CONTACTORS WITH ARC GUIDES AND INTEGRATED PROTECTION FOR ARC GUIDES, SYSTEM AND CORRESPONDING AIRCRAFT

Description

Technical Field

[0001] The invention relates to the general field of electrical power distribution, in particular within aircraft. It relates in particular to contactors used in aircraft electrical power distribution systems. Prior art

[0002] An aircraft uses an HVDC (High Voltage Direct Current) electrical power distribution system. Electrical loads are not usually supplied directly by electrical sources, as contactors are used to control this power supply or to switch the power within the distribution system.

[0003] A typical setup consists of the HVDC source, a distribution box, cables for connecting the source to the distribution box, and an electrical load connected to the distribution box. In the distribution box, on each phase, a contactor is arranged in series to interface between the electrical source and the electrical load(s).

[0004] It is recalled that a contactor generally comprises two electrical contacts and a movable bridge which can be moved between a so-called closed position in which the movable bridge is in contact with the first electrical contact and the second electrical contact, and a so-called open position in which the movable bridge is spaced from the first electrical contact and the second electrical contact.

[0005] From the state of the prior art, contactors described in documents EP 1388154 and EP 2278599 are known.

[0006] Document EP 2463876 A1 describes a contactor according to the preamble of claim 1.

[0007] As we will see with reference to the figures 1 à 5 , when the mobile bridge is opened, electric arcs appear.

[0008] There figure 1 is a schematic sectional view of a contactor 10 according to the prior art. This contactor comprises a first electrical contact 11A, a second electrical contact 11B, and a movable bridge 12.

[0009] In the figure, the movable bridge 12 is in the closed position. Its lower face F1 is in contact with the two electrical contacts 11A and 11B, at the contact interfaces IC. As a result, current can flow through the contactor from the first contact 11A to the second contact 11B through the movable bridge 12. The flow of current is represented by thick line arrows in the figure.

[0010] It may be noted that the contactor further comprises a lower arc guide, comprising a first portion 13A connected to the first electrical contact 11A, which extends in the opposite direction to the second electrical contact relative to the first electrical contact. The lower arc guide further comprises a second portion 13B connected to the second electrical contact 11B, which extends in the opposite direction to the first electrical contact relative to the second electrical contact. The lower arc guide extends in the lower portion of the contactor, delimited by the movable bridge (in the figure, below the movable bridge, there is the lower portion, and above the movable bridge, there is the upper portion).

[0011] On the side of the upper face F2 of the movable bridge, which is opposite to the face F1, in the upper portion of the contactor, an upper arc guide 14 is arranged.

[0012] At the lateral ends of the contactor, between the upper arc guide and the lower arc guide, arc breaking fins 15 are arranged.

[0013] The lower arc guide and the upper arc guide have a shape configured so that the space between these arc guides increases when moving away from the electrical contacts (for example this space increases from the first electrical contact 11A in the direction opposite to the second electrical contact 11B, and this space increases from the second electrical contact 11B in the direction opposite to the first electrical contact 11A).

[0014] Additionally, although not shown in the figure, the contactor has permanent magnets generating a magnetic field B , the direction of which falls within the plane of the figure is symbolized by a cross in a circle.

[0015] We will now describe the appearance of electric arcs and the operation of the arc guides of the contactor according to the prior art described with reference to the figure 1 .

[0016] On the figure 2 , the separation of the contacts between the movable bridge 12 and the first electrical contact 11A on the one hand, and the movable bridge 12 and the second electrical contact 11B on the other hand, is shown. At the open interface IO between the movable bridge and the first electrical contact 11A, a first electric arc AA, and, simultaneously, at the open interface IO between the movable bridge and the second electrical contact 11B, a second electric arc AB are formed. The two electric arcs AA and AB are formed by ionization of the air at the open interfaces IO. Thus, a current continues to flow through the contactor.

