SHORT CIRCUIT PROTECTION SYSTEM

Abstract

Short-circuit protection system (1) comprising a main branch (2) and a secondary branch (3) comprising a fuse, the system (1) comprising a pyrotechnic actuator (7a) comprising a gas generator (8a) and a piston movable between an initial position and a final position, said system (1) being configured to occupy the following positions: - a passive position; - an active position; characterized in that the secondary branch (3) comprises a movable slide which is integral with one end of the fuse and capable of being driven in translation under the action of the piston when the system (1) passes from its passive position to its active position, the system (1) being configured so that the slide imposes a rupture of the fuse which is subsequent to the opening of the main branch (2) when the system (1) passes from its passive position to its active position. Figure for the abstract: 1

Description

Title of the invention: SHORT-CIRCUIT PROTECTION SYSTEM Technical field of the invention

[0001] The present invention relates to a system for protecting against short circuits in a high voltage direct current electrical circuit. Technical background

[0002] A hybrid electric or all-electric aircraft is propelled using one or more electric thrusters, each comprising, for example, a propeller driven by an electric motor.

[0003] Depending on the different flight phases, each electric motor can be electrically powered via, for example, a turbogenerator and / or batteries.

[0004] A turbogenerator comprises a turboshaft engine and at least one electric generator, the electric generator transforming the mechanical power generated by the turboshaft engine into electric power intended to power the thrusters or to be stored in the batteries.

[0005] The electric thruster(s) are integrated into a high voltage direct current (HVDC) electrical circuit which is protected against short circuits via at least one protection system, the protection system making it possible to open the circuit and turn it off when a short circuit current is detected.

[0006] A short circuit is by definition dangerous and likely to cause more or less serious incidents, which is why short circuit protection systems are essential in an aircraft to guarantee passenger safety.

[0007] A known protection system comprises a main branch and a secondary branch connected in parallel. The secondary branch has a higher impedance than the main branch and comprises a fuse sized for a high intensity short-circuit current. More specifically, the fuse is sized to withstand, over a sufficiently long time, high intensity currents. The fuse is intended to open the secondary branch by melting one or more of its elements when a short-circuit current having a sufficient intensity to melt it passes through it. The system also comprises an actuator configured to open the main branch irreversibly when a high intensity short-circuit current is detected, and to force the short-circuit current to pass through the secondary branch and more particularly the fuse, to put defin- tively turn off the circuit.

[0008] Such a system is intended to protect the circuit against high intensity short-circuit currents which are generally the most dangerous in the short term. Indeed, the fuse of the secondary branch is sized to melt from a current of an intensity of the order of a hundred amperes while having a sufficiently long melting time, to completely extinguish the electric arc in the main branch, for currents of intensity of the order of thousands of amperes.

[0009] However, in the field of aeronautics, passenger safety must be total, it is therefore necessary to switch off the circuit as soon as a short-circuit current is detected and whatever its intensity (for example of the order of a milliampere for an insulation fault). Indeed, short-circuit currents of low or medium intensity can also be the cause of more or less serious incidents in the short term and / or in the more or less long term.

[0010] The objective of the present invention is therefore to propose a system for protecting against a short circuit in a high voltage direct current electrical circuit making it possible to ensure the opening of the main and secondary branches regardless of the intensity of the short-circuit current. Summary of the invention

[0011] The invention thus proposes a system for protecting against a short circuit in a high-voltage direct current electrical circuit, the system comprising a main branch and a secondary branch mounted in parallel and capable of being connected to the electrical circuit via two common input and output terminals, the secondary branch comprising a fuse and having an impedance greater than that of the main branch, the system comprising a pyrotechnic actuator comprising a gas generator and a piston movable between an initial position and a final position, said system being configured to occupy the following positions: - a passive position in which the piston is in its initial position, the main and secondary branches being closed; - an active position in which the piston is placed in its final position under the action of gas generated by said generator when a short-circuit current is detected, the main branch being open under the action of the piston; characterized in that the secondary branch comprises a movable slide which is integral with one end of the fuse and capable of being driven in translation under the action of the piston when the system passes from its passive position to its active position, the system being configured so that the slide imposes a rupture of the fuse which is subsequent to the opening of the main branch when the system passes from its passive position to its active position, so as to ensure an opening of the branch secondary regardless of the intensity of the short-circuit current.

