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EP-4740234-A1 - MAGNETIC HOLDING SYSTEM FOR A CONTACTOR

EP4740234A1EP 4740234 A1EP4740234 A1EP 4740234A1EP-4740234-A1

Abstract

The invention relates to a power contactor (100) comprising: - a fixed part (120); - a movable part (110) able to come into contact with the fixed part and to move between an open position and a closed position of the contactor, the movable part comprising two contact points (111, 112) for contact with the fixed part; - a first spring (141) placed on the movable part and configured to apply a pressing force on the movable part towards the fixed part; - an actuator (150) configured to actuate the movable part and bring it into contact with the fixed part; - an insulating support (101) containing the fixed part, the movable part and the first spring, characterized in that the power contactor also comprises: - a magnetic circuit (103) surrounding at least one portion of the movable part; and - a plate (102) fastened to the movable part and configured to come into contact with the magnetic circuit so as to form a closed magnetic circuit surrounding the movable part when the contactor is in the closed position, the insulating support also containing the plate and the magnetic circuit, and the distance (d1) between the plate and the magnetic circuit being strictly greater than the distance (d2) between the two contact points and the fixed part.

Inventors

  • ENOUF, Kévin
  • PRIEUR, Guillaume
  • PARAMAGURU, Vaseegan

Assignees

  • Safran Electrical & Power

Dates

Publication Date
20260513
Application Date
20240627

Claims (7)

  1. [Claim 1] Power contactor (100, 200, 300, 500) comprising: - a fixed part (120, 220, 320, 520); - a movable part (110, 210, 310, 510) capable of coming into contact with the fixed part and of moving between an open position and a closed position of the contactor, the movable part comprising two points of contact (111, 112, 211, 212, 311, 312, 511, 512) with the fixed part; - a first spring (141, 241, 341, 540) placed on the movable part and configured to apply a pressure force on the movable part towards the fixed part; - an actuator (150, 250, 350) configured to actuate the movable part and bring it into contact with the fixed part; - an insulating support (101, 201, 301, 501) containing the fixed part, the movable part and the first spring, characterized in that the power contactor also comprises: - a magnetic circuit (103, 203, 303, 503) surrounding at least a portion of the moving part; and - a plate (102, 202, 302, 502) fixed on the movable part and configured to come into contact with the magnetic circuit so as to form a closed magnetic circuit surrounding the movable part when the contactor is in the closed position, the insulating support also containing the plate and the magnetic circuit and the distance (dl) between the plate and the magnetic circuit being strictly greater than the distance (d2) between the two contact points and the fixed part when the contactor is in the open position or crossed by a nominal current.
  2. [Claim 2] A power contactor (100, 200, 300) according to claim 1, comprising a second spring (142, 242, 342) configured to apply a pressure force on the movable part towards the fixed part, the first (141, 241, 341) and the second (142, 242, 342) springs being placed opposite the two contact points of the fixed part.
  3. [Claim 3] The power contactor (500) of claim 1, wherein the magnetic circuit comprises two portions (503, 504) located on either side of the first spring (540), and the plate (502) is configured to form two closed magnetic circuits, with the two portions (503, 504) of the magnetic circuit surrounding the movable part when the contactor is in the closed position.
  4. [Claim 4] A power contactor according to any one of claims 1 to 3, wherein the magnetic circuit and the plate are made of ferromagnetic steel.
  5. [Claim 5] A power contactor according to any one of claims 1 to 4, wherein the distance between the plate and the magnetic circuit is between 2 mm and 4 mm, and the distance between the two contact points and the fixed part is between 1 mm and 2.5 mm.
  6. [Claim 6] Method for closing a power contactor in the open position according to any one of claims 1 to 5, comprising bringing the two contact points of the movable part into contact with the fixed part, the plate remaining at a distance from the magnetic circuit.
  7. [Claim 7] Method for opening a power contactor in the closed position, during a short circuit, according to any one of claims 1 to 5, comprising placing the plate in contact with the magnetic circuit, then opening the contact between the two contact points and the fixed part and finally opening the contact between the plate and the magnetic circuit.

Description

Description Title of the invention: Magnetic holding system for contactor Technical Domain The present invention relates to the general field of electrical protection devices, such as electromechanical contactors and electrical contactors, more particularly to the protection of these protection devices during a short circuit. Previous technique Power contactors are electrical protection devices generally made up of a fixed part and a moving part which may or may not be in contact with the fixed part. To close a contactor, and therefore put the moving part in contact with the fixed part so that an electric current can flow between the two parts, the contactor motor is powered which will apply a force to the moving part via a spring, and thus allow an electric current to flow between the two parts. When the current flowing between the two parts exceeds a predefined threshold, for example in the event of a short circuit, electromagnetic repulsion forces will be applied to the moving part and compensate for, or even exceed, the force applied by the spring to the moving part. This causes levitation of the contacts of the moving part, i.e. an unwanted opening of the contactor between the fixed and moving parts. In addition, during this phase, i.e. during levitation, the contact resistance between the fixed part and the moving part of the contactor increases and creates local heating (proportional to the contact resistance multiplied by the current squared) which can lead to the destruction of the moving part, irreversible damage to the contactor and/or welding of the moving part to the fixed part when the moving part falls back onto the fixed part after levitation. Currently, to avoid damage to the contactors in the event of a short circuit, that is to say to prevent the two parts of the contactor from welding together, several solutions exist: - The pressure force on the moving part is increased, but this requires a more bulky actuator, which is not compatible with aeronautics; - The number of contact points between the fixed part and the moving part can be multiplied, but this involves managing a large number of moving parts, which is difficult to implement on double-break contactors for linear motor actuation; - An expulsion circuit associated with a disconnection system can be used to open the moving part by magnetic repulsion and cut the circuit. There are therefore no means that are compact and fast enough to prevent the contactor from closing after levitation. It is therefore desirable to have a new contactor with a reduced risk of damage in the event of a short circuit. Disclosure of the invention The invention relates to a power contactor comprising: - a fixed part; - a movable part capable of coming into contact with the fixed part and of moving between an open position and a closed position of the contactor, the movable part comprising two points of contact with the fixed part; - a first spring placed on the movable part and configured to apply a pressure force on the movable part towards the fixed part; - an actuator configured to actuate the movable part and bring it into contact with the fixed part; and - an insulating support containing the fixed part, the moving part and the first spring, characterized in that the contactor also comprises: - a magnetic circuit surrounding at least a portion of the moving part; and - a plate fixed to the moving part and configured to come into contact with the magnetic circuit so as to form a closed magnetic circuit surrounding the moving part when the contactor is in the closed position, the insulating support also containing the plate and the magnetic circuit and the distance between the plate and the magnetic circuit being strictly greater than the distance between the two contact points and the fixed part. So when the contactor is in the closed position, during a short circuit, for example for a current flowing between the fixed part and the moving part of 1500 A, the contactor will levitate, so at least one of the contact points of the moving part will no longer be in contact with the fixed part, and the plate will move closer and come into contact with the magnetic circuit. The current still flowing in the moving part will therefore create its own magnetic field which will be channeled by the magnetic circuit and the plate; and a holding force is then created between the plate and the magnetic circuit which exceeds the pressure forces exerted by the spring on the moving part. The distance between the fixed part and the moving part is then of the order of 1 mm to 2 mm. This distance promotes the creation of higher electric arc voltages and therefore a limitation of the current. Thus, the short-circuit current is reduced. After a certain time related to the type of actuator, the distance between the fixed part and the moving part changes to a distance of 2 mm to 3 mm. The contactor is completely open. The electric arcs leave the area of the contact points of