3. These carbon oxide releasing compound may be selected from the group comprising CaC0₃, NaHC0_{3 >} KHCO₃, MgCO₃, BaC0₃, CaMg(C0₃)₂, K₂C0₃ and Na₂C0₃, or hydrates or mixtures thereof. For example a polyamide (e.g. polyamide 6, 6,6 or 12) or a polyolefin (e.g. polyethylene or polymethylpentene) together with a glass rein- forced epoxy may include 10 to 40 wt% MgCO₃ and/or its hydrates, or CaMg(C0₃)₂ and/or its hydrates. Or a polyamide (e.g. po!yamide 6, 1 1 or 12) or a polyoiefin (e.g. polyethylene or polymethy!pentene) together with a glass reinforced epoxy may include 10 to 40 wt% CaC0₃ and/or its hydrates, or BaC0₃ and/or its hydrates. Or a polyamide (e.g. polyamide 6, 6,6, 1 1 or 12) or a poiyolefin (e.g. polypropylene or po!ymethylpentene) together with a glass reinforced epoxy may include 10 to 40 wt% KHC0₃ and/or its hydrates. Or a polyamide (e.g. polyamide 6,4 or 6, 10) or a polyacrylate (e.g. polymethylmetacrylate) together with a glass reinforced epoxy may include 10 to 40 wt% K₂C0₃ and/or its hydrates.

Other fillers that may be used are compound of formula T_tR_r, selected from oxides, carbides, nitrides, silicides, borides and sulphates, wherein T may be selected from the group comprising Ca, Al, Si, Zr, Ba, Ti, W, Mo, V, Mg, Zn and B, and R may be selected from the group comprising O, S0₄, C and N , wherein t may be 1 , 2 or 3, and r may be 0, 1 , 2, 3 or 4. In one embodiment, t is 1 , 2 or 3 and r is 1 , 2, 3 or 4. The compound of formula T_tR_r may be selected from the group of oxides comprising CaO, MgO, ZnO, BaO, Zr0₂, Si0₂, Ti0₂, ZrSi0₄, MgAI₂0₄ and Af₂0₃. Or the compound of formula T_tR_r may be selected from the group of nitrides comprising BN, AIN, CN, SiN, TiN and Si₃N₄. Or the compound of formula T_tR_r may be selected from the group of carbides comprising SiC, TiC, ZrC, WC, Mo₂C, VC and B C. Or the compound of formula T_tR_r may be selected from the group of silicides comprising WSi₂ and MoSi₂. Or the compound of formula T_tR_r may be selected from the group of borides comprising TiB₂ and ZrB₂. Or the compound of formula T_tR_r may be selected from the group of sulphates comprising CaS0₄, MgS0₄ and AI₂(S0₄)₃ For example the quenching material may comprise a polyoiefin with 2 to 7 wt% of a boride filler such as polymethylpentene with 3 wt% TiB₂. Or polybutylene with 7% ZrB₂. Or polypropylene with 5 wt% TiB₂. Or a polyoiefin with 2 to 7 wt% of an oxide filler such as polymethylpentene with 3 wt% MgO. Or polybutylene with 7% ZnO. Or a polyolefin with 2 to 7 wt% of a nitride filler such as polybutylene with 5 wt% TiN, or polypropylene with 5 wt% BN, or po!ymethylpeniene with 5 wt% AIN, Or a polyolefin with 2 to 7 wt% of a carbide filler such as polypropylene with 5 wt% SiC, or poiybutylene with 5 wt% B₄C. Or a polyolefin with 2 to 7 wt% of a si!icide filler such as poly- butylene with 5 wt% WSi₂, or polypropylene with 5 wt% oSi₂. Or a polyolefin with 2 to 7 wt% of a sulphate filler such as poiybutylene with 5 wt% CaS0₄, or polyethylene with 5 wt% MgSO₄.

The quenching material may also comprise a polyamide with 2 to 7 wt% of a boride filler, such as polyamide 6 or polyamide 12 with 5 wt% TiB₂. Or a polyamide with 3 to 7 wt% of an oxide filler such as polyamide 6.6 with 5 wt% A!₂0₃ Or a polyamide with 2 to 7 wt% of a nitride filler such as polyamide 6 or polyamide 6.6 with 5 wt% AIN, or polyamide 12 with 5 wt% BN . or polyam- ide 6T with 5 wt% Si₃N₄. Or a polyamide with 2 to 7 wt% of a carbide filler such as polyamide 6,4 or polyamide 12 with 5 wt% SiC, or polyamide 1 1 with 5 wt% B₄C. Or a polyamide with 2 to 7 wt% of a siliclde filler such as polyamide 1 1 with 5 wt% WSi₂, or polyamide 12 with 5 wt% oSi₂. Or a polyamide with 2 to 7 wt% of a sulphate filler such as polyamide 6 with 5 wt% CaSO₄, or polyamide 6,4 with 5 wt% MgSO₄.

