Patent Application
20160329177
The invention relates to an arc chamber to extinguish electric arcs for a contactor with an extinguishing system, a blowing device which blows electric arcs into the extinguishing system, and a plurality of lamellar electric arc extinguishing elements between which flow channels are formed, wherein the flow channels each comprise a scattering section.
Contactors with such arc chambers are used for example in railway operations to switch loads and to interrupt electric circuits with large currents and high voltages. In the switching process, i.e. during opening of contact areas, an electric arc is formed at the contact areas. The current flow between contacts is maintained due to this electric arc. In addition, a large amount of heat is released by this electric arc, whereby the contacts are burnt down which can lead to a reduced lifespan of the contactor. Furthermore, the entire device area that is influenced by the effect of the electric arc is exposed to a very strong thermal stress. Therefore, an arc chamber is used which leads to a fast breakdown of the electric arc.
Especially for AC and DC operation, the accumulation of electrically conductive plasma in the extinguishing system, which leads to an unfavorable switching behavior of the contactor, should be avoided. Consequently, the plasma is blown with the electric arcs by the blowing device in the direction of the extinguishing unit and the plasma is released to the environment via flow channels.
An extinguishing chamber of the generic kind is for instance known from WO 93/13538 A1.
In the known arc chamber, the flow channels are formed identically and in parallel to each other so that the outflowing plasma accumulates in the area at the output apertures of the flow channels so that it can lead to thermal stress of the arc chamber and, if appropriate, entail the risk of an electric arc escaping from the arc chamber.
Hence, it is an objective of the present invention to provide an arc chamber for a contactor, which has a long lifespan and which ensures increased safety.
According to the invention, the scattering sections of adjacent flow channels are formed with different inclinations so that the emerging plasma is deflected in different directions by the flow channels. Especially the average temperature at the ends of the flow channels that face away from the contact area is significantly reduced so that a plasma concentration is prevented and the thermal stress is reduced.
The extinguishing system can in particular comprise one or several electric arc guiding plates that guide the electric arc from contact areas into the extinguishing system on opening of the contactor. Preferably, two electric arc guiding plates, which form a V-shape, are arranged. Preferably, at least one contact area with a fixed contact is arranged in the arc chamber. The blowing device preferably creates a magnetic blowout field that blows electric arcs into the extinguishing system. This is preferably achieved by the blowing device having at least one permanent magnet arranged adjacent to the contact areato create a permanent magnetic blowout field, and/or having at least one coil arranged adjacent to the contact area to create an electromagnetic blowout field. The blowout field can further be amplified by magnetically conductive pole plates that are preferably arranged in pairs parallel to each other with an intermediate arrangement of the extinguishing system. Preferably the contact area is also arranged between the pole plates so that a substantially homogeneous magnetic blowout field is formed in the area around the contact area, i.e. the switching area. The fixed contact and/or the electric arc guiding plate are preferably arranged in a way that emerging electric arcs are aligned substantially perpendicular to the magnetic blowout field so that the acting Lorenz force is maximized. Preferably, the flow channels are aligned substantially in the blowing direction so that the emerging plasma can be blown into the flow channels with a low resistance.
Moreover, the arc chamber can be both integrated in the contactor as one part or be formed as a removable part of the contactor.
According to a second aspect of the present invention, the flow channels extend in opposite directions. Thereby, several scattering sections extend preferably with an inclination angle in relation to the blowing direction while other scattering sections extend in an inclined way by the same angle but in an opposite direction and on the same plane in relation to the blowing direction. This arrangement is particularly advantageous when several elongated arc chambers are arranged next to each other, wherein the plasma exits the respective arc chambers in their transversal direction. As several arc chambers are arranged next to each other and hence several contactors are usually not opened simultaneously, the space above the scattering sections of different arc chambers is optimally used for cooling.
According to a third aspect of the present invention, the extinguishing system includes several electric arc extinguishing elements that are arranged next to each other so that at least one flow channel is formed between two adjacent electric arc extinguishing elements. Preferably a respective flow channel is formed between all adjacent electric arc extinguishing elements. The electric arc extinguishing elements can be made preferably of ceramics so that one of their ends can respectively be exposed towards the outside. Hence, the electric arc extinguishing elements do not have to be protected by an additional electrically insulating cover towards the outside so that the cooling of the electric arc extinguishing elements is further improved. The flow channels can, but do not have to, comprise respectively one extinguishing section which is formed in an upstream position in relation to the blowing direction and which forms a part of the extinguishing system.