[0017] On the figure 2 , an enlargement of the interface between the upper arc guide 14 and the movable bridge 12 has also been shown. These two elements are not intended to be in contact in the so-called open position.

[0018] There figure 3 watch, shortly after the opening shown on the figure 2 , the displacement on either side of the movable bridge of arcs AA and AB. More precisely, arc AA moves to the left side in the figure, and arc AB moves to the right side in the figure. These two displacements result from the presence of the magnetic field B and its effect on the Laplace force (designated F Laplace (in the figure). As can be seen in the figure, the shape of the arc guides makes the electric arcs AA and AB longer, which can help them to be cut.

[0019] On the figure 4 , the electric arcs are shown continuing to move to the sides, shortly after their movement shown on the figure 3 . In this figure, we can observe the deformation of the arcs which come to lick the arc guides. Also, at this stage, the current still flows in the movable bridge.

[0020] Subsequently and as shown in the figure 5 , the current ceases to follow the path passing through the electric arcs licking the arc guides and the bridge, in the upper portion, to pass entirely into the upper arc guide 14. In the lower portion, the current passes partly through the two lower arc guide portions 13A and 13B.

[0021] AA and AB arcs can continue indefinitely, but we generally want to break them within 3 milliseconds. In fact, arcing beyond 30 milliseconds can damage the inside of the contactor.

[0022] If the current flowing through the contactor is too high, the fins 15 may not be suitable for cutting the arcs AA and AB, which will stagnate in or in front of these fins.

[0023] It should be remembered that these electric arcs are plasmas of several thousand degrees, which, if maintained for too long, can damage the contactor or even spread beyond the contactor.

[0024] There is therefore a need for a solution that prevents this damage.

[0025] Since arcs are particularly problematic for high currents, fuses can be used in series with the contactors designed to melt when these high currents appear (typically when a short circuit occurs).

[0026] For this purpose, we know the fuses used in HVDC systems in the automotive sector, or the devices called pyrofuse.

[0027] While adding a fuse or pyrofuse in series with the contactor could work, this solution has the disadvantage of requiring bulky, heavy, and difficult to integrate components around the contactors.

[0028] The invention aims in particular to overcome these drawbacks. Statement of the invention

[0029] To this end, the invention proposes a contactor intended to be used in an electrical power distribution system within an aircraft and comprising a first electrical contact, a second electrical contact, and a movable bridge movable between a so-called closed position in which the movable bridge is in contact with the first electrical contact and the second electrical contact, and a so-called open position in which the movable bridge is spaced from the first electrical contact and the second electrical contact, the movable bridge having a first face intended to be in contact with the first electrical contact and the second electrical contact in the closed position, and a second face opposite the first face, the contactor further comprising: a lower arc guide comprising a first portion connected to the first electrical contact, extending in the opposite direction to the second electrical contact with respect to the first electrical contact, and a second portion connected to the second electrical contact, extending in the opposite direction to the first electrical contact with respect to the second electrical contact, an upper arc guide located on the side of the second face of the movable bridge and comprising a first portion facing the first portion of the lower arc guide, a second portion facing the second portion of the lower arc guide, and a fuse connecting the first portion and the second portion of the upper arc guide.

[0030] By facing, we mean that an electric arc can be formed between these two portions, even if they are inclined relative to each other.

[0031] Thus, the invention proposes to use a fuse directly in the contactor, to cut the current flow when the current passes at the upper arc guide. In this case, which appears after opening of the movable bridge, for a given duration and a given current (i.e. I 2 < t greater than a nominal use of the fuse), the fuse will melt and cut the arc.

[0032] The fuse dimensions can be chosen according to the application and in particular according to the duration for which one accepts to see electric arcs maintained for a given current. In particular, one can use a smaller fuse than if one places a fuse in series with the contactor (or a pyrofuse), because no current passes through the fuse referred to here when the contactor is in the closed position. This provides protection against the maintenance of electric arcs, with a low impact on the total mass and on the size.

[0033] The upper arc guide therefore comprises two separate parts connected through the fuse.

