WO2014207111A1 - Electrical contactor and method for controlling such a contactor - Google Patents

Abstract

The electrical contactor according to the invention comprises at least one pair of fixed contacts (22) and, for the or each pair of fixed contacts (22), a contact (24) that is movable between a closed position and an open position. The contactor comprises a contact carrier (26) able to hold the or each mobile contact (24). The contact holder (26) is movable between a first position corresponding to the closed position of the movable contact (24) and a second position corresponding to the open position of the movable contact (24). The contactor comprises a first magnetic part (28) secured to the movable contact carrier and placed across from the or each movable contact, an actuator able to control the movement of the movable contact carrier (26), according to a control law, and a current sensor able to measure the current flowing through each pair of fixed contacts (22) and each associated movable contact (24). The control law of the actuator comprises moving the movable contact carrier (26) from its first position to its second position when a current with a value above a predetermined threshold is measured by the current sensor. The first magnetic part (28) is then moved by the movable contact carrier (26), and bears against the movable contact (24) and goes toward its open position.

Description

 ELECTRICAL CONTACTOR AND METHOD FOR CONTROLLING SUCH

 SWITCH

The present invention relates to an electric contactor and a method of controlling such a contactor.

 The electrical contactor comprises at least one pair of fixed contacts and, for each pair of fixed contacts, a movable contact between a closed position and an open position. More specifically, the fixed contacts are electrically connected to each other, when the movable contact is in the closed position, and electrically isolated from each other, when the movable contact is in the open position. The contactor also includes a contact holder adapted to maintain the movable contact and a first magnetic part secured to the contact carrier and placed opposite the moving contact. The contactor comprises an actuator adapted to control the displacement of the contact carrier between a first position corresponding to the closed position of the movable contact and a second position corresponding to the open position of the movable contact.

 The contactor is generally included in an electrical installation and placed downstream of a protection device, such as a fuse or a circuit breaker, intended to ensure the protection of the installation in the event of a short circuit, when the moving contact is in closed position and also when closing the movable contact.

In general, it is known that when the moving contact and the fixed contacts are traversed by short-circuit currents or more generally over-currents, the moving contact and the fixed contacts are subjected to repulsive forces, which tend to open the unwanted mobile contact by electrodynamic effect. Thus, as soon as the current has reached an overcurrent threshold, the repulsive forces are large enough to cause the opening of the moving contact, which results in the appearance of an electric arc between the fixed and movable contacts. When the current decreases, either naturally (sinusoidal current), or thanks to the limitation of the current due to the action of the circuit breaker, the repulsion forces decrease, so that the moving contact closes. However, when opening the movable contact, contact pads positioned on the fixed and movable contacts are strongly heated by the electric arc and are in a pasty or liquid phase, so that there is a significant risk of welding of the movable contact with the fixed contacts, in addition to other risks of destruction of the contactor due to the stresses generated by the electric arc, and wear of the contacts. A persistent challenge in the field of electrical contactors is that the contactor is coordinated with the protective device, that is to say, it does not endanger the electrical installation or its user.

 In the field of contactors, it is known from FR-A1-2559308 to have a contactor whose magnetic element is connected to the movable contact carrier via a magnetic suction cup. In this type of contactor, when the movable contact is closed, the magnetic element provides a magnetic force own to maintain the movable contact in the closed position. The contactor is set so that, for a defined value of a fault current flowing through the fixed contacts and the corresponding moving contact, the magnetic suction cup disengages from the movable contact carrier. Thus, when this fault current value is reached, the magnetic element is detached from the mobile contact carrier and becomes inoperative. As a result, a sudden change in the resulting repulsive force between the fixed and movable contacts is obtained since the magnetic element no longer holds the moving contact in the closed position. Rapid opening of the moving contact will therefore occur because of the repulsive force applied between the fixed contacts and the moving contact.