The quenching material may also comprise a fiuorinated polymers with 2 to 7 wt% of a boride filler, such as poiytetrafluoro- ethylene with 5 wt% TiB₂. Or a fluorinaied polymers with 3 to 7 wt% of an oxide filler such as polyperfiuoroalkoxy with 5 wt% AI₂O₃ Or a fiuorinated polymers with 2 to 7 wt% of a nitride filler such as po!ytetrafiuoroethylene with 5 wt% AIN , or poiyviny!i- denefluoride 5 wt% BN, or polyperfiuoroalkoxy 5 wt% Si₃N₄. Or a fiuorinated polymers with 2 to 7 wt% of a carbide filler such as polyperfiuoroalkoxy with 5 wt% SiC, or polyvinylidenefluoride with 5 wt% B₄C. Or a fiuorinated polymers with 2 to 7 wt% of a silicide filler such as poiyfluorinatedethylenepropylene with 5 wt% WSi₂, or polyvinylidenefluoride 5 wt% oSi₂. Or a f!uorinat- ed polymers with 2 to 7 wt% of a sulphate filler such as polyfluorinaiedethylenepropyiene with 5 wt% CaS0₄, or poiyvi- nylf!uoride with 5 wt% MgS0₄.

The quenching material may also comprise a thermosetting ma- terial with 2 to 7 wt% of a boride filler, such as bisphenoie-f type epoxy with 5 wt% ZrB₂, or novalak type with 5 wt% TiB₂. Or a thermosetting material with 3 to 7 wt% of an oxide filler such as aiicyclic type epoxy with 5 wt% Al₂0₃ Or a thermosetting material with 2 to 7 wt% of a nitride filler such as amino type unsatu- rated polyester epoxy with 5 wt% A!N, or aiicyclic type 5 wt% 8N, or bisphenole-a type epoxy 5 wt% Si₃N₄. Or a thermosetting material with 2 to 7 wt% of a carbide filler such as aiicyclic type epoxy with 5 wt% SiC, or bisphenole-f type epoxy with 5 wt% B₄C. Or a thermosetting material with 2 to 7 wt% of a silicide fiiler such as alicyciic type epoxy with 5 wt% WSi_{2 i} or ester type epoxy 5 wt% MoSi₂. Or a thermosetting material with 2 to 7 wt% of a sulphate filler such as phenolic type unsaturated polyester epoxy with 5 wt% CaSO₄, or bisphenole-a type epoxy with 5 wt% MgSO₄.

.

The fiiler may also be any mixture of any of the fii!ers mentioned above. The mineral filler may be selected from CaO, MgO, ZnO, BaO, ZrO_{2 l} SiO₂₎ TiO₂, ZrSiO_{4 l} MgAI₂O₄, Ai₂O₃, BN, AIN, CN, SiN, TIN, Si₃N₄, SiC, TIC, ZrC, WC, Mo₂C, VC, B₄C, WSi₂ and oSi_{2 )} TiB₂, ZrB_{2 s} CaSO₄, gSO₄₎ AI₂{SO₄}₃, Ca(OH)_{2 >} Mg(OH)_2l Zn(OH)₂, AI(OH)₃, CaCO₃, NaHCO₃, KHC0₃, MgCO₃, BaCO_3l CaMg(C0₃)₂, K₂CO₃ and Na₂CO₃ or hydrates or mixtures thereof. Or the mineral filler may be selected from MgO, ZnO, AI₂O₃, BN, AIN, TIN, Si₃N₄, SiC, B₄C, Ca(OH)₂, Mg(OH)₂, AI(OH)₃₎ Ca~ CO_3> MgC0₃, BaCO₃ and CaMg(CO₃)₂, or hydrates or mixtures thereof.

The glass material may be present in weight percentages of the total weight of the quenching material in a range between 5 to 45 wt%, or 15 to 35 wt%, or 20 to 35 wt%, or 25 to 35 wt%, or 5 to 30 wt%, or 10 to 30 wt%, or 15 to 30 wt%. The filler may be present in weight percentages of the total weight of the quenching materia! in a range between 5 to 45 wt%, or 5 to 40 wt%, or 5 to 30 wt%, or 0 to 25 wt%, or 5 to 25 wt%, or 0 to 15 wt%, or 0 to 10 wt%.

