EP0665564B1 - Driving mechanism for a protective breaker - Google Patents

Abstract

The moving contact in a vacuum chamber (1) is operated by a rod (4) connected to a displacement device (5) which is driven by a conductive helical spring (6) of shape memory alloy. Excessive current on the protected line passes through the spring, producing enough heat to switch the alloy from the martensitic to the austenitic phase. An abrupt movement is executed through the dead point constituted by the longitudinal axis of the chamber. Reclosure can be effected by a sequencer (8) comprising three retractable and two non-retractable cams (81-83;84,85) and three pneumatic jacks (87-89).

Description

The present invention relates to a mechanism actuating the movable contact of a protective switching chamber, according to the preamble of claim 1 (see for example DE-A-2928799).

It relates more precisely to a mechanism actuating the movable contact of a switch-off chamber protection installed on a power line and to be open to the appearance of an overcurrent threshold on the line, this mechanism comprising a driving motor member a contact displacement device.

When a fault occurs on the line, you must detect this fault, for example a short circuit, and open the breaking chamber then once the fault current gone, order the room to be closed. These detections and these commands are carried out in a conventional manner using electronic systems, with energy input outside.

The present invention provides such a mechanism particularly simple and reliable, requiring no external control system.

To do this, according to the invention, the mechanism is characterized in that it allows the closing of the breaking chamber thanks to a sequencing device associated with the displacement device and ensuring an adjustable and timed cycle of openings and closures.

The particular properties of shape memory alloys combined with sizing adequate spring, so that it under the effect of a fault current, for example greater than ten times the nominal current, heats up to a level such as alloy goes from the martensitic phase to the austenitic phase, this which causes the shape of the spring to change (from a state expansion to a state of compression or vice versa) and activates the movement device causing the opening of the switching chamber.

According to the invention, the mechanism comprises a device sequencer which delays the reclosing and the possible reopening of the switching chamber according to a cycle adjustable openings and closings, for example according to a O-2s-FO-10s-FO-20s-F cycle, and when the fault remains present locks the mechanism in the open position.

According to the preferred embodiment of the invention, the movement device is an action mechanism abrupt on either side of a neutral point, connected to the contact mobile and movable from a first position where it pushes the contact in the closed position to a second position where it pulls the contact in the open position under the effect of compression of the form alloy spring connected by one of its ends to this displacement device by through a sliding rod inside the spring and abutting at this end when the spring is relaxed and by its other end connected to a fixed support part.

The displacement device has two arms rotatable around an axis, the first being rotated by a tension spring and being connected to the movable contact via a connecting rod pivotable and by an arrangement comprising a guided part in a guide rigidly connected to the contact, urged by a compression spring and having an oblong hole in which can slide the pivot axis of the connecting rod and the second being integral with the sliding rod.

The sequencing device comprises at least one cam retractable by means of a time delay on which are in traction a hook fixed to the free end of the sliding rod and engaged push a roller also attached to the free end of the sliding rod.

Preferably, the sequencing device comprises several retractable cams aligned on a rotating wheel subject to a return spring and a swivel hook on a fixed axis retaining one of these cams against the action of the return spring.

The sequencing device also has two cams non retractable end position locking.

In order to allow manual resetting of the mechanism, the sequencing device comprises an independent means manual clearing of all cams for resetting of this device at the end of the cycle.

In order to allow automatic resetting of the mechanism, the sequencing device includes a means independent of automatic erasure of all cams to reset this device during the cycle, comprising a pneumatic cylinder supplied with gas, by via a valve controlled by a timer pneumatic, by a compression chamber where a piston linked to the displacement device.

The invention is described below in more detail at using figures representing only one embodiment preferred of the invention.

Figure 1 is a vertical sectional view of a mechanism according to the invention mounted on a vacuum cutting.

Figure 2 is a vertical sectional view of the mechanism according to the invention in the closed position.

Figure 3 is a vertical sectional view of the mechanism according to the invention at the start of the position opened.

Figure 4 is a vertical sectional view of detail of the mechanism according to the invention in the open position.

Figure 5 is a vertical sectional view of detail of the mechanism according to the invention during the first closing.

Figure 6 is a vertical sectional view of the mechanism according to the invention in the end position first closing.

Figure 7 is a vertical sectional view of the mechanism according to the invention in second position opening.

Figure 8 is a vertical sectional view of the mechanism according to the invention in third position opening.

Figure 9 is a vertical sectional view of the mechanism according to the invention in fourth position opening and locking.

Figure 10 is a vertical sectional view of detail of the sequencing device of the mechanism in accordance with the invention.

Figure 11 is a vertical sectional view of detail of the sequencing device of the mechanism according to the invention during a manual reset.

