FR2472257A1 - Gas blast interrupter - has spring biassed piston drawn back during first opening phase and released to provide air blast to extinguish arc. - Google Patents

Abstract

The gas blast interrupter comprises an insulator cylinder containing a coaxial tube carrying at its lower end a piston formed by a radial flange and sealing diaphragm. The upper end of the tube carries a nozzle surrounding an internal semi-fixed arcing contact engaged through the nozzle by a mobile arcing contact which snap engages through the nozzle. The mobile contact is carried by an arm which serves as a main contact engaging a fixed main contact on the upper cylinder. Raising the arm disengages the main contacts while the mobile contact raises the piston against a biassing coaxial spring. Towards the end of its stroke the mobile contact disengages from the nozzle and the spring rapidly drives the piston down forcing air through the tube and out the nozzle to extinguish the arc between the arcing contacts.

Description

Disconnector cut-off under load with pneumatic blowing of the arc.

The invention relates to a disconnector with cut-off under load with pneumatic blowing of the arc comprising - a movable arcing contact carried by a movable support, - a semi-fixed arcing contact capable of cooperating with the contact of movable arc in the closed position, - a blowing nozzle coaxially surrounding said contacts in the closed position of the latter, - a blowing assembly with pistonable volume, confined by a piston and a cylinder and communicating immediately with the interior of the nozzle to allow a direct escape of the gas, compressed by the relative movement of the piston with respect to the cylinder, towards the cut-off zone to blow the arc drawn during the separation of the contacts, - a movable assembly formed by the movable element of the blowing assembly and the semi-fixed contact capable of moving against a restoring force to accompany the moving circ contact over a limited stroke in its movement in the direction of opening of the secti onneur, - a temporary retaining means provided between the moving element and the moving contact for mechanically joining the latter during said limited stroke, said contacts being closed, and for releasing said said moving element after said limited stroke, the latter being returned to position rest by the restoring force, said separating contacts and the blowing assembly causing a blowing of the arc drawn between the separated contacts.

A disconnector of the kind mentioned, commercially known
Fuc and described in French patent NO 2,078,520, gives complete satisfaction and is capable of cutting large nominal currents thanks to the combined action of the pneumatic blowing of the arc and the rapid separation of the contacts. The compression energy of the blowing gas is derived from the opening movement of the disconnector, which considerably simplifies the structure of the device. During the breaking of small inductive currents, the large blowing of the arc causes a sudden interruption of the current generating a transient voltage. high recovery which may cause late breakdown. The object of the present invention is to remedy these drawbacks without any significant complication of the device and without modifying the breaking characteristics of large currents.

The load disconnector according to the present invention is characterized in that said blowing assembly comprises gas exhaust means arranged to reduce or prevent compression of the gas in said pistonable volume and blowing of the arc during the first phase the return stroke of the moving part, so as to delay the blowing of the arc and allow rapid acceleration of the moving part.

During the first phase of displacement of the blowing piston under the action of the return spring, the compressed gas escapes freely towards areas far from the arc.

The arc is blown at its normal rate only at the end of this first phase and the arc is interrupted gradually, reducing the recovery voltage.

The breaking of the capacitive currents is also improved, a reclapling taking place immediately on the initial oscillation.

The free escape of gases at the start of the contact opening stroke has the advantage of rapid acceleration of the contact, the piston not being braked by the compression of the blowing gases in the cylinder. This rapid acceleration, combined with the inertia effect of the moving assembly, makes it possible to preserve the breaking characteristics of large currents, which are not modified.
notably by reducing the active stroke
age. The exhaust of the gases during the first phase of opening or of the contacts can be carried out through orifices
swam in the cylinder wall, or according to a mode of placing
preferred work, by means of communication between
the cylinder chambers delimited by the piston.
means of communication can be realized by rai
nures formed in the inner wall of the cylinder, the
which grooves extend over a portion of the height
of the cylinder corresponding to the time delay phase of the
blowing. The number and the section of the grooves are chosen.
located so as to avoid any appreciable escape of gas towards
the cut-off zone.

The height of the grooves or generally the phase
blowing delay corresponds substantially to the
third of the displacement piston displacement stroke,
but it is clear that this length as well as the section
exhaust gases must be adapted to the type of inter
breaker or disconnector.

The disconnector known according to the aforementioned patent includes a
movable contact with bulged end snap-in
in a tulip-shaped contact. Darcarc as contacts
knew the double function of electrical contact and worm
temporary mechanical rusting, which complicates their struc
and may be the source of malfunctions.

Another object of the invention is to remedy this drawback
deny and give the arcing contacts a single function,
in this case the electrical function.

Other advantages and features will emerge more
clearly from the following presentation of a mode of implementation
work of the invention, given by way of nonlimited example
tif and shown in the accompanying drawings, in which
Figure 1 is a side view of a disconnector according to the invention; Figure 2 is an enlarged view of the disconnector self-blowing device according to Figure 1, shown in the open position of the contacts; Figure 3 is a view similar to that of Figure 2 showing the cut-off device at the time of contact separation; Figure 4 is a sectional view on an enlarged scale of the contact device in the closed position of an alternative embodiment according to the invention.