[0012] The fact of introducing into the secondary branch a slide which imposes a rupture of the fuse under the action of the piston makes it possible to ensure an opening of the secondary branch (and therefore an opening of the system and of the circuit) in a determined time (preferably less than 5 ms), and this whatever the intensity of the short-circuit current.

[0013] Such a system is compatible for opening circuits supplied with 800 volts direct current in a time of less than 5 milliseconds, when they are subjected to short-circuit currents ranging from 0 to 10,000 amperes, with an L / R time constant greater than 0.1 milliseconds.

[0014] The system according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another: - the main branch comprises a first electrical contact between a fixed member and a first flexible leg, the system comprising a first separator which is movable in translation and secured to the piston, the first separator being configured to be interposed between the fixed member and the first flexible leg when the system is in its active position, so as to open the first electrical contact and consequently the main branch; - the slider has a first end fixed to the fuse and a second end fixed to a stopper movable in translation, the first separator being able to come to bear against a bearing face of the stopper to drive it in translation when the system passes from its passive position to its active position; - the first separator is located at a distance from the support face of the stopper when the system is in the passive position; - the main branch comprises a second electrical contact between the fixed member and a second flexible leg, the system comprising a second separator which is movable in translation and secured to both the piston and the first separator, the second separator being parallel to the first separator, the second separator being configured to be interposed between the fixed member and the second flexible leg when the system is in its active position, so as to open the first and second electrical contacts and consequently the main branch; - the fixed member is interposed between the first and second separators on the one hand and between the first and second legs on the other hand, the first and second legs being respectively in contact with the upper face and the lower face of the fixed member when the system is in the passive position; - the first and second separators each have a chamfer configured to facilitate the opening of the first and second electrical contacts; - the first and second legs are symmetrical and meet at a common sole which is connected to the common output terminal, each of the first and second legs comprising a convex section and a concave section in contact with the fixed member when the system is in the passive position; - each of the first and second separators is guided in translation between a structure of the system and the fixed member; - the main and secondary branches are horizontally next to each other, the actuator being vertically above the first and second separators and the main branch; - the first and second separators are secured to the piston via a connecting element, the first and second separators and the piston being movable in translation in the same direction of movement, when the system passes from a passive position to an active position; - the first and second separators are secured to the piston via a lever articulated relative to a structure of the system, the first and second separators being movable in translation in a direction of movement which is opposite to that of the piston, when the system passes from a passive position to an active position; - the actuator comprises a rod having a first end fixed to the piston and a second end carrying a first pin inserted into a first oblong hole of the lever, the system comprising a connecting element having a first end secured to the first and second separators and a second end carrying a second pin inserted into a second oblong hole of the lever, the lever being articulated between the first and second oblong holes.

[0015] The present invention also relates to an electrical circuit comprising at least one electric thruster and a short-circuit protection system as described above.

[0016] The present invention further relates to an aircraft comprising an electrical circuit as described above. Brief description of the figures

[0017] The invention will be better understood and other details, characteristics and advantages of the invention will appear more clearly on reading the following description given by way of non-limiting example and with reference to the appended drawings in which:

[0018] [Fig-1] [Fig.l] is a perspective view of a system for protecting against a short circuit, according to a first embodiment of the invention;

[0019] [Fig.2] [Fig.2] is a sectional view of the system illustrated in [Fig.l] along section plane II-II of [Fig.l];

[0020] [Fig.3] [Fig.3] is a sectional view of the system illustrated in [Fig.l] along section plane III-III of [Fig.l];

[0021] [Fig.4] [Fig.4] is a sectional view comparable to that of [Fig.2] illustrating a second embodiment of the invention. Detailed description of the invention

[0022] Figures 1 to 4 show a short-circuit protection system 1 according to the invention.

[0023] Such a system 1 is intended to be integrated into a high voltage direct current electrical circuit (better known by the English acronym “HVDC” for “High Voltage Direct Current”) of an aircraft.