Figure 12 is a vertical sectional view of detail of the sequencing device of the mechanism according to the invention during an automatic reset.

The actuation mechanism is shown in a way general in Figure 1 where it is mounted on a protective shutdown installed on a power line and to be open to the appearance of a threshold of overcurrent on the line (equal for example to 10 times the nominal current) according to the example shown a vacuum cut-off 1 connected to a first socket 11. The assembly is supported by an isolator 2 on a support structure 3. The movable contact of the vacuum chamber 1 is integral with an operating rod 4 connected to a displacement device 5 driven by a drive member consisting of a helical conductive alloy spring 6 with shape memory (called AMF spring) of an effort by example about 400N and electrically linked to the line by through a braid 7 connecting it by one of its ends at the end of the rod 4. Its heating, when crossed by said overcurrent threshold, is such that said alloy passes from its martensitic phase to its austenitic phase. In the martensitic phase, the spring 6 is relaxed in shape as shown in Figure 1.

The mechanism allows the chamber to be closed cut-off 1 via a sequencing device 8 associated with the displacement device 5 and ensuring a cycle adjustable and timed opening and closing, according to the example represented according to a cycle O-2s-FO-10s-FO-20s-F, and, when the fault remains present, it locks the mechanism in open position.

The mechanism is housed in an envelope 9 which supports a second socket 10 connected by another braid conductive 12 at the other end of the AMF spring 6.

The mechanism and the different phases of this cycle will be described below in more detail.

The displacement device 5 will first of all be described, with reference to Figures 2 and following.

It includes a set of integral and rotating arms around a horizontal axis, one of which 13 is connected to the outlet rod 4 and the other 14 is connected to the AMF spring 6. The arm 13 is connected to the outlet of the rod 4 by a connecting rod 15 pivoting at one of its ends on the arm 13 and at the other of its ends in an oblong hole arrangement 16 and compression spring 17. The oblong hole 16 is made in a piece 18 vertically guided in a guide 19 rigidly fixed to the end of the rod 4 and biased downwards by the compression spring 17. The pivot axis 21 between the arm 13 and the connecting rod 15 is connected to the end of a tension spring 20 of which the other end is fixed at a fixed point. In position of closure, as shown in Figure 2, axis 21 is pulled by tension spring 20 slightly to the left of the vertical axis forming the longitudinal axis of the cut 1 and passing through the axis of rotation of the arms 13 and 14. The pivot 22 is then pushed at the top of the oblong hole 16. In this position, the connecting rod 15 is in abutment against a fixed stop piece 32.

The other arm 14 is connected at its end to the free end of a rod 23 sliding inside the AMF spring 6 and carries a roller 24 and a hook 34 pivoting on a horizontal axis all cooperating two with the sequencing device 8 as will be seen more far. The rod 23 carries at its inner end to the spring AMF 6 a stop 25 engaged with an end piece 26 secured to the AMF spring 6. The other end of the spring 6 is connected to a fixed support part 27.

This device forms a snap action mechanism on either side of the dead center formed by the vertical axis forming the longitudinal axis of the breaking chamber 1 and passing through the axis of rotation of the arms 13 and 14 and, in the first position shown in Figure 2, it pushes the movable contact of the breaking chamber 1 in position closed. The stop piece 32 is adjustable and allows calibrate the opening force.

A third arm 28 is integral with arms 13 and 14. It is connected to a piston rod 29 which is stressed by a return spring 29A and which slides in a fixed cylindrical chamber 30 supplied with gas, preferably air, in a closed circuit by a bellows arrangement or equivalent compresses gas in a compression volume 31 provided in the housing 9 via a valve non-return 30A. The function of this piston 29 and of this compression chamber 30 will appear later in the description.

When a fault current and a exceeding the overcurrent threshold, the AMF 6 spring passes at its austenitic phase and takes its compressed form as shown in Figure 3. It therefore pulls the rod 23 by its end stop 25 and thereby turns the arms united 13, 14 and 28 against the force of the spring until the connecting rod 15 and / or the arm 13 comes into abutment against a second fixed abutment piece 33. During this movement, the pivot 22 moves in the hole oblong 16 and the spring 17 is decompressed. It is so achieved an accelerated movement thanks to the inertia of the masses moving. The stop 33 is preferably made of a shape memory and converts kinetic energy into heat, thus minimizing the rebound effects of contact mobile from chamber 1. Thanks to kinetic energy accumulated, moving the moving contact and opening of the breaking chamber 1 are then produced at a speed relatively high instantaneous, for example of the order of 1 m / s. Thanks to the neutral mechanism with push spring 17, a maximum opening speed is guaranteed at the appearance of the overcurrent threshold, and the heating of the AMF 6 spring is thus of limited duration.

