Electrical switching device having an auxiliary contact

Abstract

The invention relates to an electrical switching device comprising a fuse which is used to open a power line through which a direct current flows, a movable drawer (16B, 34, 36) being connected to the fuse and being capable, once the fuse has blown, of being moved into a fixed chamber (22; 22A) by a compression spring mounted between the fixed chamber and the movable drawer, and an auxiliary contact, a fixed contact portion (320A, 320B) of which is rigidly attached to the fixed chamber and a movable contact portion (322A, 322B) of which is rigidly attached to the movable drawer whose movement will cause the normally closed auxiliary contact to open.

Description

Technical Field

[0001] The present invention relates to the general field of electrical switching devices for direct current power supply networks, preferably high voltage (HVDC) and more particularly for aircraft propulsion systems. Previous technique

[0002] The electrical disconnect system known as a "pyrofuse" or "pyroswitch" is an assembly consisting of a pyrotechnic actuator and a fuse triggered by the actuator. It is used to open a power line carrying direct current in the event of a short circuit or excessive current. The pyrotechnic actuator then acts to assist the fuse in opening the power line under extreme conditions through the combined action of the melting of the fusible element and a mechanical stretching action that helps to break the fuse. There are also electrical disconnect systems with mechanical actuators, or even some without any actuator at all.

[0003] While such devices are generally satisfactory, it is difficult to ensure that the fuse has blown or that the actuator has triggered correctly when it exists, as well as to detect a possible dormant failure of the device which cannot be operational without a fuse in good working order when the power line is opened.

[0004] US patent 2013 / 200984 describes an electrical disconnect device in which a compression spring is placed against a spool. Upon detection of an electrical fault, the spool, under the force of the spring, moves to interrupt the electrical current. Description of the invention

[0005] The main purpose of this invention is therefore to ensure constant monitoring of the fuse's state throughout its entire lifespan, regardless of its activation mode. Another purpose is to ensure that the auxiliary contact detecting this state has reached its end of travel.

[0006] These goals are achieved by an electrical switching device comprising a fuse used to open a power line in which a direct current flows, characterized in that it further comprises a movable drawer connected to the fuse and capable, once the fuse is broken, of moving in a fixed chamber under the action of a compression spring mounted between the fixed chamber and the movable drawer, and an auxiliary contact of which a fixed contact part is integral with the fixed chamber and a movable contact part is integral with the movable drawer whose movement will cause the opening of the normally closed auxiliary contact.

[0007] Advantageously, the auxiliary contact is galvanically isolated from the power line.

[0008] The addition of this auxiliary circuit for detecting breakage, galvanically isolated from the power circuit, ensures the monitoring function of the fuse's condition, regardless of its activation mode, whether short circuit, pyrotechnical or mechanical activation.

[0009] Preferably, the movable drawer is fixed to one end of the fuse by a first fixing screw.

[0010] Advantageously, the movable drawer consists of a slide that moves in the fixed chamber and a stop that rests against the fixed chamber and is fixed to the slide by a second fixing screw.

[0011] Preferably, the fixed and moving contact parts of the auxiliary contact are each made up of a copper strip and a silver pellet.

[0012] Advantageously, the moving contact part is mounted on an insulating plate fixed to the stop by third fixing screws.

[0013] Preferably, the auxiliary contact is connected to a Sub-D connector to actuate an external signaling process.

[0014] According to one embodiment, the cutting device comprises a limit switch contact with a copper strip and a silver disc.

[0015] Preferably, the fuse is triggered by a pyrotechnic or mechanical actuator.

[0016] The invention also relates to a high-voltage direct current (HVDC) power supply network comprising a switching device as described above and an aircraft propulsion system comprising such a high-voltage direct current power supply network. Brief description of the drawings

[0017] Other features and advantages of the present invention will become apparent from the description given below, with reference to the accompanying drawings which illustrate an example of an embodiment without being limiting in any way and on which: [Fig. 1 ] there figure 1 is a cross-sectional view in a passive position of a switching device according to the invention, [ Fig. 2 ] there figure 2 is a cross-sectional view in an active position of a switching device according to the invention, and [ Fig. 3 ] there figure 3 is seen from an external perspective of the switching device figures 1 And 2 at the level of its auxiliary contact. Description of the implementation methods

[0018] The principle of the invention is based on the fact that as soon as an overcurrent passes through the fuse of the electrical cutting device and melts it, a drawer equipped with an auxiliary contact is no longer held by this fuse and then moves in a chamber under the action of a compression spring put under pressure and which thus returns to its free position, releasing the auxiliary contact, so as to signal the breakage of the fuse whose monitoring can thus be ensured.

[0019] THE figures 1 And 2 They show, by way of example, in two different positions, an electrical disconnect device 10 consisting of a pyrotechnical or mechanical actuator 12 and a fuse 14 triggered by the actuator, and used to open a power line carrying a high-voltage direct current. The pyrotechnical or mechanical actuator itself is not described in detail.