The quenching material may comprise any of the compounds or any combination of any of the compounds at any percentage and between any of the ranges mentioned in this application.

The quenching chamber 4 may comprise at least two opposite walls 5a, whereby, within one level a, one wail 5a comprises polyoxymethylene and optionally glass materials up to 35 wt% and/or mineral fillers up to 30 wt% and the opposite wall 5a comprises polymethylpentene and optionally glass materials up to 40 wt% and/or mineral fillers up to 50 wt%. In one embodiment the walls 5a comprise 0 to 40 wt%, or 10 to 35 wt%, or 25 to 35 wt% glass material and 5 to 50 wt%, or 0 to 30 wt%, or 0 to 20 wt%, or 0 to 10 wt% mineral fillers. The mineral filler may be selected from the group comprising CaO, MgO, ZnO, BaO, Zr0_{2 >} Ss0_{2 l} Ti0₂, ZrSi0₄, MgAI₂0₄, Al₂0₃, BN, ASM, CN, SiN, TIN, Si₃N_4j SiC, TiC, ZrC, WC, Mo₂C, VC, B₄C, WSs₂ and MoSi_2l TiB₂, ZrB_2> CaS0₄₎ gS0₄, AI₂(S0₄)₃, Ca(OH)₂, Mg(OH)₂₍ Zn(OH)₂, Ai(OH)₃₎ CaC0₃, NaHC0₃, KHC0₃, MgC0₃, BaC0_3l CaMg{C0₃}₂, K₂C0₃ and Na₂C0_3l or hydrates or mixtures thereof.

The quenching chamber 4 may comprise at least two opposite walls 5a, whereby, within one level a, one wall 5a comprises polyoxymethylene and optionally glass materials up to 35 wt% and/or mineral fillers up to 30 wt% and the opposite wall 5a comprises polyethylene, or polypropylene and optionally glass materials up to 40 wt% and/ or mineral fillers up to 50 wt%. In one embodiment the walls 5a comprise 0 to 40 wt%, or 10 to 35 wt%, or 25 to 35 wt% glass material and 5 to 50 wt%, or 0 to 30 wt%, or 0 to 20 wt%, or 0 to 10 wt% mineral fillers. The mineral filler may be selected from the group comprising CaO, gO, ZnG, BaO, Zr0₂, Si0₂, Ti0_{2 >} ZrSi0₄, gAI₂0₄, Ai₂0₃, BN, AIN, CN, SiN, TIN, Si₃N_4> SiC, TiC, ZrC, WC, o₂C, VC, B₄C, WSi₂ and oSi₂₎ TiB_{2 )} ZrB_{2 )} CaS0_4> MgS0_4> AI₂(S0₄)₃, Ca(OH)₂, g(OH)₂, Zn(OH)₂ and Ai(OH)₃, CaC0_3> NaHC0_3l KHC0_3l gC0_{3 )} BaC0_3> CaMg(C0₃)₂, K₂C0₃ and Na₂C0₃ or hydrates or mixtures thereof. In one embodiment the polyethylene is replaced by polypropylene. The quenching chamber 4 may comprise at least two opposite walls 5a, whereby, within one level a, one wall 5a comprises poiyoxymethyiene and optionally glass materials up to 35 wt% and/or mineral fillers up to 30 wt% and the opposite wall 5a comprises a polyamide and optionally glass materials up to 40 wt% and/ or mineral fillers up to 50 wt%. In one embodiment the polyamide is polyamide 6 or 6,6, 1 1 or 12. In another embodiment the poiyoxymethyiene is a copolymer. In one embodiment the walls 5a comprise 0 to 40 wt%, or 10 to 35 wt%, or 25 to 35 wt% glass material and 5 to 50 wt%, or 0 to 30 wt%, or 0 to 20 wt%, or 0 to 10 wt% mineral fillers. The mineral filler may be selected from the group comprising CaO, MgO, ZnO, BaO, Zr0₂, Si0_2l Ti0_{2 l} ZrSi0_4l gAI₂0₄, Al₂0₃, BN , AIN, CN, SiN, TIN, Si₃N₄, SiC, TiC, ZrC, WC, Mo₂C, VC, B₄C, WSi₂ and oSi₂, TiB₂, ZrB_{2 >} CaS0_{4 >} MgS0₄, AI₂(S0₄)₃, Ca(OH)_{2 l} Mg(OH)₂, Zn(OH)₂ and AI(OH)₃₎ CaC0₃, NaHC0₃, KHC0₃, MgC0₃, BaC0₃, CaMg(C0₃)₂, K₂C0₃ and Na₂C0₃ or hydrates or mixtures thereof.