[0024] Advantageously, such a circuit comprises at least one electric thruster intended to propel the hybrid electric or all-electric aircraft. The electric thruster is for example a propeller driven by an electric motor.

[0025] Such a circuit is powered via, for example, a turbogenerator and / or batteries. The supply voltage is, for example, 800 volts.

[0026] As illustrated in the figures, the system 1 comprises a main branch 2 and a secondary branch 3 connected in parallel. The main and secondary branches 2, 3 are connected to the electrical circuit via a common input terminal 4 and a common output terminal 5. The secondary branch 3 comprises a fuse 6. The secondary branch 3 has an impedance greater than that of the main branch 2. The system 1 comprises a pyrotechnic actuator 7a, 7b comprising a gas generator 8a, 8b and a piston 9a, 9b movable between an initial position and a final position.

[0027] System 1 is configured to occupy the following positions: - a passive position in which the piston 9a, 9b is in its initial position, the main and secondary branches 2, 3 being closed; - an active position in which the piston 9a, 9b is placed in its final position under the action of gas generated by the generator 8a, 8b when a short-circuit current is detected, the main branch 2 being opened (or cut) under the action of the piston 9a, 9b.

[0028] According to the invention, the secondary branch 3 comprises a movable slider 10 which is integral with one end of the fuse 6 and capable of being driven in translation under the action of the piston 9a, 9b when the system 1 passes from its passive position to its active position. The system 1 is configured so that the slider 10 imposes a break in the fuse 6 which is subsequent to the opening of the main branch 2 when the system 1 passes from its passive position to its active position, so as to ensure the opening (or cutting) of the secondary branch 3 regardless of the intensity of the short-circuit current.

[0029] As indicated above, when the system 1 is in the passive position, the main and secondary branches 2, 3 are closed. The system is by default in position passive, and in other words in a position in which the current can flow in the main and secondary branches 2, 3. The system is in the passive position when the circuit operates normally, that is to say without a short circuit.

[0030] As indicated above, when the system 1 is in the active position, the main and secondary branches 2, 3 are open. The system is switched to the active position when a short circuit is detected in the circuit and regardless of its intensity. Switching to the active position makes it possible to open the system and more generally the circuit to protect in particular the electric thrusters and the surrounding installations.

[0031] The fact of introducing into the secondary branch 3 a slide 10 which imposes a rupture of the fuse 6 under the action of the piston 9a, 9b makes it possible to ensure an opening of the secondary branch 3 (and therefore an opening of the system and of the circuit) in a determined time (preferably less than 5 ms), and this whatever the intensity of the short-circuit current.

[0032] The secondary branch 3 is used to open the system 1 (and therefore the circuit) in a controlled manner, when a short circuit is detected. The opening of the main branch 2 is prior to directing the short-circuit current into the secondary branch 3, and thus controlling the opening of the system 1 (and therefore the circuit).

[0033] Depending on the intensity of the short-circuit current, the fuse 6 breaks under the action of a mechanical stress (namely the force imposed by the slide and initiated by the piston) and / or under the action of a thermal stress (namely the heat linked to the passage of the short-circuit current).

[0034] Thus, for example, when the short-circuit current is of low intensity, the fuse breaks mainly or completely under the action of the aforementioned mechanical stress. Conversely, when the short-circuit current is of high intensity, the fuse breaks mainly or completely under the action of the aforementioned thermal stress.

[0035] The fuse 6 is configured to interrupt an electric arc potential formed at the time of its rupture (and thus allow the opening of the secondary branch). An electric arc is particularly likely to be created when the short-circuit current is of medium or high intensity. To quickly stop an electric arc potential, the fuse 6 comprises a material intended to absorb the thermal energy released when it ruptures, for example silica. The silica will in fact melt under the action of the electric arc then vitrify to become an excellent insulator interrupting the electric arc.

[0036] Advantageously, the system 1 additionally comprises at least one degassing element which is arranged near the fuse 6 to participate in interrupting the electric arc.