Figures 1 and 2, which correspond to the figures of the aforementioned French patent NO 2,078,520, we recognize: the base 1 and the insulators 2 and 3 respectively carrying a connection terminal 4 and a fixed main contact 5 with contact tab 9 , capable of cooperating with a movable main contact 8, carried by a knife 6, articulated at 7 on the terminal 4. The knife 6 is controlled by the rotation of a shaft 10 carrying a crank 11 cooperating with a control rod 12. The knife 6 carries a movable arcing contact 13 capable of cooperating with a contact tulip 14 constituting a semi-fixed contact. Referring more particularly to FIG. 2, representing the upper part of the insulator 3, it can be seen that the semi-fixed contact 14 is carried by a tubular rod 15 ending in a piston 20 with a sealing membrane 21 fixed by a washer 22 and a circlip -23. The semi-fixed contact 14 is disposed inside a blowing nozzle 17 fixed to the tubular rod 15. The movable assembly constituted by the semi-fixed contact 14, the nozzle 17, the tubular rod 15 and the piston 20, is capable of sliding in a cylindrical recess 16 of the insulator 3. The movable arcing contact 13 carries at its end a bulge 25 capable of snapping into the tulip-shaped arcing contact 14 to produce a temporary locking. A spring 24 biases the piston 20 and the associated moving element 15, 14, 17 in the lowered position in FIG. 2. When the disconnector 6 opens, the contact 13 snapped into the tulip 14 causes the moving element to move 14, 15,17,20 by compressing the spring 24. After opening the main contacts 8, 9 and coming to the end of the movement of the moving assembly 14, 15, 17, 20, the contact 13 escapes from the tulip 24 by drawing a bow. The released moving element suddenly moves in the opposite direction under the action of the spring 24 by compressing the gas in the cylinder 16. The compressed gas escapes through the conduit 15 towards the cutting zone surrounded by the nozzle 17 and blows l 'bow. Such a disconnector and its operation are described in detail in the aforementioned patent to which reference will advantageously be made for further details.

According to the present invention, grooves 26 are formed in the. inner wall of the cylinder 16. These grooves, arranged in the upper part of the cylinder 16, extend over a height close to one third of the active stroke of the piston 20. The grooves 26 may extend along generatrices of the cylinder 16 in being distributed circumferentially, and these grooves may have sections of various dimensions. It is easy to see that in the high position of the movable assembly 14, 15, 17, 20, the two chambers delimited by the piston 20 inside the cylinder 16, communicate via the grooves 26.

This communication remains during the first phase of the opening stroke, in this case at the start of the return movement of the moving assembly downwards until the piston 20 crosses the bottom of the grooves 26. During this first phase, the piston gas is discharged through the grooves 26 towards the upper part of the cylinder 16 without appreciable blowing through the nozzle 17. After crossing the grooves 26, the piston gas escapes entirely by the tubular rod 15 towards the cutting zone, so as to blow the arc as described in the aforementioned patent. The grooves 26 make it possible to obtain a delay in the blowing of the arc, favorable to the extinction of low inductive or capacitive currents. The mobile assembly 14, 15, 17, 20 is not braked during the first phase of displacement by the compression of the gases in the cylinder 16 and its speed of movement is thus increased. The gas piston effect during the second opening phase is increased, and it has been observed that the performance of the disconnector is practically unaffected by the presence of the grooves 26 for breaking the large currents.

Figure 3 illustrates an alternative embodiment, using orifices 27 formed in the side wall of the cylinder 16 in the upper part of the latter. It is clear that the gas compressed by the displacement of the piston 20 escapes freely towards the outside through the orifices 27 until the piston 20 has not crossed the lowest orifice 27.

The delay effect of the blowing without braking of the movement of the movable assembly is also obtained in this variant embodiment, and other embodiments can be designed, in particular valve systems or the like, provided in the cylinder 16 or the piston. 20.

If the moving element 14, 15, 17, 20 is guided in its movement by independent means, it is possible to shorten the cylinder 16 to allow the piston 20 to exit from this cylinder 16. In this case, the blowing effect intervenes after the first phase of opening the disconnector when the piston 20 enters the cylinder 16.

Referring to Figure 4, which illustrates an alternative embodiment, it can be seen that the movable arcing contact 13 has a cylindrical end which fits in the closed position in the tulip arcing contact 14. The nozzle 17 has on its outer periphery an annular groove 28, in which are snapped two coil springs 29, 30 integral with the knife 6 in the closed position of the arcing contacts.

The frustoconical shape of the front part of the nozzle 17 facilitates the deformation of the springs 29, 30 and their snap-fastening in the groove 28. It is easy to see that when the knife 6 pivots towards the open position, the springs 29, 30 cause the nozzle 17 and the associated mobile assembly to move in their movement, until the piston 20 reaches the end of its travel, the arcing contacts 13, 14 remaining swollen. Continued movement of the knife 6 causes the springs 29, 30 to spring out of the groove 28 with a chamfered edge by elastic deformation and breaks the connection between the knife 6 and the moving element 17, 20, 14. The latter released is suddenly recalled towards the rest position as described above. The arcing contacts 13, 14 separate posteriorly ~ at the exit of the springs 29, 30 from the groove 28 and the drawn arc is blown by the compressed gas.