 However, the contactor must be set so that the magnet sucks off for a defined fault current value, causing a sufficient repulsion force, which guarantees the complete opening of the mobile contact without welding or destruction. However, the detachment of the magnetic sucker for the defined value of fault current is difficult to obtain precisely because it is a mechanical solution of tearing, and the repulsive force caused by the sucker is sensitive among other things at the temperature. In addition, the total opening of the moving contact is only guaranteed for high fault current values, involving a large repulsion force between the fixed contacts and the moving contact.

 The object of the invention is therefore to provide an electrical contactor to ensure better coordination with a protective device such as a circuit breaker, that is to say by limiting the risk of welding or destruction of the contactor during the occurrence of a fault current for a wide range of fault currents.

For this purpose, the subject of the invention is an electrical contactor comprising at least one pair of fixed contacts and, for the or each pair of fixed contacts, a movable contact between a closed position and an open position, the fixed contacts being, in the closed position of the movable contact, electrically connected to each other via the movable contact and being electrically isolated from each other in the open position of the movable contact. The contactor also includes a contact holder adapted to maintain the or each movable contact, preferably via a spring, the contact carrier being movable between a first position corresponding to the closed position of the movable contact and a second position corresponding to the open position of the movable contact, as well as a first magnetic piece secured to the movable contact holder and placed opposite the or each movable contact. The contactor also comprises an actuator capable of controlling the displacement of the movable contact carrier between its first and second positions, according to a control law, and a current sensor capable of measuring the current flowing through each pair of fixed contacts and each contact. associated mobile. According to the invention, the control law of the actuator comprises the displacement of the movable contact carrier from its first position to its second position when a current of value greater than a predetermined threshold is measured by the current sensor, the first magnetic part being then displaced by the movable contact holder and bearing against the movable contact and to its open position.

 Thanks to the invention, when the value of the current flowing through the fixed contacts and each associated moving contact is less than the predetermined threshold, each moving contact remains in closed position without soldering, and when the value of the current flowing through the fixed contacts and each moving contact associated is greater than the predetermined threshold, the opening of the movable contact is guaranteed by moving the movable contact carrier from its first position to its second position. Thus, when the appearance of a current of value greater than the predetermined threshold, the moving contact opens quickly without welding or destruction of the contactor.

 According to other advantageous aspects of the invention, the electric contactor further comprises one or more of the following characteristics, taken individually or in any technically permissible combination:

 the electric contactor comprises a coil and an electronic control module, the electronic control module being able to drive a driving current through the coil according to a driving law, the coil being able to control the displacement of the movable contact carrier as a function of the running through it,

 the current sensor is, for the or each pair of fixed contacts, positioned around one of the fixed contacts,

 when the current sensor measures a current below the predetermined threshold and when the moving contact is in the closed position, the corresponding first magnetic part forms with the moving contact a first gap,

the or each first magnetic part is integral with the movable contact carrier, the or each first magnetic part is secured to the movable contact carrier by overmolding,

 - The movable contact holder holding by means of a spring or each movable contact, while for the or each movable contact, the contactor comprises a second magnetic part, integral with the movable contact and against which the spring is in support , and while when each movable contact is in the closed position, the second magnetic part forms a second air gap with the first magnetic part,

 when the mobile contact (s) are in the closed position, the corresponding first and second magnetic parts are adapted to apply a closing force to the corresponding mobile contact tending to keep the moving contact in the closed position,

 when the mobile contact (s) are in the closed position, the corresponding first and second magnetic parts are capable of exerting an opening force on the movable contact carrier in the direction of movement of the movable contact carrier from its first position towards its second position.

 The invention also relates to a method of controlling a contactor comprising at least one pair of fixed contacts and, for the or each pair of fixed contacts, a movable contact between a closed position and an open position, the fixed contacts. being, in the closed position of the movable contact, electrically connected to each other via the movable contact and being electrically isolated from each other in the open position of the movable contact. The contactor also comprises a contact-holder suitable for holding the or each movable contact, preferably by means of a spring, the contact carrier being movable between a first position corresponding to the closed position of the movable contact and a second position. corresponding to the open position of the movable contact, and a first magnetic piece secured to the movable contact carrier and placed opposite the or each movable contact. The contactor also comprises an actuator capable of controlling the displacement of the movable contact carrier between its first and second positions, according to a control law, and a current sensor capable of measuring the current flowing through each pair of fixed contacts and each contact. associated mobile. According to the invention, the method comprises, when controlling the opening of the or each movable contact, the following steps:

 a) measuring a value of the current flowing through each pair of fixed contacts and each associated moving contact,

b) comparing the measured value with a predetermined threshold, c) controlling the displacement of the movable contact carrier from its first position to its second position when the measured value is greater than the predetermined threshold, the first magnetic part then being displaced by the movable contact carrier and bearing against the contact mobile and to its open position.