[0037] As illustrated in [Fig. 3], the system 1 here comprises two degassing elements 54 arranged at each of the ends of the fuse 6, each degassing element 54 being in the form of a polymer disc which is configured to release a gas participating in the interruption of the electric arc when it is thermally stressed.

[0038] As indicated above, the fuse 6 is sized for a high intensity short-circuit current. More precisely, the fuse 6 is sized to withstand, over a sufficiently long time, high intensity currents, so as to allow the main branch 2 to open beforehand. “High intensity” for a short-circuit current means a current greater than 1000 amperes, for example 8000 amperes.

[0039] As indicated above, the impedance of the secondary branch 3 is greater than that of the main branch 2.

[0040] Advantageously, the current of the secondary branch 3 is at least 100 times lower than that of the main branch 2, so that the current flows mainly through the main branch 2, when the system 1 is in the passive position, to the benefit of the lifetime of the secondary branch 3 (and therefore of the system) and the consumption of the system 1.

[0041] The system 1 (and more particularly the actuator) is controlled by a control device, this control device being informed of the presence or absence of a short circuit by a sensor (for example a coil sensor) integrated or not in the system 1. The control device orders the system 1 to switch to the active position as soon as a short circuit is detected and whatever its intensity. The intensity of the short-circuit current can be for example between 0 and 10000 amperes.

[0042] According to the embodiments illustrated in Figures 1 to 4, the system 1 comprises a housing 11 (partially shown) in which the main and secondary branches as well as the pyrotechnic actuator 7a, 7b are integrated. The housing 11 forms an insulating and sealed chamber, so as to protect in particular the elements located inside from the external environment, and vice versa. The system 1 comprises a structure 12 arranged inside the housing 11 and on which the various elements of the system 1 are mounted. The structure 12 can be formed with the housing 11 or separately from the housing 11. The main and secondary branches 2, 3 are horizontally next to each other, the actuator 7a, 7b being vertically above the first and second separators 13, 14 and the main branch 2.The common input and output terminals 4, 5 (also called input and output power bar) are each in the form of an electrical bar provided with a captive screw 15 to allow its connection to the circuit.

[0043] According to the embodiments illustrated in Figures 1 to 4, the main branch 2 comprises in particular a fixed member 17 and two flexible legs 18, 20 (from the terminal input to output terminal).

[0044] More specifically, as illustrated in Figures 2 and 4, the main branch 2 comprises a first electrical contact 16 between the fixed member 17 and a first flexible leg 18 and a second electrical contact 19 between the fixed member 17 and a second flexible leg 20. The first and second electrical contacts 16, 19 are closed when the system 1 is in the passive position and open when the system 1 is in the active position. The first and second contacts 16, 19 are thus normally closed.

[0045] The fixed member 17 is interposed between the first and second legs 18, 20. The first and second legs 18, 20 overlap the fixed member 17 when the system 1 is in the passive position. The first and second legs 18, 20 are respectively in contact with the upper face and the lower face of the fixed member 17 when the system 1 is in the passive position. The fixed member 17 is here integral with the input terminal 4, and in other words the fixed member 17 and the input terminal 4 are in the form of a single piece.

[0046] The first and second legs 18, 20 are symmetrical and meet at a common sole 21 which is connected to the common output terminal 5. Each of the first and second legs 18, 20 comprises a convex section 22 and a concave section 23 in contact with the fixed member 17 when the system 1 is in the passive position.

[0047] According to a variant not shown, the main branch 2 could comprise a single electrical contact, namely either the first electrical contact or the second electrical contact.

[0048] According to the embodiments illustrated in Figures 1 to 4, the system 1 comprises a first separator 13 and a second separator 14.

[0049] More precisely, as illustrated in Figures 2 to 4, the first and second separators 13, 14 are parallel, movable in translation and integral with the piston 9a, 9b.

[0050] When the system 1 is in the passive position (figures 2 and 4), the separators 13, 14 are at a distance from the first and second electrical contacts 16, 19.

[0051] When the system 1 is in the active position (not shown), the first separator 13 is configured to be interposed between the fixed member 17 and the first flexible tab 18, and the second separator 14 is configured to be interposed between the fixed member 17 and the second flexible tab 20, so as to open the first and second electrical contacts 16, 19 and consequently the main branch 2.

