POWER CONTACTOR WITH ARC CLARIFICATION SCREEN AND AIRCRAFT FEATURING SUCH A POWER CONTACTOR

Abstract

The power contactor (100) comprises: - a fixed contact (102A); - a moving contact (104A); and - an electrically insulating screen (112) designed to move between a fully extended position and an interposed position between the fixed contact (102A) and the moving contact (104A) in its fully extended position. It further comprises: - a return device (116) designed to push the screen (112) from its fully extended position to its interposed position; and - a fuse (118) acting as a mechanical stop preventing the screen (112) from leaving its fully extended position, the fuse (118) being designed to trip to allow the screen (112) to move from its fully extended position to its interposed position under the effect of the return device (116), due to heat generated by an electric arc occurring between the fixed contact (102A) and the moving contact (104A). Figure for the abridged version: Fig. 1

Description

Title of the invention: POWER CONTACTOR WITH ELECTRIC ARC CLARIFICATION SCREEN AND AIRCRAFT COMPRISING SUCH A POWER CONTACTOR Technical field of the invention

[0001] The present invention relates to a power contactor with an electric arc clarification screen, as well as to an aircraft comprising such a power contactor. Technological background

[0002] Vertical take-off and landing (VTOL) aircraft and conventional take-off and landing (CTOL) aircraft with electric or hybrid propulsion constitute a market with significant prospects and demand in intra-urban and inter-urban transport for goods or people.

[0003] The propulsion of these different platforms is carried out by one or more electric motors, the number varying according to the architecture of the aircraft. These electric propulsion systems use ever higher direct voltage levels.

[0004] The failure modes of these systems show that the appearance of a series electric arc can have serious consequences on aircraft structures if the latter is not clarified (i.e. stopped).

[0005] However, an electric arc generally occurs between each pair of moving contact / fixed contact of a power contactor. If these electric arcs remained in place, they could cause a fire to start. This is why an arc blowing device is generally associated with the power contactor. However, if the arc blowing is faulty, the electric arc can cause a fire to start.

[0006] Furthermore, it is known to move an electrically insulating screen between the two fixed / movable contacts each time they are separated, see for example the international application published under number WO 1985 005218 AL Inserting the screen between the two contacts causes the electric arc to disappear. However, a carbon path may appear and strengthen each time the screen is used, gradually rendering it inoperative.

[0007] It may thus be desirable to provide a power contactor which makes it possible to overcome at least some of the aforementioned problems and constraints. Summary of the invention

[0008] A power contactor is therefore proposed comprising: - a fixed contact; - a movable contact designed to move relative to the fixed contact between a position in contact with the fixed contact to allow current flow and a position distant from the fixed contact to prevent current flow; and - an electrically insulating shield designed to move between a spaced position and a position interposed between the fixed contact and the movable contact in its distant position; characterized by: - a return device designed to push the screen from its spaced position to its interposed position; and - a fuse forming a mechanical stop preventing the screen from leaving its separated position, the fuse being designed to trigger in order to allow the screen to leave its separated position to reach its inserted position under the effect of the return device, under the effect of heat released by an electric arc appearing between the fixed contact and the moving contact.

[0009] The invention may further comprise one or more of the following optional features, in any technically possible combination.

[0010] Preferably, the power contactor further comprises: - another fixed contact; and - another movable contact designed to move relative to the other fixed contact between a position in contact with the other fixed contact to allow current flow and a position remote from the other fixed contact to prevent current flow, the two movable contacts being fixed to each other so as to move at the same time.

[0011] Also preferably, the screen is in the form of a plate, preferably perpendicular to a closing direction in which the movable contact moves between its spaced position and its interposed position.

[0012] Also preferably, the screen further comprises a bus bar to which the fixed contact is attached, and the fuse is attached to the bus bar.

[0013] Also preferably, the fuse has the shape of a pin, preferably rising parallel to the closing direction.

[0014] Also preferably, the return device comprises a spring.

[0015] Also preferably, the spring is extended between a fixed point and the screen.

[0016] Also preferably, the power contactor further comprises a device of blowing an electric arc appearing between the fixed contact and the moving contact.