 According to other advantageous aspects of the invention, the method of controlling an electric contactor further comprises one or more of the following characteristics, taken separately or in any technically permissible combination:

 during step c) the first magnetic part exerts an opening force on the movable contact carrier in the direction of its displacement,

 for the or each movable contact, the contactor comprises a second magnetic part, while in step c) the second magnetic part increases the opening force exerted on the movable contact carrier in the direction of its displacement .

 The invention will be better understood and other advantages thereof will emerge in the light of the description which follows, given solely by way of nonlimiting example, and with reference to the appended drawings in which:

 - Figure 1 is a schematic perspective view of a three-phase contactor according to the invention;

 FIG. 2 is a perspective representation of a switching block of the contactor of FIG. 1;

 - Figure 3 is a sectional view along the plane III of Figure 2;

 - Figure 4 is a sectional view along the plane IV of Figure 2;

 - Figure 5 is a view similar to that of Figure 3, the movable contact being in the open position;

 - Figure 6 is a view similar to that of Figure 4, the movable contact being in the open position;

 FIG. 7 is a set of four curves representing, as a function of time, the current flowing through the fixed contacts and the associated moving contact, the arc voltage between the fixed contacts and the associated moving contact, the movement of a moving vane. the actuator and moving the movable contact; and

 - Figure 8 is a flowchart of a control method according to the invention.

In FIG. 1, a three-phase contactor comprises three switching blocks 12, an actuator 14, three current sensors 16 and an electronic control module 18. The contactor 10 thus comprises, for each phase, a switching block 12 and a current sensor 16.

 In a variant, the electronic module 18 comprises both a control member and a processing member, not shown.

 The switching block 12, shown in FIG. 2, comprises two fixed contacts

22 and a movable contact 24 between a closed position and an open position. The fixed contacts 22 are, in the closed position of the movable contact 24, electrically connected to each other via the movable contact 24, and are electrically isolated from one another in the open position of the movable contact 24.

 Z is a vertical direction in which each moving contact moves.

 X denotes a longitudinal direction along which a pair of fixed contacts 22 extends, the longitudinal direction X being perpendicular to the vertical direction Z.

 Y is a transverse direction in which the switching blocks 12 are aligned, the transverse direction Y being perpendicular to the vertical direction Z and the longitudinal direction X.

 The switching unit 12 also comprises a contact holder 26 capable of holding and driving in translation, in the vertical direction Z, each moving contact 24.

 The switching unit 12 comprises a first magnetic part 28 and a second magnetic part 30.

 The actuator 14 comprises a movable ferromagnetic pallet 32 mechanically connected to the contact carrier 26, a ferromagnetic portion 33 and a coil 34 adapted to control the movement of the mobile pallet 32. The coil 34 is connected to the electronic module 18 via an electrical connection 36.

 The actuator 14 is able to control the movement of the movable pallet 32, and by mechanical connection, the contact carrier 26 according to a control law.

 Each current sensor 16 is able to measure the current flowing through the corresponding pair of fixed contacts 22. Each current sensor 16 is positioned around one of the two fixed contacts 22 specific to each switching block 12.

The control module 18 is able to compare the current measured by each current sensor with a predetermined threshold and to drive, according to a control law, a current flowing through the coil 34, so as to interrupt the current flowing through the coil When the current measured by at least one current sensor 16 is greater than the predetermined threshold.

 Each fixed contact 22 comprises a contact pad 38. The two fixed contacts 22 specific to each switching block 12 respectively correspond to a current input terminal and a current output terminal.