[0052] The first and second separators 13, 14 are each in the form of a blade, the separators 13, 14 having equivalent dimensional characteristics.

[0053] Advantageously, the first and second separators 13, 14 each have a chamfer 24 configured to facilitate the opening of the first and second contacts. electrical 16, 19.

[0054] More precisely, as illustrated in Figures 2 and 4, each chamfer 24 is external so that the inclined plane of the chamfer 24 is substantially parallel to the free end of the concave section 23 of the corresponding tab 18, 20.

[0055] The first and second separators 13, 14 are arranged on either side of the fixed member 17, each of the first and second separators 13, 14 being guided in translation between the fixed member 17 and the structure 12 of the system 1.

[0056] According to the embodiments illustrated in Figures 1 to 4, the secondary branch 3 comprises in particular the fuse 6, the slider 10 and a stopper 25 (from the input terminal to the output terminal).

[0057] As indicated above, the fuse 6 is sized to withstand, over a sufficiently long time, high intensity currents, and configured to interrupt an electric arc potential formed at the time of its rupture.

[0058] More precisely, the fuse 6 is arranged in an insulating and sealed enclosure 26 of the structure 12. The fuse 6 is in the form of a metal strip perforated at a regular pitch (here 9 perforations). The fuse 6 has a first end fixed to the slide 10 via a screw 27 and a second end fixed to the input terminal 4 via a screw 28.

[0059] The slider 10 is mounted to move in translation in a housing 29 of the structure 12. The slider 10 is in the form of a shouldered axis, the shoulder being permanently located in the housing 29. The slider 10 has a first end fixed to the fuse 6 via the screw 27 and a second end fixed in a blind hole 30 of the stopper 25 via a screw 31.

[0060] The stopper 25 has an L-shape in section, and comprises a vertical portion 32 fixed to the slider 10 and a horizontal portion 33. The stopper 25 comprises a horizontal slot 34, the bottom of which forms a bearing face 35 which is here vertical.

[0061] When the system 1 moves from its passive position ([Fig.3]) to its active position, the first separator 13 is able to come to bear against the bearing face 35 of the stopper 25 to drive it in translation, and thus drive the slide 10 in translation so as to mechanically stress the fuse 6 in traction. The first separator 13 is located at a distance from the bearing face 35 of the stopper 25 when the system 1 is in the passive position. Such a predetermined distance makes it possible to thermally stress the fuse 6 before stressing it mechanically, so as to facilitate its rupture.

[0062] The stopper 25 is electrically connected to the output terminal 5 via a braid 36, the braid 36 having in particular one end fixed to the horizontal portion 33 of the stopper 25 via a screw 37 (see [Fig.3]).

[0063] According to the first embodiment illustrated in Figures 1 to 3, the system 1 comprises an actuator 7a in a configuration called a “retractor”.

[0064] Such an actuator 7a comprises a body 38a attached to the structure 12, a piston 9a movable in translation in a chamber 39a of the body 38a and a gas generator 8a arranged in the body 38a and connected with the chamber 39a.

[0065] At the request of the control device, when a short-circuit current is detected, the pyrotechnic actuator 7a is triggered (or fired), so that the piston 9a is placed in the final position under the action of gas generated by the generator 8a, and thus drives the separators 13, 14 and the slider 10 (via the separators and the stopper).

[0066] More specifically, the gas generator 8a comprises a pyrotechnic charge (or cartridge) (for example propellant in the form of pellets) and a device for igniting (or priming) the pyrotechnic charge, the gas generated by the combustion of the pyrotechnic charge makes it possible to move the piston 9a into its final position. The gas generator 8a is placed in an upper cavity 40 of the chamber 39a. The generated gas can be released directly into the chamber 39a or only when a threshold is reached (for example a pressure threshold).

[0067] The piston 9a is secured to the first and second separators 13, 14 via a connecting element 41a (or separator holder) made of electrically insulating material (for example plastic).