According to a fourth aspect of the present invention and for the purpose of cost savings, the electric arc extinguishing elements are formed identically, wherein respectively two consecutive electric arc extinguishing elements are arranged in a way as to be turned towards each other by 180 degrees, wherein the electric arc extinguishing elements each include at least one first air-deflecting recess at a first side area and at least one second air-deflecting recess at a second side area that is located opposite to the first side area.
Thereby, the first and the second recesses are inclined relative to the blowing direction and aligned relative to each other so that the first recesses respectively form a scattering section with the adjacent second recesses, wherein each of the scattering sections deflects the air differently.
According to a fifth aspect of the present invention, the flow channels each have a change in cross-section that separates the extinguishing section from the scattering section. This prevents the plasma from leaving the arc chamber with a too high speed without being cooled down by the scattering section.
According to an ancillary aspect, the invention further relates to an arc chamber for a contactor, wherein the arc chamber comprises at least one contact area with a fixed contact, at least one extinguishing system and a blowing device to create a magnetic blowout field which blows electric arcs into the extinguishing system, wherein the blowing device includes at least one permanent magnet, which is arranged adjacent to the contact area, to create a permanent magnetic blowout filed and/or at least one coil, which is arranged adjacent to the contact area, to create an electromagnetic blowout filed so that an electric arc, that emerges on opening of the contact area, is blown into the at least one extinguishing system, wherein at least two magnetically conductive pole plates are arranged in parallel to each other with intermediate arrangement of the permanent magnet and/or the coil so that the blowing effect is achieved by magnetic fields for guiding the electric arcs in the area that is provided for this purpose.
Such an arc chamber is known from the state of the art, for example from the EP 2 230 678 A2. An arc chamber contains wear parts that must be frequently checked and, if necessary, replaced. Further, such an arc chamber with a permanent magnet and/or a coil is very heavy and therefore needs to be firmly connected to a base part in a mechanical way.
Therefore, an objective of the present invention is to provide an arc chamber which can be easily removed and at the same time fastened well to the base part of a contactor.
The problem is solved by at least one of the pole plates being formed as a swivelable locking system by means of which the arc chamber is removable from a base part of a contactor in an unlocked state and connectable to the base part of the contactor in a form-locking way in a locked state. Preferably, the swivelable pole plate includes a hook or a protrusion on the side that faces the base part while the base part respectively includes a corresponding bolt or a recess. In particular, the arc chamber can include an insulating enclosure wherein the pole plate is arranged outside of the enclosure so that the pole plate is coupled magnetically but not electrically with the energized parts in the enclosure. Due to the size and the stability of the pole plates, the strength of the locking system is ensured without any additional parts.
According to a seventh aspect of the present invention, a locking lever is eccentrically swivelable connected to the swivelable pole plate and supported by a holder in a way that a swivel movement of the pole plate leads to a translational movement of the locking lever. The swivel axis of the pole plate thereby is spaced apart from the swivel axis of the locking lever and hence provided eccentrically.
According to an eighth aspect of the present invention, the locking lever is swivelable connected to the pole plate at an end and supported on the opposite, free end by the holder, which comprises a movable safety locking device that in the locked state of the pole plate is pressed into a locked position over the free end by a spring element so that the translational movement of the locking lever and hence also the swivel movement of the pole plate is prevented by the safety locking device. The holder can preferably be formed at one half of the enclosure and be formed in one piece with the latter. The free end is preferably the one end that faces away from the blowing device so that the movable safety locking device is easily accessible from the side of the arc chamber that faces away from the base part.
According to a ninth aspect of the present invention, a display element arranged on the locking lever is visible in the unlocked state and not visible in the locked state. Preferably, the free end of the locking lever is correspondingly marked in color and covered in a locked state, due to the movable safety locking device, and hence not visible.
According to a tenth aspect of the present invention, the swivel movement of the swivelable pole plate is limited in both directions by a respective stop surface. This ensures that the swivelable pole plate will not come in undesired contact with other parts during assembly or an inspection.
According to an eleventh aspect of the present invention, the blowing device comprises at least one coil with a swivelable first pole plate as well as at least one permanent magnet with a non-rotatable second pole plate wherein the first and the second pole plate are separated from each other by an intermediate gap and mounted in one plane. Preferably, the pole plates are correspondingly arranged in pairs and in a way that the coil is arranged between two swivelable pole plates and that the permanent magnet is arranged between two non-rotatable pole plates.
According to a twelfth aspect of the present invention, a stop surface is formed by the enclosure of the arc chamber.