 Each movable contact 24 comprises a central portion 39 and two contact pads 40.

 The contact carrier 26 is movable between a first position corresponding to the closed position of the movable contact 24 and a second position corresponding to the open position of the movable contact 24. The movable contact holder 26 supports the movable contact 24 via a first spring 42 positioned between the movable contact holder 26 and the second magnetic part 30, knowing that the second magnetic part 30 is mechanically connected to the movable contact 24 or resting against the moving contact 24.

 The first magnetic piece 28 is next to the second magnetic piece

30 and the movable contact 24. More precisely, the first magnetic part 28 has, in the vertical plane comprising the transverse direction Y, corresponding to the section plane IV, the shape of a U defining a central zone 44, two lateral branches 46 , 48 and an opening 50, as shown in Figure 4. The first magnetic part 28 is integral with the movable contact holder 26. The first magnetic part 28, is preferably overmolded in the movable contact holder 26 or simply maintained by the The first magnetic part 28, more precisely its central zone 44, forms a first air gap E1 with the movable contact 24 when the movable contact 24 is in the closed position. The first air gap E1 makes it possible to guarantee wear protection of the contact pads 38, 40.

 The second magnetic part 30 is secured to the movable contact 24, by coupling or simple support, against the corresponding central portion 39. It is connected to the movable contact holder 26 by the first spring 42. The second magnetic piece 30 is generally flat parallel to a plane passing through the longitudinal direction X and the transverse direction Y.

The first magnetic part 28 and the second magnetic part 30 are arranged and dimensioned so that a second air gap E2, which is not zero, remains between the two magnetic parts 28 and 30 in the closed position of the moving contact 24, whatever the degree of wear of the contact pads 38, 40. The first magnetic part 28 and the second magnetic part 30 are arranged to form the opening 50 in which the central portion 39 is located. They thus form, with the movable contact 24, an electromagnetic sub-assembly of the electromagnet type.

 The first magnetic part 28 and the second magnetic part 30 are clean, when the movable contact 24 is in the closed position and traversed by a current, to produce a first force F1, also called closing force, in the vertical direction Z, tending to keep the movable contact 24 in the closed position.

 The movable pallet 32 is able to move the movable contact holder 26 between its first position and its second position. The control module 18 is thus able to trigger the movement of the movable pallet 32 from its first position to its second position by interrupting the current flowing through the coil 34 as a function of the information it receives from the current sensors 16.

 The coil 34 is able to control the displacement of the movable contact holder 26 as a function of the current flowing through it.

 The central portion 39 is, in the vertical plane comprising the longitudinal direction X, corresponding to the section plane III, T-shaped with the two ends of the horizontal bar of the T which support the two contact pads 40 (Figure 3). In the vertical plane comprising the transverse direction Y (section plane IV), the central portion 39 is blade-shaped (Figure 4).

 The first spring 42 is, when the movable contact 24 is in the closed position, able to exert a pressure force, in the vertical direction Z, to ensure a pressure of the movable contact 24 against the corresponding fixed contacts 22. When the movable contact 24 is in the closed position, the first gap E1 is not zero. Furthermore, when the movable contact 24 is moved to the open position, that is to say that the movable pallet 32 and the movable contact holder 26 are moved in order to open the movable contact 24, the spring 42 is suitable for exerting a second force F2, along the vertical axis Z, on the movable contact holder 26 so as to accelerate the opening of the movable contact 24.

 In Figures 3 and 4, the movable contact 24 is in the closed position, and the first gap E1 and the second gap E2 are non-zero.

In Figures 5 and 6, the movable contact 24 is in the open position, and the first gap E1 and the second air gap E2 are substantially zero. The first gap is preferably between 0.5 millimeters (mm) and 1.5 mm, more preferably equal to 0.8 mm and the second air gap is preferably between 0.1 mm and 1 mm, more preferably equal to 0.5 mm. When the movable contact 24 is moved to the open position, it moves in the vertical direction Z opposite the corresponding fixed contacts 22, that is to say downwards.