The invention relates to use of a combination of quenching ma- teriais, whereby the quenching materials are selected from poiyoxymethyiene or copolymer thereof and optionally glass materials up to 35 wt% and/or mineral fillers up to 30 wt% combined with polymethyipentene, or polyethylene, or polypropylene, or polyamide 6, or polyamide 6,6, or polyamide 1 1 , or polyamide 12, and optionally glass materials up to 40 wt% and/or mineral fillers up to 50 wt%, for extinguishing or quenching an electrical arc between a fixed contact and a movable contact of a contact positioned in a quenching chamber. The percentages for the glass materials and mineral fillers may be replaced by any of the percentages or any of the ranges of percentages mentioned above.

The quenching chamber 4 as described above may be used in a method for extinguishing or quenching an electrical arc between a fixed contact and a movable contact of a contact positioned in a quenching chamber. Any combinations of any feature described above may be used in the chamber 4 and the method. The chamber 4 may further comprise a vent and the like to improve the quenching performance of the chamber 4. Experimentals

Experiments were performed in a RLC circuit under damped conditions using a capacitor bank. The experiments were performed in quenching chambers, whereby one wall 5a comprised polyoxymethylene (POM) and the opposite wall 5a comprised glass reinforced (25 wt%) polyamide 12 containing 5 wt% BN as a filler (PAGFBN). The experiment was repeated using POM or PAGFBN as quenching materia! on the walls 5a on both sides of the space 6.

The arc voltages for the different chambers are shown in Fig 7. The mean arc voltage of the combined asymmetric positioned material is clearly higher compared with the mean voltage from either of the materials. The capacitor bank was charged at d if- ferent voltage levels in order to simulate different operational conditions. The time at which the arc voltage starts to increase is an indication of the beginning of the pressure build up, and the moment that the material starts the ablation. Comparison of the times indicates that the chamber comprising the combination of the asymmetric positioned materials has a faster increase of the voltage (point F). The voltage remains higher in the new chamber 4 according to the invention as shown in points H. The results show that combining the materials in the chamber 4 allows controlling the time at which the gassing of the material takes place.

The effect of the same materials on gap conductance was measured in the capacitor bank. (Fig 8) These results show that the chamber 4 comprising the combination of the asymmetric positioned materials, has a lower gap conductance compared to the other two chambers (Point L in Fig 8). Also shown is that the gap conductance is lower during most of the breaking time.

The present invention is not limited to the embodiments disclosed but may be varied and modified within the scope of the following claims.

Claims

CLAI MS

1 . A quenching chamber (4) for a circuit interrupter (1 ) compris- ing a space (6), and at least two walls (5) at least partially enclosing the space (6) and positioned on opposite sides of the space (6), wherein the quenching chamber (4) is configured to comprise, in the space (6), a switch having a fixed contact (2) and a movable contact (3), between which contacts (2, 3) an arc can be generated, each wall (5) of the quenching chamber (4) comprises one or more levels (a) of wall units (9), whereby the wall unit (9) within one level (a) extend over a width (w) of the wall (5) along a first axis (x) and extend along a part or whole length (I) of the wall (5) along a second axis (y) being perpen- dicu!ar to the first axis, and whereby each wall unit (9) comprises quenching material, and

characterised in that

the wall units (9) on opposite sides of the space (6) within the same level (a) comprise quenching material having different quenching capabilities.

2. The quenching chamber (4) according to claim 1 , characterised in that the quenching material is selected from a first material having ablation capability at a start of a circuit interruption, a second material having cooling capabilities and a third material having neutralisation capabilities, or any mixtures thereof.

3. The quenching chamber (4) according to claim 2, characterised in that the first material ablates faster than the second and third material, and the second material cools the space (6) faster than the first and third material, and the third material neutralises faster than the first and second material.

A. The quenching chamber (4) according to any one of claims 1 to 3, characterised in that the at least two walls (5) comprise two levels (a, b) of wall units (9).

5. The quenching chamber (4) according to any one of claims 1 to 3, characterised in that the at least two walls (5) comprise three levels (a, b, c) of wall units (9), whereby the quenching materials comprised in the middle level (b) has different quenching capabilities from the quenching material comprised in at least one of the other levels (a, c) of wall units (9).