The springs 29, 30 allow limited pivoting of the knife 6 relative to the nozzle 17, but it is clear that these springs could be of a different type, for example with a blade, or that the attachment of the knife 6, nozzle 17 can be done in a different way. The arcing contacts 13, 14 are freed from any release force.

The invention is of course in no way limited to the mode of implementation described and it extends to any variant remaining within the framework of equivalence, in particular to that in which the cylinder would be movable and the piston fixed, or that in which the disconnector would have a sliding main contact.

Claims (10)

Claims 1. Disconnector cut-off under load with pneumatic arc blowing comprising - a movable arcing contact (13) carried by a movable support, - a semi-fixed arcing contact (14) capable of cooperating with the contact arc (13) movable in the closed position, - a blowing nozzle (17) coaxially surrounding said contacts (13, 14) in the closed position of the latter, - a blowing assembly with pistonable volume, confined by a piston (20) and a cylinder (16) and immediately communicating with the interior of the nozzle (17) to allow direct escape of the compressed gas by the relative movement of the piston (20) relative to the cylinder (16) towards the area of cut to blow the arc drawn during the separation of the contacts (13, 14), - a movable assembly (14, 20) formed by the movable element (20) of the blowing assembly and the semi-fixed contact ( 14) and capable of moving against a restoring force (24) to accompany the movable contact (1 3) in its movement in the opening direction of the disconnector, - a temporary retention means provided between the movable assembly (14, 20) and the movable contact (13), for mechanically joining the latter during said limited stroke, said contacts (13, 14) being closed, and to release after said limited stroke said movable assembly (14, 20), the latter being returned to the rest position by the return force (24), said contacts (13, 14) separating and the blowing assembly (16, 20) generating a blowing of the arc drawn between the separate contacts (13, 14), characterized in that said blowing assembly (16, 20) comprises exhaust means of gases arranged to decrease or prevent compression of the gas in said pistonable volume and blowing of the arc during the first phase of the return stroke of the moving assembly (14, 20}, so as to delay the blowing of the arc and allow rapid acceleration of the moving assembly (14, 20). 2. Disconnector according to claim 1, characterized in that said first phase of the return stroke corresponds substantially to one third of the return stroke of the moving assembly. 3. Disconnector according to claim 1 or 2, characterized in that said exhaust means comprise means of communication between the two chambers of the cylinder (16) separated by the piston (20). 4. Disconnector according to claim 3, characterized by one or more grooves (26) of communication formed in the internal wall of the cylinder (16) over a height corresponding to said first phase of the return stroke. 5. Disconnector according to claim 1 or 2, characterized in that said exhaust means consist of orifices (27) formed in the wall of the cylinder (16) to allow the escape of gas to the outside of the cylinder. 6. Disconnector according to any one of the preceding claims, comprising a fixed cylinder (16), a movable piston (20), integral with a semi-fixed contact (14) in the form of a tulip, a nozzle (17) integral with the semi-fixed contact (14) a movable contact (13) engaged in the tulip (14) during said limited stroke, the separation of the contacts (13, 14) taking place by elastic deformation of the tulip (14) at the end of the stroke of the piston (20) in the cylinder (16), characterized in that the cylinder (16) has on its internal face grooves (26) extending over part of the height of the cylinder disposed on the side of the movable contact ( 13). 7. Disconnector according to claim 6, characterized in that the movable contact (16) is subject to the end of a knife (6) capable of cooperating with a fixed main contact (9) carried by said cylinder (16) . 8. Cut-off disconnector under load comprising - a pivoting knife (6) carrying at its end a movable main contact and a movable arcing contact (13) in the form of a rod, - a fixed main contact (9) carried by a support insulator (3) with end formed in a blowing cylinder (16), - a movable assembly comprising a blowing piston (20) cooperating with the cylinder (16), a semi-fixed arcing contact (14) and a nozzle ( 17) coaxially surrounding the arcing contacts (13, 14) in the closed position, - a return spring (24) biasing the moving element in the rest position, characterized in that a hooking means (28, 2930) secures in the closed position of the arcing contacts (13, 14) the knife (6) and the nozzle (17), so that the mobile assembly (20, 14, 17) accompanies the knife (6) during a first phase of the opening stroke, the arcing contacts (13, 14) remaining closed and that said latching means (28, 29, 30) is released automatically at the end of said first re phase to allow the moving equipment (28, 29, 30) to return to the rest position with separation of the arcing contacts (13, 14) and blowing of the drawn arc between the arcing contacts (13, 14). 9. Disconnector according to claim 8, characterized in that said cylinder (16) has gas exhaust means according to any one of claims 1 to 7. 10. Disconnector according to claim 8 or 9, characterized in that said attachment means comprises a groove (30) formed on the outer periphery of the nozzle (17) and at least one spring (29, 30) carried by the knife (6) and capable of snapping into the groove (30) to secure the knife (6) and the nozzle (17).