[0034] As an indication, it is observed that the use of an upper arc guide and a lower arc guide can allow, by the configuration of the arc guides, to move the electric arcs from the contact zone to the breaking zone by lengthening the arc before the latter reaches, for example, fins if they are present. The elongation of the arc can be a first step in breaking in that it gradually reduces the current. For example, the use of an upper arc guide and a lower arc guide allows better control of the movement of the arc.

[0035] According to a particular embodiment, the upper arc guide comprises a plurality of fuses electrically connected between the first portion and the second portion of the upper arc guide.

[0036] Therefore, a circuit with multiple fuses, or a single fuse, can be used. If multiple fuses are used, they can be connected in series and / or in parallel between the two arc guide sections.

[0037] According to a particular embodiment, the upper arc guide comprises a fuse holder for connectingly receiving said fuse, or several holders for receiving each fuse of the plurality of fuses if the upper arc guide comprises a plurality of fuses.

[0038] The fuse can therefore be a discrete component, which is connected to a fuse holder.

[0039] According to a particular embodiment, the contactor is configured to receive a continuous nominal current of intensity I, and in which the fuse / the plurality of fuses is configured to melt upon receiving a current greater than 10 times I for a duration greater than 50 ms, or for a duration greater than 10 ms.

[0040] Typically, for I equal to 400A, the fuse can be configured to melt upon receiving a current greater than 4000A for a duration greater than 50ms, or even for a duration greater than 10ms.

[0041] According to a particular embodiment, the fuse / plurality of fuses is configured not to melt when receiving a current of the order of I for a duration less than or equal to 10 ms.

[0042] A current of the order of I will for example be included in a range of plus or minus 10% around the value of I.

[0043] In fact, the upper arc guide will be passing currents resulting from arcs that themselves result from the passage of the rated current. This does not require having a fuse that blows at this point.

[0044] With this embodiment, it is possible to use fuses that are small in size and low in weight.

[0045] It should be noted that if a fuse were used in series with the contactor, this fuse could, for example, have to accept a current of 400A permanently, and this fuse would be much larger than the fuse used here which is only crossed by a current when arcs appear for a duration of, for example, less than 10 milliseconds and for a current of 400A.

[0046] In fact, a fuse capable of permanently accepting 400A can accept, for example, 500A for 10 seconds, or 5000A for 0.1 seconds (we have (500A) 2< x10s=(5000A) 2< x0.1s).

[0047] .

[0048] If we use a fuse that can accept 400A for 10ms and for example a steady state reached at 1000s, we have: (400A) 2 < * 0.01s = (12.7A) 2 < * 1000s. In other words, the fuse that can accept 400A for 10ms can accept 12.7A permanently. But, since a 400A, 1000V fuse has dimensions of approximately 135mm * 52mm * 73mm for 500 grams, and a 10A, 1000V fuse is 38mm long and 10mm in diameter for 10 grams, the 10A fuse (approximately) will be much less bulky and heavy.

[0049] The invention also provides an electrical energy distribution system comprising a high voltage direct current source (for example which delivers a nominal continuous current of intensity I), a contactor as defined above having a first electrical contact connected to the high voltage direct current source and a second electrical contact connected to a terminal of the system for connecting a load.

[0050] The invention also proposes an aircraft comprising an electrical energy distribution system as defined above. Brief description of the drawings

[0051] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate an exemplary embodiment thereof without any limiting character. In the figures: [ Fig. 1 ] There figure 1 , already described, schematically illustrates a contactor according to the prior art in the closed position. Fig. 2 ] There figure 2 , already described, schematically illustrates the contactor of the figure 1 in open position. [ Fig. 3 ] There figure 3 , already described, shows the movement of the electric arcs after the opening visible on the figure 2 . [ Fig. 4 ] There figure 4 , already described, shows the displacement of the electric arcs after the first displacement visible on the figure 3 . [ Fig. 5 ] There figure 5 , already described, shows the passage of current through the upper arc guide. [ Fig. 6 ] There figure 6 shows a contactor according to one embodiment. Fig. 7 ] There figure 7 is a graph that shows the melting of the fuses used in the contactor of the figure 6 . [ Fig. 8 ] There figure 8 shows an electrical distribution system according to one embodiment, included in an aircraft. Description of the embodiments

[0052] We will now describe a contactor equipped with a fuse, according to one embodiment.