 When the movable contact 24 is moved in the closed position, it moves in the vertical direction Z to the corresponding fixed contacts 22, that is to say upwards.

 When the movable contact 24 is closed, a current flows through the fixed contacts 22 and the movable contact 24. The first 28 and second 30 corresponding magnetic parts generate the first force F1 on the movable contact 24, and more particularly on its central part. 39, so as to maintain the movable contact 24 in the closed position.

 As the movable contact 24 is in the closed position, it abuts against the fixed contacts 22 and the first force F1 generates a third force F3, also called the opening force, which tends to attract the first magnetic part 28 towards the moving contact. 24, that is, down. Knowing that the first magnetic part 28 is overmolded in the contact holder 26, the third force F3 is also exerted on the contact holder 26 and thus on the mobile pallet 32 which is connected thereto. Thus, the third force F3 is exerted on the moving pallet 32 of the actuator 14 in the direction of the opening of the actuator 14, that is to say the opening of the movable contact 24.

 Furthermore, when a current flows in the movable contact 24, a fourth repulsion force F4 is generated, in the vertical direction Z, between the movable contact 24 and the corresponding fixed contacts 22, and urges the opening of the movable contact 24 However, the first force F1 and the pressure force exerted on the movable contact 24 keep the moving contact 24 in the closed position, and the actuator 14 remains closed thanks to a holding current flowing in the coil. 34. The holding current is controlled by the control module 18.

 Then, when the current, flowing in the movable contact 24 and measured by the corresponding current sensor 16, reaches a level too high and exceeds the predetermined threshold (it is, for example, a short-circuit current) , the control module 18 detects this exceeding threshold.

The control module 18 is then able to interrupt the holding current in the coil 34 by applying the control law. Thus, the holding current of the actuator 14 in the closed position is interrupted, and the force exerted on the movable pallet 32 in the direction of the opening of the movable contact 24, and therefore the opening of the actuator 14, becomes greater than the closing force of the actuator 14. The moving pallet 22 thus moves the movable contact holder 26 towards its second position, ie towards the bottom, under the effect:

 the second force F2 exerted by each first spring 42 on the moving pallet 32,

 the third force F3 exerted by each first magnetic part 28 on the actuator 14 in the direction of its opening, that is to say the displacement of the movable contact holder 26 towards the second position, and

 - A fifth force F5, not shown, applying in the vertical direction Z, the fifth force F5 being exerted by a second spring, not shown, for returning the actuator 14.

 The combination of these three forces F2, F3, F5 allows the acceleration of the movement of the pallet 22, and therefore the movable contact holder 26 to its second position. This acceleration is even greater than the first force F1 which generates the third force F3 is high.

 The predetermined threshold is set according to the size of the contactor 10.

Generally, this threshold is between ten and twenty times a nominal current In of an electrical installation on which the contactor 10 is connected, preferably substantially equal to fifteen times the nominal current In.

 The pallet 32 has an opening stroke much larger than the first gap E1 since it must also ensure the opening distance of the movable contact 24 relative to the fixed contacts 22. The movable pallet 32 moves downwards, and causes the movable contact holder 26 to move downwards, so that each first gap E1 and each second gap E2 decreases and becomes substantially zero, and each first magnetic piece 28 comes into contact with the corresponding movable contact 24 and move it to the open position.

 When the mobile pallet 32 has traveled the first gap E1, it has reached a high speed. The first magnetic parts 28 then come into contact with the corresponding central parts 39 and a subassembly formed of the mobile pallet 32, the movable contact holder 26, the first magnetic parts 28 and the movable contacts 24 move at a speed sufficient to ensure correct opening of the movable contacts 24, that is to say without risk of welding of the latter on the corresponding fixed contacts 22, and without risk of destruction of the contactor 10. The movable pallet 32 is moved to full opening of each mobile contact 24.