6. The quenching chamber (4) according to any one of claims 1 to 3, characterised in that at least three different walls (5) are present in the chamber (4), whereby, within one level (a), the quenching material comprised in the third wall may have the same or different quenching capabilities as the quenching material comprised in one or in both of the two opposite wall (5a).

7. The quenching chamber (4) according to any one of claims 1 to 6, characterised in that the first material is selected from the group comprising polyaceta!s, polyolefins, poiyamides and poly- acrylates, or copolymers or mixtures thereof, and optionally glass materials up to 35 wt% and/or mineral fillers up to 30 wt%.

8. The quenching chamber (4) according to any one of claims 1 to 6, characterised in that the second material is selected from the group comprising ceramic and thermosetting materials se- lected from the group comprising epoxy and polyesters, or copolymers or mixtures thereof, and optionally including glass materials up to 40 wt% and/ or mineral fillers up to 50 wt%.

9. The quenching chamber (4) according to any one of claims 1 to 6, characterised in that the third material is selected from the group comprising polyolefins, poiyamides, fluorinated polymers and thermosetting polymers, or copolymers or mixtures thereof, and optionally including glass materials up to 40 wt% and/or mineral fillers up to 50 wt%.

10. The quenching chamber (4) according to any one of ciaims 7 to 9, characterised in that the filler is selected from the group comprising

compounds of formula M_m(OH)_n, wherein M is a metal, m is 0, 1 , 2 or 3, and n is 0, 1 , 2, 3 or 4, and

compounds of formula Q_pH_yCO_{x >} wherein Q is selected from the group comprising Ca, Na, Mg, Ba and K and p is 0, 1 , 2 or 3, y is 0, 1 or 2 and x is 1 , 2 or 3, and

compound of formula T_tR_r, wherein T is selected from the group comprising Ca, Ai, Si, Zr, Ba, Ti, W, Mo, V, Mg, Zn and B, and

R is selected from the group comprising O, S0₄, C and N , wherein t is 1 , 2 or 3, and r is 0, 1 , 2, 3 or 4,

or hydrates or mixtures thereof,

1 1 , The quenching chamber (4) according to any one of claims 7 to 9, characterised in that the filler is selected from the group comprising CaO, MgO, ZnO, BaO, Zr0₂, Si0₂, Ti0_{2 )} ZrSi0₄, MgAi₂0₄, Ai₂0_{3 )} BN , A!N , CN , SiN , TiN , Si₃N_{4 >} SiC, TiC, ZrC, WC, Mo₂C, VC, B₄C, WSi₂ and MoSi₂, TiB₂, ZrB₂, CaS0₄, MgS0_{4 l} Ai₂(S0₄)₃, Ca(OH)_{2 f} Mg(OH)₂, Zn(OH)₂ and AI(OH)_{3 (} CaC0₃, NaHC0₃, KHC0₃, MgC0₃₍ BaC0_{3 )} CaMg(C0₃)₂, K₂C0₃ and Na₂C0_{3 l} or hydrates or mixtures thereof.

12. The quenching chamber (4) according to claim 1 , character- ised in comprising at least two opposite walls (5a) whereby, within one level (a), one wall (5a) comprises poiyoxymethylene and optionally glass materials up to 35 wt% and/or mineral filiers up to 30 wt% and the opposite wall (5a) comprises polymethylpentene or polyamide 6, 6,6, 1 1 or 12 and optionally glass materials up to 40 wt% and/or mineral fillers up to 50 wt%.

13. A switch comprising the quenching chamber (4) according to any one of claims 1 to 12.

14. A method for quenching an electrical arc between a fixed contact (2) and a movable contact (3) comprised in a switch, whereby the switch is positioned in a quenching chamber (4), comprising a space (6), and at least two walls (5) at least par- tialiy enclosing the space (6) and positioned on opposite sides of the space (6), and whereby the contacts (2, 3) are provided in the space (6) and between which an arc can be generated, and each wall (5) of the quenching chamber (4) comprises one or more levels (a) of wall units (9), whereby the wall unit (9) within one level (a) extend over a width (w) of the wall (5) along a first axis (x) and extend along a part or whole length (!) of the wall (5) along a second axis (y) being perpendicular to the first axis, and whereby each wall unit (9) comprises quenching material,

characterised I n that the wall units (9) on opposite sides of the space (6) within the same level (a) comprise quenching material having different quenching capabilities.

15. The method according to claim 14, characterised in that the quenching material comprises quenching capabilities selected from a first material having ablation capability at a start of a circuit interruption, a second material having cooling capabilities and a third material having neutralisation capabiliiies, or any mixtures thereof.