[0053] There figure 6 is a schematic sectional view of a contactor. This contactor comprises a first electrical contact 110A, a second electrical contact 110B, and a movable bridge 120.

[0054] In the figure, the movable bridge 120 is in the open position. Its lower face F10 is spaced from the two electrical contacts 110A and 110B, at the open interfaces IO. As a result, current can only flow through the contactor from the first contact 110A to the second contact 110B via electrical arcs described below. The flow of current is represented by thick line arrows in the figure.

[0055] The contactor further comprises a lower arc guide, comprising a first portion 130A connected to the first electrical contact 110A, which extends in the opposite direction to the second electrical contact with respect to the first electrical contact. The lower arc guide further comprises a second portion 130B connected to the second electrical contact 110B, which extends in the opposite direction to the first electrical contact with respect to the second electrical contact. The lower arc guide extends in the lower portion of the contactor, delimited by the movable bridge (as visible in the figure, below the movable bridge, the lower portion is seen, and above the movable bridge, the upper portion is seen).

[0056] On the side of the upper face F20 of the movable bridge, which is opposite the face F10, in the upper portion of the contactor, an upper arc guide is arranged. This upper arc guide comprises a first portion 140A which faces the first portion of the lower arc guide 130A, by facing, it is meant that an electric arc can be formed between these two arc guides, although they are inclined relative to each other. The upper arc guide comprises a second portion 140B which faces the second portion 130B of the lower arc guide.

[0057] The first portion 140A further comprises a sub-portion 141A parallel and facing the upper face F20 (it is spaced from this face), and the second portion 140B further comprises a sub-portion 141B parallel and facing the upper face F20 (it is also spaced from this face).

[0058] The connection between the two portions 140A and 140B of the upper arc guide is made by means of a fuse 160. This fuse is connected to the portions 140A and 140B through a two-part fuse holder, a portion 142A connected to the sub-portion 141A, and a portion 142B connected to the sub-portion 141B.

[0059] At its lateral ends, between the upper arc guide and the lower arc guide, arc cut-off fins 150 are arranged.

[0060] The lower arc guide and the upper arc guide have a shape configured so that the space between these arc guides increases with distance from the electrical contacts (for example this space increases from the first electrical contact 110A in the direction opposite to the second electrical contact 110B, and this space increases from the second electrical contact 110B in the direction opposite to the first electrical contact 110A).

[0061] Additionally, although not shown in the figure, the contactor has permanent magnets generating a magnetic field B , whose direction entering the plane of the figure is symbolized by a cross in a circle. This magnetic field B causes the electric arcs to move towards the sides of the contactor, by means of the Laplace force (designated F Laplace in the figure).

[0062] In the figure, the contactor is shown in the open position, with an electric arc AA formed between the first portion 130A of the lower arc guide and the first portion 140A of the upper arc guide, and an electric arc AB formed between the second portion 130B of the lower arc guide and the second portion 140B of the upper arc guide.

[0063] Both arcs have an existence that has been long enough for current to flow through the upper arc guide, as shown in the figure.

[0064] And, as illustrated, the current, to pass from the first portion 140A of the arc guide to the second portion 140B of the arc guide, must pass through the fuse 160.

[0065] The fuse can be sized so that the fuse blows after a given time, and for a given current.

[0066] For example, for a contactor configured to receive a continuous nominal current of intensity I (for example 400A), the fuse is configured to melt upon receiving a current greater than 10 times I for a duration greater than 50 ms, or for a duration greater than 10 ms, depending on the application.