Room 1 being open, the line current is cut and the AMF 6 spring cools down until it resumes relaxed shape as shown in figure 4.

The sequencing device 8 then comes into action.

As can be seen in the figures, this device sequencer 8 has three retractable cams 81, 82, 83 and two non-retractable end locking cams stroke 84, 85 aligned on a rotating wheel subjected to a return spring not shown, the action of which tends to drive the wheel in the direction of arrow F. A hook 86 pivoting on a fixed axis retains one of these cams against the action of the return spring.

The first three cams 81, 82, 83 are each retractable by means of a time delay consisting of a pneumatic cylinder 87, 88, 89 as it will be specified later.

In the closed position shown in Figure 2, on the first cam 81 are engaged in traction the hook 34 of the rod 23 and the fixed hook 86 and in pushing engagement roller 24 of rod 23.

When compressing the AMF 6 spring and the opening of chamber 1, as shown in the figure 3, the rod 23 is pulled by this spring 6 and the hook 34 pulls on the first cam 81 turning the wheel of the sequencing device in the opposite direction to arrow F. The fixed hook 86 then engages the second cam 82, keeping the wheel in this second position.

Once the AMF spring has been extended, as shown in Figure 4, the spring 20 tends to rotate the arm 14 in the direction of arrow F but this is blocked by the thrust stop of the roller 24 against the first cam 81 retained by the cylinder 87. This cylinder has an orifice air outlet calibrated to delay the retraction of the cam 81 according to a time lapse of for example 2 seconds.

This situation is shown in detail on the Figure 5. After said time, the cylinder 87 releases the cam 81 which retracts towards the inside of the wheel pivoting around axis 81A. The roller 24 therefore passes this first cam 81, the arm 14 being rotated by the action of spring 20. The rotation then continues until that the bialle 15 comes to bear on the stop 32 and the hook 34 hooks onto cam 82, as shown in figure 6.

In the position of Figure 6 thus reached, the supportive arms 14, 13, 28 have returned to their position initial and the movable contact of chamber 1 is pushed back in the closed position firstly and secondly time thanks to the kinetic energy accumulated the spring 17 is recompressed and the neutral point is refilled by the device 5. The first timed reclosing is thus carried out.

The AMF 6 spring is therefore again connected to the line and if the fault current is still present, it resumes heating and changes shape and phase previously described opening starts again as shown in FIG. 7. This time, it is the second cam 82 which is pulled by the hook of the rod 34. The fixed hook 86 engages the third cam 83. When AMF 6 spring cooling, this is the cylinder timer 88 having an air exhaust port set for example to 10 seconds, which regulates the retraction of cam 82 and return to the closed position of the chamber 1.

If the fault current is still present, the phases open and close again in the same way, the opening phase being represented in FIG. 8. The third cam 83 is now moved and the cylinder 89 which delays its retraction to for example 20 seconds, for reclosing, the fixed hook 86 retaining the fourth non-retractable cam 84.

If the fault current is still present, then a the opening and locking phase. The sentence is identical to the previous ones, but once the AMF 6 spring cooled and returned to its relaxed position, as shown in Figure 9, the cam 84 not retractable blocks roller 24 and the mechanism is locked in chamber opening position 1.

In the previously described case where the current of fault resulted in four opening phases, the mechanism is therefore locked and resetting takes place manually. To do this, as shown in Figure 10, the cams are linked to a disc 90 secured to a pole 91. This disc 90 is rotating on the same horizontal axis as the wheel supporting the cams 81 to 85. These are supported with pivoting 81A to 85A at the end of spokes of this wheel with an intermediate joint 81B to 85B connected to disk 90. More precisely, each fixed radius 81C to 85C of the wheel supports an arm at its end intermediate support 81D to 85D with pivoting along an axis horizontal and it's at the end of this intermediate arm that is pivotally connected to each cam. In position of operation, the intermediate arms 81D to 83D are retained in alignment with fixed spokes 81C to 83C thanks to the thrust of the timing cylinders 87 to 89, the rod is connected to the end of the retractable cams 81 to 83 opposite to that pivoting around the axes 81A to 83A. The locking cams 84 and 85 are retained with pivoting at their free end on a fixed support not shown.

When the operator pulls down the pole 91 as shown in figure 11, so it rotates according to arrow F1 the disc 90 and therefore the joints 81B to 85B linked to it. The arms 81D to 85D are therefore moved towards the inside of the wheel and the cams 81 to 85 are deleted, releasing the fixed hook 86, the hook 34 and the roller 24. The displacement device is released is closes chamber 1 and the return spring urging the cam support wheel brings it back according to arrow F in original position shown in Figure 2.