[0020] In first position of the figure 1 The switching device is at rest, the fuse 14 of the device is in perfect condition and extends between a first fixed end 14A and a second movable end 14B attached to a movable slide 16 by a first fixing screw 18. The slide can move in translation within a housing 20 of a fixed chamber 22 mounted in the body 10A of the switching device. The movable slide is advantageously made in two parts with a slide 16A and a stop 16B. The slide 16A is mounted to move in translation within the housing 20 and is in the form of a shouldered shaft, the shoulder 160 being permanently located in the housing 20. The slide 16A has a first end fixed to the fuse 14 via the first fixing screw 18 and a second end fixed in a blind hole 24 of the stop 16B via a second fixing screw 26.The stop 16B fixed to the slide 16A by the second fixing screw 26 puts under tension a compression spring 28 (which then has a length in place Lp) until it is pressed against the fixed chamber 22 via a connecting ring 30 mounted in the housing 20 and whose thickness corresponds to that of the shoulder 160. An auxiliary contact 32, a fixed contact part 32A of which is integral with the fixed chamber 22 (more precisely with an offset part 22A of this fixed chamber visible at the . figure 3 ) and a movable contact part 32B facing it, integral with the movable drawer 16 (more precisely directly from the stop 16B or via an insulating plate 34 fixed by third fixing screws 36 to the stop (visible at the figure 3 (Depending on the material of the stop), is designed to detect the pull-out (melting) of the fuse. The movement of the fuse, via the slide 16A and the compression spring 28, will cause this normally closed (NC) auxiliary contact to open in the rest position of the breaking device. Each fixed or moving contact consists of a copper strip 320A, 320B and a silver disc 322A, 322B. The contact of the two silver discs signifies the closure of the auxiliary contact. Note the galvanic isolation formed between this auxiliary contact and the power line due to the absence of a conductive connection between them.

[0021] The two copper strips of the two fixed and moving contact parts are connected by wiring to a Sub-D type connector (not shown) which allows the state of the auxiliary contact to be read and thus the state of the fuse of the electrical cut-off device to be monitored and known.

[0022] In second position of the figure 2 , the fuse 14 melted under the action of heat or broke for some other undesired reason and the slide 16A sliding in the fixed chamber 22 was therefore translated under the action of the compression spring 28 which then returns to its free length L0.

[0023] Indeed, this slide 16A, attached to one end of the fuse 14, is capable of being moved in translation under the action of the compression spring when the cutting device 10 moves from its rest position, therefore passive, to an active operating position, bringing its shoulder 160 against the connecting ring 30 held by the compression spring 28 against the fixed chamber 22. The bearing face 162 of the stop 16B is now separated from the fixed chamber against which it rested via the connecting ring 30, this separation setting in motion the normally closed auxiliary contact 32. The moving contact part 32B fixed to the stop 16B is then set in motion and disengages from the opposite fixed contact part 32A fixed to the fixed chamber 5, the auxiliary contact then being in the open position.

[0024] It should be noted that when the normally closed auxiliary contactor is, as illustrated, coupled with a normally open auxiliary contact (NO 38), consisting of another copper strip 380 and a silver disc 382, ​​it is possible to ensure that the system has reached the end of its travel under the action of the compression spring 28.

Claims

1. An electrical cut-off device (10) including a fuse (14) used to open a power line in which a direct current circulates, the device further includes a movable drawer (16; 16A, 16B) connected to the fuse and capable, once the fuse is broken, of moving in a fixed chamber (22) under the action of a compression spring (28) mounted between the fixed chamber and the movable drawer, and an auxiliary contact (32) whose fixed contact part (32A) is secured to the fixed chamber and movable contact part (32B) is secured to the movable drawer whose movement will cause the opening of the normally closed auxiliary contact, the device being characterized in that the auxiliary contact is galvanically isolated from the power line.

2. The cut-off device according to claim 1, wherein the movable drawer is fixed to one end of the fuse by a first fixing screw (18).

3. The cut-off device according to claim 1, wherein the movable drawer is made up of a slide (16A) sliding in the fixed chamber and of a stopper (16B) bearing against the fixed chamber and fixed to the slider by a second fixing screw (28).

4. The cut-off device according to any one of claims 1 to 3, wherein the auxiliary contact is connected to a Sub-D connector in order to actuate an external signaling process.

5. The cut-off device according to any one of claims 1 to 4, wherein the fixed and movable contact parts of the auxiliary contact are each constituted by a copper strip (320A, 320B) and a silver pad (322A, 322B).

6. The cut-off device according to claim 5, wherein the movable contact part is mounted on an isolation plate (34) fixed to the stopper by third fixing screws (36).

7. The cut-off device according to any one of claims 1 to 6, further including a limit switch contact (38) with a copper strip (380) and a silver pad (382).

8. The cut-off device according to any one of claims 1 to 7, wherein the fuse is triggered by a pyrotechnic or mechanical actuator (12).

9. A high-voltage direct current (HVDC) supply network including a cut-off device according to claim 8.

10. An aircraft propulsion system including a high-voltage direct current supply network according to claim 9.

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