[0017] An aircraft comprising a contactor according to the invention is also proposed. Brief description of the figures

[0018] The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which: - [Fig.l] is a three-dimensional view of an example of a power contactor according to the invention, - [Fig.2] is a block diagram of an example of the operating method of the power contactor of [Fig.l], - [Fig.3] is a view like that of [Fig.l], with electric arcs represented, and - [Fig.4] is a three-dimensional view of the power contactor of [Fig.l], after triggering an electric arc clarification screen. Detailed description of the invention

[0019] With reference to [Fig.l], an example of a power contactor 100 according to the invention will now be described.

[0020] The power contactor 100 comprises at least one pair of two contacts, one 102A, 102B being fixed and the other 104A, 104B being movable. The movable contact 104A, 104B is thus designed to move relative to the fixed contact 102A, 102B between a position in contact with the fixed contact 102A, 102B to allow current flow and a position remote from the fixed contact 102A, 102B to prevent current flow. The movement is done for example in a straight line, following a closing direction F.

[0021] For example, the power contactor 100 is double-break, as in the example illustrated, and comprises two pairs of fixed contacts 102A, 102B and movable contacts 104A, 102B. In this case, the two movable contacts 104A, 104B are fixed to each other so as to move at the same time. For example, the power contactor 100 comprises a movable bus bar 106 having two ends where the two movable contacts 104A, 104B are respectively fixed. Thus, the two movable contacts 104A, 104B are designed to move at the same time, with the bus bar 106, in the closing direction F to come into contact, substantially at the same time, with their associated fixed contact 102.

[0022] The power contactor 100 may further comprise, for each fixed contact 102A, 102B, a fixed bus bar 108A, 108B to which this fixed contact 102A, 102B is fixed.

[0023] The power contactor 100 may further comprise a device 110 for blowing out an electric arc appearing between each movable contact 104A, 104B and the associated fixed contact 102A, 102B, in particular when the power contactor 100 is opened. The blowing device 110 is designed to move and cause the electric arc to disappear. The movement of the electric arc is for example obtained by applying a magnetic field and its disappearance is for example obtained by dividing the electric arc into several smaller electric arcs.

[0024] The power contactor 100 further comprises an electrically insulating screen 112 associated with a fixed / moving contact pair (the pair 102A, 104A in the illustrated example). The screen 112 is designed to move between a spaced apart position, in which the screen 112 allows the moving contact 104A to move, and a position interposed between the fixed contact 102A and the moving contact 104A in its remote position to prevent the moving contact 104A from reaching its position in contact with the fixed contact 102A. The screen 112 is for example in the form of a plate, for example perpendicular to the closing direction F.

[0025] The screen 112 is preferably chosen from electrically insulating material with a high CTI (Comparative Tracking Index), for example at least 500 V, for example 600 V, in order to avoid the appearance of a carbon path likely to re-ignite the electric arc.

[0026] For example, the screen 112 is designed to move in a straight line, for example perpendicular to the closing direction F. To guide the movement of the screen 112, the power contactor 100 comprises for example a slide 114 for guiding the screen 112.

[0027] The power contactor 100 further comprises a return device 116 designed to push the screen 112 from its spaced position to its inserted position. For example, the return device 116 comprises a spring, for example in extension, between a fixed point A (for example of the slide 114) and the screen 112. Alternatively, the spring could be in compression.

[0028] The power contactor 100 further comprises a fuse 118 forming a mechanical stop for the screen 112, preventing the latter from leaving its spaced position, despite the force provided by the return device 116 to the screen 112. The fuse 118 is designed to trip under the effect of heat released by an electric arc appearing between the fixed contact 102A and the movable contact 104A. Following its triggering, the fuse 118 is designed to disintegrate and thus lose its stop function in order to allow the screen 112 to leave its spaced position to reach its inserted position under the effect of the return device 116. The fuse 118 is for example fixed on the fixed bus bar 108. Still for example, the fuse 118 has the shape of a pin preferably rising parallel to the closing direction F. The fuse 118 is for example made of a tin alloy.It has a trigger temperature (also called melting temperature), for example between 200°C and 250°C, for example 230°C.

[0029] With reference to [Fig.2], an example of a method 200 of operating the power contactor 100 of [Fig.1] will now be described.