According to another ancillary aspect of the present invention, the invention further relates to an arc chamber for a contactor which comprises at least one contact area with a fixed contact, an extinguishing system and a blowing device that blows electric arcs into the extinguishing system.
At the time of filing, skilled persons have the prejudice that mechanical contactors, in contrast to semiconductor contactors, would not need a heat-dissipating cooling element. The thermal situation of mechanical contactors is usually kept at a certain level by indicating, for example, low power limits or by overdimensioning contact plates. The inventors, however, have surprisingly found that a higher effective power of a conductor can be achieved without much effort by installing a cooling element, which is connected to the fixed contact in a thermally conductive way, on the arc chamber that has been known so far. The fixed contact is particularly plate-shaped and hence has a large contact surface in the switching area close to the contact area. Consequently, cooling of the switching area can be achieved by the cooling element with particular efficiency.
According to a fourteenth aspect of the present invention, the arc chamber further includes an electrically insulating enclosure, wherein the fixed contact extends through the enclosure and consequently forms an electric contact at which the cooling element is mounted.
According to another ancillary aspect of the present invention, the invention further relates to an arc chamber for a contactor comprising at least one contact area with a fixed contact, an extinguishing system with an electric arc guiding plate, wherein an air gap is provided in the proximity of the contact area between the electric arc guiding plate and the fixed contact, and a blowing device to create a magnetic blowout filed which blows electric arcs into the extinguishing system wherein the blowing device comprises at least one permanent magnet, which is arranged adjacent to the contact area, to create a permanent magnetic blowout filed and/or at least one coil, which is arranged adjacent to the contact area, to create an electromagnetic blowout field, so that an electric arc that emerges on opening of the contact area is blown into the at least one extinguishing system wherein a protective cladding is arranged between the air gap and the permanent magnet and/or the coil and extends from the fixed contact towards the electric arc guiding plate.
Such an arc chamber is known for example from the EP 2 230 678 A2 which discloses a protective cladding that is glued to the enclosure.
Therefore, an objective of the present invention is also to provide an arc chamber, wherein the protective cladding is safely fastened and easily replaceable.
The problem is solved by the protective cladding being insertable in the direction of the extinguishing system and hence replacably arranged. In particular, the protective cladding should preferably be insertable under the electric arc conductor piece from below and in the direction of the extinguishing system.
According to a sixteenth aspect of the present invention, the protective cladding is fastened by means of a groove or a protrusion, wherein such groove or protrusion extends perpendicularly to the surfaces of the fixed contact. The arc chamber can further include an enclosure which includes internal delimitation walls, which are provided perpendicularly to the side walls of the enclosure, for receiving the permanent magnet or the coil. Preferably, the protective cladding is attached to such internal delimitation walls through the groove or the protrusion and limited in the direction of the magnetic blowout filed or in the direction of the central axis of the coil or of the north-south direction of the permanent magnet by the side walls of the enclosure.
Preferably, ceramics, e.g. steatite or cordierite, will be used as a material for the protective cladding and/or the electric arc extinguishing elements to enable a simple design and good protection against damages caused bye electric arcs.
According to another ancillary aspect of the present invention, the invention also relates to a contactor for a direct current and/or alternating current operation with at least one movable contact wherein the contactor further includes an arc chamber according to one of the abovementioned aspects.
According to an eighteenth aspect of the present invention, the contactor includes a base part with a locking mechanism which interacts with the swivelable pole plate so that the arc chamber is lockable and unlockable with the base part.
Different design variants can be combined with each other completely or in relation to other characteristics; a design variant can also be complemented by other described characteristics.
In the following, the invention will be explained in greater detail by means of the drawings. The drawings show:
On the upper side that faces away from the base part 3, also a holder 19a is formed that extends through the enclosure 15 of the arc chamber 7, wherein two locking levers 17a, b are supported by the holder 19a between a semicircular support plate 21a and the enclosure 15 in a way that a translational movement of the locking levers 17a, b alongside their longitudinal axis is enabled. On the ends that face away from the holder 19a, the locking levers 17a, b are each swivelable supported around a swivel axis 18a, b on the respective swivelable pole plates 11a, 11b. The swivel axes 18a, b of the locking levers 17a, b are arranged in the proximity of the central axis 8 while the swivel axes 12a, b of the swivelalbe pole plates 11a, b are respectively arranged spaced apart from the central axis 8. Each swivelable pole plate 11a, b has a laterally extending operating lever 23a, b which is provided above the respective electric contact 9a, b so that the swivelalbe pole plates 11a, b can be operated more easily by the operating levers 23a, b. Hence, swivel movements of the left swivelalbe pole plate 11a in clockwise direction or the right swivelable pole plate 11b in a counter-clockwise direction are limited. In the respective opposite direction, the swivel movement comes to a halt on the enclosure due to second stop surfaces 31a, b (see
The cooling elements 37a, b have each a series of cooling ribs 39 that are arranged alongside the circumferential direction of the cooling elements 37a, b. A bolt formed as an electric contact is respectively received in a central borehole of the cooling elements 37a, b so that the plane of the contacts is elevated by the thickness of the cooling elements 37a, b. On the not depicted underside of the cooling elements 37a, b, the bolts formed as electric contacts 9a, b are respectively attached to a contact plate that is formed as a fixed contact and that extends through the enclosure 15. The electric contacts 9a, b as well as the fixed contacts are cooled efficiently by the cooling elements 37a, b.