Indeed, the first magnetic parts 28 strike the corresponding mobile contact 24 with a significant kinetic energy due to the strong acceleration of the movable pallet 32, due in particular to the first force F1. The first magnetic parts 28 thus cause the opening of the movable contact 24, and prevent the closure thereof after a repulsion thereof under the effect of electrodynamic forces, corresponding to the fourth force F4. In addition, in the limit case where the movable contact 24 closes after an opening due to the repulsion force, the opening speed of the pallet 32 implies that the movable contact 24 does not have time to be welded on the corresponding fixed contacts 22 before being struck by the first piece 28.

 Moreover, the currents being different in each phase, that is to say in each switching block 12, the contactor 10 comprises three current sensors 16 and it is the first of the three current sensors 16 which detects a current fault, of value greater than the predetermined threshold, which triggers, via the control module 18, the interruption of the holding current of the actuator 14 and the opening of the actuator 14.

 In Figure 7, four curves C1, C2, C3, C4 are shown. The first, second, third, and fourth curves C1, C2, C3, C4 respectively represent, for a contactor 10 comprising a single switching block 12, the evolution of the current flowing through the moving contact 24, of the arc voltage between the movable contact 24 and the corresponding fixed contacts 22, the displacement of the movable contact 24 and the movement of the pallet 32, as a function of time, during the occurrence of an electrical fault and the control by the actuator 14 of the opening of the movable contact 24. The first curve C1 corresponds to a negative current I, while the second curve C2 corresponds to a negative voltage V. The third and fourth curves C3, C4 correspond to a displacement ΔΖ, along the Z axis, expressed as a function of the position of the moving pallet 32. The displacement ΔΖ is considered as zero when the movable pallet 32 is in the closed position, c that is, the coil is traversed by the holding current. When the movable pallet 32 moves and drives the movable contact holder 26 to its second position, the displacement has, by convention, been chosen to have a negative value in FIG. 7, this displacement being directed downwards.

It appears that when the first curve C1 exceeds the predetermined threshold, this time t1 is shown in Figure 7, the movement of the movable pallet 32 in the opening direction occurs following the interruption of the current flowing through the coil 34 by the control module 18. This movement is controlled according to the control law. Then, from a certain processing time, the fourth curve C4 begins to decrease, which corresponds to the displacement of the moving pallet 32. However, before the displacement of the moving contact 24, the first air gap E1 is non-zero, and must be traveled by the movable pallet 32 so that it comes, through the first magnetic part 28, to take charge of the movable contact 24, that is to say in abutment against the movable contact 24.

 The control law comprises the displacement of the movable contact holder 26 from its first position to its second position when a current of value greater than the predetermined threshold is measured by the current sensor 16. The control law comprises the movement of the pallet mobile 32, and therefore the movable contact holder 26, when a current of value greater than the predetermined threshold is measured.

 Thus, when a current exceeds the predetermined threshold, and when the movable contact holder 26 connected to the mobile pallet 32 has not yet taken charge of the movable contact 24, it is observed on the third curve C3 according to the level of the current exceeding the predetermined threshold, that the movable contact 24 begins to be moved to the open position, then to close, under the effect of the fourth force F4. It thus appears, as visible on the curve C2, a non-zero arc voltage, negative value, between the movable contact 24 and the corresponding fixed contacts 22. However, before the movable contact 24 closes completely, it is observed that the curve C4 and the curve C3 come together, which implies that the pallet 32 and the first magnetic part 28 assume contact with the movable contact 24. The movable contact 24 is then in the open position before it has been welded to the corresponding fixed contacts 22. This moment of support t2 is visible in FIG.

 During the application of the control law, the first magnetic part 28 is thus displaced by the movable contact holder 26 towards the open position of the movable contact 24 and bears against the movable contact 24.

 The time between the beginning of repulsion of the movable contact 24 and the management of the movable contact 24 by the first magnetic part 28 is too short for the movable contact 24 to be welded to the corresponding fixed contacts 22. Then, once the movable contact 24 is far enough away from the corresponding fixed contacts 22, the current becomes zero again, the electric arc then goes out and the arc voltage becomes zero, as visible on the first and second curves C1 and C2. Then the movable pallet 32 continues its displacement, and the displacement of the movable contact holder 26, until complete opening of the movable contact 24.