[0068] The piston 9a, the first and second separators 13, 14, the stopper 25 and the slider 10 are movable in translation in the same direction of movement (symbolized by the arrow 42 in FIGS. 1 to 3), when the system 1 passes from a passive position to an active position.

[0069] The actuator 7a further comprises a locking device (for example a pin not shown) to lock the piston 9a in the final position and a damping device 43 (damper having a honeycomb structure) to dampen the piston 9a at the end of its stroke.

[0070] According to the second embodiment illustrated in [Fig.4], the system 1 comprises an actuator 7b in a configuration called a “pusher”.

[0071] The elements common to the first and second embodiments retain the same numerical references.

[0072] Such an actuator 7b comprises a body 38b attached to the structure 12, a piston 9b movable in translation in a chamber 39b of the body 38b, a rod 44 secured to the piston 9b and a gas generator 8b arranged in the body 38b and connected with the chamber 39b.

[0073] At the request of the control device, when a short-circuit current is detected, the pyrotechnic actuator 7b is triggered (or fired), so that the piston 9b is placed in the final position under the action of gas generated by the generator 8b, and thus drives the separators 13, 14 (via the lever) and the slider 10 (via the se- parators and the stopper).

[0074] More specifically, the gas generator 8b comprises a pyrotechnic charge (or cartridge) (for example propellant in the form of pellets) and a device for igniting (or priming) the pyrotechnic charge, the gas generated by the combustion of the pyrotechnic charge makes it possible to move the piston 9b into its final position. The gas generator 8b is placed in the bottom of the chamber 39b. The generated gas can be released directly into the chamber 39b or only when a threshold is reached (for example a pressure threshold).

[0075] The first and second separators 13, 14 are integral with the piston 9b via a lever 45 (or rocker arm) articulated relative to the structure 12 of the system 1. More precisely, the rod 44 of the actuator 7b has a first end fixed to the piston 9b and a second end carrying a first pin 46 inserted into a first oblong hole 47 of the lever 45. The system 1 further comprises a connecting element 41b (or separator holder) made of electrically insulating material (for example plastic). The connecting element 41b has a first end secured to the first and second separators 13, 14 and a second end carrying a second pin 48 inserted into a second oblong hole 49 of the lever 45. The lever 45 is articulated in its middle, that is to say between the first and second oblong holes 47, 49, around a substantially horizontal axis of rotation. The first and second oblong holes 47, 49 extend radially relative to the axis of rotation of the lever 45.

[0076] The first and second separators 13, 14 are movable in translation in a first direction of movement (symbolized by the arrow 50 in [Fig.4]) which is opposite to a second direction of movement of the piston 9b (symbolized by the arrow 51 in [Fig.4]), when the system 1 passes from a passive position to an active position. The stopper 25 and the slider 10 are movable in translation in the first direction of movement, when the system 1 passes from a passive position to an active position.

[0077] The actuator 7b further comprises a damping device 52, 53 (progressive immobilization of the conical portion 52 of the rod in the conical portion 53 of the body 38b) to dampen the piston 9b at the end of its stroke.

[0078] Compared to the first embodiment (Figures 1 to 3), the second embodiment has the advantage of being lighter and more compact.

Claims

Claims

1. A short-circuit protection system (1) in a high-voltage direct current electrical circuit, the system (1) comprising a main branch (2) and a secondary branch (3) mounted in parallel and capable of being connected to the electrical circuit via two common input and output terminals (4, 5), the secondary branch (3) comprising a fuse (6) and having an impedance greater than that of the main branch (2), the system (1) comprising a pyrotechnic actuator (7a, 7b) comprising a gas generator (8a, 8b) and a piston (9a, 9b) movable between an initial position and a final position, said system (1) being configured to occupy the following positions: - a passive position in which the piston (9a, 9b) is in its initial position, the main and secondary branches (2, 3) being closed; - an active position in which the piston (9a, 9b) is placed in its final position under the action of gas generated by said generator (8a, 8b) when a short-circuit current is detected, the main branch (2) being open under the action of the piston (9a, 9b); the secondary branch (3) comprising a movable slider (10) which is integral with one end of the fuse (6) and capable of being driven in translation under the action of the piston (9a, 9b) when the system (1) passes from its passive position to its active position, the system (1) being configured so that the slider (10) imposes a rupture of the fuse (6) which is subsequent to the opening of the main branch (2) when the system (1) passes from its passive position to its active position, so as to ensure an opening of the secondary branch (3) whatever the intensity of the short-circuit current; characterized in that the main branch (2) comprises a first electrical contact (16) between a fixed member (17) and a first flexible leg (18), the system (1) comprising a first separator (13) which is movable in translation and secured to the piston (9a, 9b), the first separator (13) being configured to be interposed between the fixed member (17) and the first flexible leg (18) when the system (1) is in its active position, so as to open the first electrical contact (16) and consequently the main branch (2).