In the event that the fault current disappears during the progress of the phases described above, during the next closing phase, the AMF 6 spring is no longer crossed by an overcurrent and therefore no longer takes its form compressed and chamber 1 remains closed. The line is then during normal operation and the device must be reset sequencer alone to return to the original position shown in Figure 2. The mechanism includes a automatic reset arrangement for this surgery.

This arrangement includes the piston 29 already described. In sliding in the fixed cylindrical chamber 30, it compresses gas in compression volume 31. This compression has place each time room 1 is opened. delay slightly higher than the total time of timed sequences produced by a 92A pilot valve by a pneumatic timer 92B and connected by a hose on the one hand to the compression volume 31 and on the other hand to a cylinder 92, this compressed gas supplies this cylinder 92 visible on Figure 10. This cylinder 92 is fixed on the disc 90 and its rod is linked to the cam support wheel 81 to 85. Powered under pressure, this jack 92 rotates the support wheel and the cams 81 to 83 are. displaced inward, as shown in Figure 12, the joints 81B to 83B being slid in oblong openings 81E to 83E arranged in the disc 90. The hooks 34, 86 and the roller 24 are thus released and the sequencer wheel returns to the original position by the action of its spring reminder. A spring 93 then brings the cams back into position active.

It should be noted that this automatic deletion is only provide that for the three retractable cams 81 to 83 as visible in Figure 12, since the cycle is interrupted before locking by the last two cams 84 and 85. The support wheel advantageously is therefore formed of two separate parts one bearing the three cams retractable 81 to 83 and the other carrying the two cams lock 84 and 85, the reset arrangement automatic only for the first three cams 81 to 83.

Claims (8)

1. An actuating mechanism for actuating the moving contact of a protective interrupting chamber (1) which is installed on a high-voltage or medium-voltage power line and which is to be opened when a current in excess of a surge current threshold flows through line, the mechanism including a drive member for driving a displacement device (5) for displacing the contact, said drive member being a conductive helical spring (6) made of a shape memory alloy and electrically coupled to the line, a current in excess of said surge current threshold passing through the spring heating said spring to such an extent that said alloy goes from its martensitic phase to its austenitic phase, said mechanism being characterized in that the mechanism enables the interrupting chamber (1) to be re-closed by means of a sequencer device (8) associated with the displacement device (5), and providing an adjustable and timed opening and closing cycle.
2. An actuating mechanism according to claim 1, characterized in that the displacement device (5) is a snap-acting mechanism toggling on either side of a dead center, it is connected to the moving contact, and it is displaceable from a first position, in which it pushes the contact to the closed position, to a second position in which it pulls the contact to the open position under the effect of the spring (6) made of a shape memory alloy being compressed, which spring is connected at one of its ends to a fixed support portion (27), and at its other end to the displacement device (5) via a rod (23) mounted to slide inside the spring (6) and coming into abutment at said other end when the spring (6) is relaxed.
3. An actuating mechanism according to claim 2, characterized in that the displacement device (5) includes two arms (13, 14) comprising a single part that is mounted to rotate about an axis, a first one of the arms (13) being urged to rotate by a traction spring (20) and being connected to the moving contact via a pivotally-mounted connection rod (15), and via a unit comprising a guided part (18) that is guided in a guide (19) rigidly connected to the contact, which guided part is urged by a compression spring (17) and is provided with an oblong hole (16) along which the pivot pin (22) of the connection rod (15) can slide, and the second arm (14) being secured to the slidably-mounted rod (23).
4. An actuating mechanism according to claim 2, characterized in that the sequencer device (8) includes at least one retractable cam (81, 82, 83) that is retractable via time-delay means (87, 88, 89), against which cam a catch (34) fixed to the free end of the slidably-mounted rod (23) is engaged in traction, and against which cam a roller (24) also fixed to the free end of the slidably-mounted rod (23) is engaged in thrust.
5. An actuating mechanism according to claim 4, characterized in that the sequencer device (8) includes a plurality of retractable cams (81, 82, 83) lined up around a rotary wheel subjected to a return spring, and a catch (86) mounted to pivot about a fixed axis and retaining one of the cams against the action of the return spring.
6. An actuating mechanism according to claim 5, characterized in that the sequencer device (8) also includes two non-retractable end-of-stroke locking cams (84, 85).
7. An actuating mechanism according to claim 6, characterized in that the sequencer device (8) includes independent means for manually disengaging all of the cams so as to reset the mechanism at the end of a cycle.
8. An actuating mechanism according to claim 6 or 7, characterized in that the sequencer device (8) includes independent means for automatically disengaging the cams so as to reset the mechanism during a cycle, which means comprise a pneumatic actuator (92) fed with gas via a valve (92A) controlled by a pneumatic time-delay member (92B), via a compression chamber (31) in which a piston (29) coupled to the displacement device (5) is slidably mounted.

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