[0067] Also, the fuse can be configured to not melt when receiving a current of the order of I for a duration less than or equal to 10 ms.

[0068] The person skilled in the art will be able to size the fuse to verify these conditions.

[0069] There figure 7 is a graph that shows the fusion curves (called I 2 < t curves) of two fuses that can be used to protect a contactor.

[0070] More precisely, curve C1 shows the melting curve I 2< t of a fuse such as fuse 160 usable in contactor 100 described with reference to the figure 6 , capable of withstanding the passage of a current of 400A for a duration slightly greater than 10 milliseconds without melting, but not beyond.

[0071] On the other hand, if we had to use a fuse in series with the contactor to avoid current peaks that appear when a short circuit occurs, we would use a fuse in accordance with curve C2, always above the nominal 400A, because this current always flows through it since it is in series with the contactor. A fuse in accordance with curve C2 is larger and heavier than a fuse in accordance with curve C1 that can be used in the contactor according to the invention.

[0072] On the figure 8 , an electrical energy distribution system 2000 is schematically represented comprising a high voltage direct current source 200, a distribution box 300, and cables 400 which connect the source 200 to the distribution box 300.

[0073] In the distribution box 300, for each phase, there is a contactor and here, the two contactors are in a contactor box 1000. The contactors can be those described with reference to the figure 6 .

[0074] The contactor is connected by 500 bus bars to 600 outputs for connecting an electrical load.

[0075] The figure partially shows an aircraft 3000 in which the system 2000 is used.

[0076] The embodiments described above make it possible to protect the contactors used in aircraft, with an impact on the weight and mass of the aircraft which is limited compared to other solutions in which a fuse could be placed in series with a contactor.

Claims

1. A contactor intended to be used in an electrical power distribution system (2000) within an aircraft (3000) and including a first electrical contact (110A), a second electrical contact (110B), and a movable bridge (120) movable between a so-called closed position in which the movable bridge is in contact with the first electrical contact and the second electrical contact, and a so-called open position in which the movable bridge is spaced apart from the first electrical contact and the second electrical contact, the movable bridge having a first face (F10) intended to be in contact with the first electrical contact and the second electrical contact in the closed position, and a second face (F20) opposite the first face, the contactor further including: - a lower arc guide comprising a first portion (130A) connected to the first electrical contact, extending in the direction opposite the second electrical contact with respect to the first electrical contact, and a second portion (130B) connected to the second electrical contact, extending in the direction opposite the first electrical contact with respect to the second electrical contact, - an upper arc guide located on the side of the second face of the movable bridge and comprising a first portion (140A) facing the first portion of the lower arc guide, a second portion (140B) facing the second portion of the lower arc guide, and characterized by a fuse (160) connecting the first portion and the second portion of the upper arc guide.

2. The contactor according to claim 1, wherein the upper arc guide comprises a plurality of fuses electrically connected between the first portion and the second portion of the upper arc guide.

3. The contactor according to claim 1 or 2, wherein the upper arc guide comprises a fuse holder (142A, 142B) for connecting said fuse, or a plurality of holders for each fuse of the plurality of fuses if the upper arc guide comprises a plurality of fuses.

4. The contactor according to any one of claims 1 to 3, wherein the contactor is configured to receive a continuous nominal current of intensity I, and wherein the fuse / the plurality of fuses is configured to melt on receiving a current greater than 10 times I for a duration greater than 50 ms, or for a duration greater than 10 ms.

5. The contactor according to claim 4, wherein the fuse / the plurality of fuses is configured not to melt on receiving a current of the order of I for a duration less than or equal to 10 ms.

6. An electrical power distribution system comprising a high voltage direct current source (200), a contactor according to any one of claims 1 to 5 having a first electrical contact connected to the high voltage direct current source and a second electrical contact connected to a terminal (600) of the system for connection of a load.

7. An aircraft comprising an electrical power distribution system according to claim 6.