When the movable pallet 32 has moved the movable contact holder 26 until the complete opening of the movable contact 24, the displacement value ΔΖ has a negative value and is therefore minimal, according to the representation conventions chosen for FIG. 7. A method of controlling the opening of the electric contactor 10, that is to say the movable contact 24 and the actuator 14, during the detection of a short-circuit current comprises various steps. A first measurement step 100 consists in measuring the value of the current flowing through the movable contact 24 and the corresponding fixed contacts 22 by means of the current sensor 16.

 Then a second comparison step 102 consists of comparing said current value with the predetermined threshold.

 In a third displacement step 104, when said current value is greater than the predetermined threshold, the actuator 14, and more precisely the control module 18, interrupts the supply current flowing through the coil 34, and thus controls, thanks to the control law and following the control law, the movement of the movable pallet 32 and, by mechanical connection, the movable contact carrier 26 from its first position to its second position. During this third step 104, the movable contact carrier 26 moves the first magnetic part 28, by mechanical connection, so that the first magnetic part 28 bears against the movable contact 24 and to its open position.

 The moving pallet 32 continues its movement and causes the displacement of the first magnetic part 18 until the complete opening of the movable contact 24.

 During the third step 104, the first magnetic part exerts the first force F1 which generates the third force F3 on the moving pallet 32 and on the movable contact holder 26 in the direction of its displacement, which accelerates the movement of the contact. mobile 24 in the open position.

 The first magnetic part 28 has a double effect, that of keeping the corresponding mobile contact 24 in the closed position, when the current flowing through the corresponding fixed contacts 22 is less than the predetermined threshold, and that of accelerating the opening of the actuator 14 and the corresponding movable contact 24, when the current flowing through the corresponding fixed contacts 22 is greater than the predetermined threshold.

 The second magnetic part 30 makes it possible to increase the third force F3 exerted on the movable contact holder 26 in the direction of its displacement from its first position to its second position, when the current flowing through the coil 34 is interrupted.

 As a variant, the value of the predetermined threshold can be parameterized, this value being adjustable via, for example, an encoder wheel system.

According to another variant, the contactor 10 is a single-phase contactor. In this variant, the contactor 10 comprises a single switching block 12. The contactor 10 then comprises a single pair of fixed contact 22 and a single movable contact 24. The other elements of the contactor 10 according to this variant are identical to the embodiment described above, and are not described again.

 According to another variant, a single air gap among the first gap E1 and the second gap E2 is substantially zero when the movable contact 24 is in the open position.

 The contactor 10 is adapted to be used either alone, in particular for reduced levels of short-circuits, thus ensuring itself the protection of an electrical installation to which it is connected, or in association with a circuit breaker placed upstream of a current supply for higher levels of short circuits.

 The fact that the control law of the actuator comprises the displacement of the movable contact holder 26 from its first position to its second position when a current of value greater than the predetermined threshold is measured by the current sensor 16, is equivalent to that the control law comprises an order for controlling the displacement of the movable contact holder 26 from its first position to its second position when a current of value greater than the predetermined threshold is measured by the current sensor 16, the first magnetic part 28 being then moved by the movable contact holder 26 and bearing against the movable contact 24 and to its open position.