On the upper side of the enclosure 15 that faces away from the base part, an elongated, square-shaped free surface is provided so that the lamellar electric arc extinguishing elements 41 are exposed at the top. Several outlet apertures 43 of flow channels, which are formed respectively between two adjacent electric arc extinguishing elements 41, are displayed.
The enclosure 15 consists of two enclosure halves 15a, b that are connected to each other through connector bolts 45 with respectively one internal borehole. On the top side of the enclosure 15, two holders 19a, b with respectively one support plate 21a, b, which are explained in greater detail with reference to
As shown in
An electric arc guiding plate 59, 60 is arranged adjacent to the fixed contacts 54, 55 at each contact area 52, 53, wherein the electric arc guiding plates 59, 60 are insulated from the respective fixed contact 54, 55 by a respective air gap 61, 62. The electric arc guiding plates 59, 60 are shaped in a way as to form an electric arc conductor pit 69 between the contact areas 52, 53 which is substantially perpendicular to the longitudinal extension of the contact bridge 58 and through which the electric arcs 65 or 66 (depending on the movement direction of the electric arc) are blown in the direction of an extinguishing unit 74 by means of the blowout fields of the permanent magnets 63, 64 and/or blowing coils 67, 68.
The blowing coils 67, 68 are arranged substantially between the swivelable pole plates 11a, b, while the permanent magnets 63, 64 are arranged substantially between the fixed pole plates 13a, 13b. The pole plates 11a, b, 13a, b are not displayed in
On each of the two contact areas 52, 53, a protective cladding 75, 76 is arranged next to the air gap 61, 62. The protective claddings 75, 76 are arranged respectively between the air gap 61, 62, the permanent magnets 63, 64, the fixed contacts 54, 55 and the electric arc guiding plates 59, 60 and extend from the respective fixed contacts 54, 55 upwards to the respective electric arc guiding plates 59, 60. Therefore, a closed space is formed by the protective claddings 75, 76, the fixed contacts 54, 55 and the respective electric arc guiding plates 59, 60 so that the permanent magnets 63, 64 and the blowing coils 67, 68 are protected against electric arcs and the emerging plasma when electric arcs 65, 66 enter the closed space on activation of the blowing coils 67, 68. To fasten the protective claddings 75, 76, it is provided that each of the two cylindrical slots 77, 78 for the permanent magnets 63, 64 that extend through the enclosure are supposed to have a protrusion which extends in the direction of the magnetic blowout filed or the north-south direction of the permanent magnets 63, 64. The protective claddings 75, 76 each have a groove 79 through which the protective claddings 75, 76 are retained in the slots 77, 78. Hence, the protective claddings 75, 76 are also insertable in the direction of the extinguishing system and replacably arranged.
The protective claddings 75, 76 are made of a material that is resistant to electric arcs. Preferably, a ceramic material, especially steatite or cordierite is used for this purpose. These materials have a certain porosity so that they are relatively stable even in case of temperature shocks. This is necessary especially because the electric arc temperature has values up to 20000 K.
A plurality of electric arc extinguishing elements 41 is arranged in a lamellar shape in the extinguishing system 74 above the electric arc guiding plates 59, 60. Between the electric arc extinguishing elements 41, flow channels are formed which need to be further explained and which extend from the electric arc guiding plates 59, 60 in a substantially vertical upward direction. Hence, the air and possibly the plasma, which emerge between the contacts 54, 55, 56, 57 as well as between the electric arc guiding plates 59, 60, are blown into the flow channels and therefore are cooled by the electric arc extinguishing elements 41.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20 2014 002 902.6 | Feb 2014 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/001554 | 6/6/2014 | WO | 00 |