[0030] Initially, the power contactor 100 is closed. The movable contacts 104A, 104B are respectively in contact with the fixed contacts 102A, 102B. Thus, a current passes as follows: through fixed bus bar 108A, then fixed contact 102A, then movable contact 104A, then movable bus bar 106, then movable contact 104B, then fixed contact 102B, then fixed bus bar 108B.

[0031] During a step 202, the power contactor is open. The movable contacts 104A, 104B move away from the fixed contacts 102A, 102B. Electric arcs then appear between the movable contact and the fixed contact of each pair respectively, as illustrated in [Fig. 3]. These electric arcs generate heat. In particular, part of the heat generated by the electric arc between the movable contact 104A and the fixed contact 102A diffuses by conduction into the fixed contact 102A, then into the fixed bus bar 108A, until it reaches the fuse 118 which heats up.

[0032] In normal operation of the power contactor 100, these arcs should be blown out by the blowing device 110, before the temperature of the fuse has reached its tripping threshold.

[0033] During a step 204, when the electric arcs are maintained for too long, for example more than a few tens of milliseconds, for example due to a failure of the blowing device 110, the temperature of the fuse 118 reaches the threshold and the fuse 118 trips and disintegrates. It thereby releases the screen 112.

[0034] Thus, during a step 206, the return device 116 pushes the screen 112 from its remote position to its position interposed between the movable contact 104A and the fixed contact 102A, as illustrated in [Fig. 4]. The sudden elongation of the electric arc due to the screen 112 creates an arc impedance sufficient for the counter electromotive force of the series arc to oppose the network voltage until the current is cut off.

[0035] In conclusion, it will be noted that the invention is not limited to the embodiments described above. It will indeed appear to those skilled in the art that various modifications can be made to the embodiments described above, in the light of the teaching which has just been disclosed to them.

[0036] In the detailed presentation of the invention which is made above, the terms used must not be interpreted as limiting the invention to the embodiments set out in the present description, but must be interpreted to include all equivalents whose prediction is within the reach of those skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.

Claims

Claims

1. Power contactor (100) comprising: - a fixed contact (102A); - a movable contact (104A) adapted to move relative to the fixed contact (102A) between a position in contact with the fixed contact (102A) to allow current flow and a position away from the fixed contact (102A) to prevent current flow; and - an electrically insulating screen (112) designed to move between a spaced position and a position interposed between the fixed contact (102A) and the movable contact (104A) in its remote position; characterized by: - a return device (116) designed to push the screen (112) from its spaced position to its interposed position; and - a fuse (118) forming a mechanical stop preventing the screen (112) from leaving its spaced position, the fuse (118) being designed to trigger in order to allow the screen (112) to leave its spaced position to reach its inserted position under the effect of the return device (116), under the effect of heat released by an electric arc appearing between the fixed contact (102A) and the movable contact (104A).

2. A power contactor (100) according to claim 1, comprising in besides : - another fixed contact (102B); and - another movable contact (104B) adapted to move relative to the other fixed contact (102B) between a position in contact with the other fixed contact (102B) to allow current flow and a position away from the other fixed contact (102B) to prevent current flow, the two movable contacts (104A, 104B) being fixed to each other so as to move at the same time.

3. A power contactor (100) according to claim 1 or 2, wherein the shield (112) is in the form of a plate, preferably perpendicular to a closing direction (F) in which the movable contact (104A) moves between its spaced position and its interposed position.

4. A power contactor (100) according to any one of claims 1 to 3, further comprising a bus bar (108A) to which the fixed contact (102A) is attached, and wherein the fuse (118) is attached to the bus bar (108A).

5. Power contactor (100) according to any one of claims 1 to 4, wherein the fuse (118) has the shape of a pin, preferably rising parallel to the closing direction (F).

6. A power contactor (100) according to any one of claims 1 to 5, wherein the return device (116) comprises a spring.

7. A power contactor (100) according to claim 6, wherein the spring is extended between a fixed point (A) and the screen (112).

8. Power contactor (100) according to any one of claims 1 to 7, further comprising a device (110) for blowing out an electric arc appearing between the fixed contact (102A) and the movable contact (104A).

9. Aircraft comprising a contactor according to any one of claims 1 to 8.

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