2. System (1) according to claim 1, characterized in that the slider (10) has a first end fixed to the fuse (6) and a second end fixed to a stopper (25) movable in translation, the first separator (13) being able to come to bear against a bearing face (35) of the stopper (25) to drive it in translation when the system (1) passes from its passive position to its active position.

3. System (1) according to claim 2, characterized in that the first separator (13) is located at a distance from the bearing face (35) of the stopper (25) when the system (1) is in the passive position.

4. System (1) according to one of claims 1 to 3, characterized in that the main branch (2) comprises a second electrical contact (19) between the fixed member (17) and a second flexible leg (20), the system (1) comprising a second separator (14) which is movable in translation and secured to both the piston (9a, 9b) and the first separator (13), the second separator (14) being parallel to the first separator (13), the second separator (14) being configured to be interposed between the fixed member (17) and the second flexible leg (20) when the system (1) is in its active position, so as to open the first and second electrical contacts (16, 19) and consequently the main branch (2).

5. System (1) according to the preceding claim, characterized in that the fixed member (17) is interposed between the first and second separators (13, 14) on the one hand and between the first and second legs (18, 20) on the other hand, the first and second legs (18, 20) being respectively in contact with the upper face and the lower face of the fixed member (17) when the system (1) is in the passive position.

6. System (1) according to one of claims 4 to 5, characterized in that the first and second separators (13, 14) each have a chamfer (24) configured to facilitate the opening of the first and second electrical contacts (16, 19).

7. System (1) according to one of claims 4 to 6, characterized in that the first and second legs (18, 20) are symmetrical and meet at a common sole (21) which is connected to the common output terminal (5), each of the first and second legs (18, 20) comprising a convex section (22) and a concave section (23) in contact with the fixed member (17) when the system (1) is in the passive position.

8. System (1) according to one of claims 4 to 7, characterized in that each of the first and second separators (13, 14) is guided in translation between a structure (12) of the system (1) and the fixed member (17).

9. System (1) according to one of claims 4 to 8, characterized in that the main and secondary branches (2, 3) are horizontally next to each other, the actuator (7a, 7b) being vertically above the first and second separators (13, 14) and the main branch (2).

10. System (1) according to one of claims 4 to 9, characterized in that the first and second separators (13, 14) are integral with the piston (9a) via a connecting element (41a), the first and second separators (13, 14) and the piston (9a) being movable in translation in the same direction of movement, when the system (1) passes from a passive position to an active position.

11. System (1) according to one of claims 4 to 9, characterized in that the first and second separators (13, 14) are integral with the piston (9b) via a lever (45) articulated relative to a structure (12) of the system (1), the first and second separators (13, 14) being movable in translation in a direction of movement which is opposite to that of the piston (9b), when the system (1) passes from a passive position to an active position.

12. System (1) according to claim 11, characterized in that the actuator (7b) comprises a rod (44) having a first end fixed to the piston (9b) and a second end carrying a first pin (46) inserted into a first oblong hole of the lever (45), the system (1) comprising a connecting element (41b) having a first end secured to the first and second separators (13, 14) and a second end carrying a second pin (48) inserted into a second oblong hole (49) of the lever (45), the lever (45) being articulated between the first and second oblong holes (47, 49).

13. Electrical circuit comprising at least one electric thruster and a short-circuit protection system (1) according to one of the preceding claims.

14. An aircraft comprising an electrical circuit according to claim 13.

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