Claims

1. - Electric contactor (10), comprising:  - At least one pair of fixed contacts (22) and, for the or each pair of fixed contacts (22), a contact (24) movable between a closed position and an open position, the fixed contacts (22) being in position closed of the movable contact (24), electrically connected to each other via the movable contact (24) and being electrically isolated from one another in the open position of the movable contact (24),  - a contact holder (26) adapted to hold the or each movable contact (24), preferably via a spring (42), the contact holder (26) being movable between a first position corresponding to the closed position of the movable contact (24) and a second position corresponding to the open position of the movable contact (24),  a first magnetic part (28) integral with the movable contact carrier and placed facing the or each movable contact,  an actuator (14) capable of controlling the displacement of the movable contact carrier (26) between its first and second positions, according to a control law,  a current sensor (16) capable of measuring the current flowing through each pair of fixed contacts (22) and each associated movable contact (24),  characterized in that the control law of the actuator comprises an order to control the movement of the movable contact carrier (26) from its first position to its second position when a current of value greater than a predetermined threshold is measured by the current sensor (16), the first magnetic part (28) then being displaced by the movable contact carrier (26) and bearing against the movable contact (24) and towards its open position. 2. - Contactor according to claim 1, characterized in that the electrical contactor (10) comprises a coil (34) and an electronic module (18) for driving, according to a control law, a current flowing through the coil (34). ), the coil (34) being adapted to control the movement of the movable contact carrier (26) as a function of the current flowing therethrough. 3. - Contactor according to one of the preceding claims, characterized in that the current sensor (16) is, for the or each pair of fixed contacts (22), positioned around one of the fixed contacts (22). 4. - Contactor according to one of the preceding claims, characterized in that when the current sensor (16) measures a current lower than the predetermined threshold and the movable contact (24) is in the closed position, the first magnetic part (28) ) is adapted to form with the movable contact (24) a first gap (E1). 5. - Contactor according to one of the preceding claims, characterized in that the or each first magnetic part (28) is integral with the movable contact carrier (26). 6. Contactor according to claim 5, characterized in that the or each first magnetic part (28) is secured to the movable contact carrier (26) by overmolding. 7. - Contactor according to one of the preceding claims, characterized in that the movable contact carrier (26) maintains by means of a spring (42) the or each movable contact (24), in that for the or each movable contact (24), the contactor comprises a second magnetic part (30), integral with the movable contact (24) and against which the spring (42) bears, and in that when each movable contact (24) is in the closed position, the second magnetic piece (30) forms a second gap (E2) with the first magnetic piece (28). 8. - Contactor according to any one of the preceding claims taken with claim 7, characterized in that when the one or more movable contacts (24) are in the closed position, the first (28) and second (30) corresponding magnetic parts are adapted to apply a closing force (F1) on the corresponding movable contact (24) tending to maintain the movable contact (24) in the closed position. 9. - Contactor according to any one of the preceding claims taken with claim 7, characterized in that when the movable contact (s) (24) are in the closed position, the first (28) and second (30) corresponding magnetic parts are adapted to exert an opening force (F3) on the movable contact carrier (26) in the direction of movement of the movable contact carrier (26) from its first position to its second position. 10. - Method of controlling an electric contactor, the contactor comprising: - At least one pair of fixed contacts (22) and, for the or each pair of fixed contacts (22), a contact (24) movable between a closed position and an open position, the fixed contacts (22) being in position closed of the movable contact (24), electrically connected to each other via the movable contact (24) and being electrically isolated from one another in the open position of the movable contact (24),  - a contact holder (26) adapted to hold the or each movable contact (24), preferably via a spring (42), the contact holder (26) being movable between a first position corresponding to the closed position of the movable contact (24) and a second position corresponding to the open position of the movable contact (24),  a first magnetic part (28) integral with the movable contact carrier and placed facing the or each movable contact,  an actuator (14) capable of controlling the displacement of the movable contact carrier (26) between its first and second positions, according to a control law,  a current sensor (16) capable of measuring the current flowing through each pair of fixed contacts (22) and each associated movable contact (24),  the method being characterized in that it comprises, when controlling the opening of the or each movable contact (24), the following steps:  a) measuring a value of the current flowing through each pair of fixed contacts (22) and each associated movable contact (24),  b) comparing the measured value with a predetermined threshold,  c) controlling the displacement of the movable contact carrier (26) from its first position to its second position when the measured value is greater than the predetermined threshold, the first magnetic part (28) then being displaced by the movable contact carrier ( 26) and bearing against the movable contact (24) and towards its open position. 1 1. - Method according to claim 10, characterized in that during step c) the first magnetic part (28) exerts an opening force (F3) on the movable contact carrier (26) in the direction of its moving from its first position to its second position. 12. - Method according to claim 1 1, characterized in that for the or each movable contact (24), the contactor (10) comprises a second magnetic part (30), and in that during step c ) the second magnetic part (30) increases the force opening (F3) exerted on the movable contact carrier (26) in the direction of its displacement.