FR2526998A1 - ROTATING ARC SWITCH AND PERMANENT MAGNET - Google Patents

Abstract

THE INVENTION RELATES TO A PERMANENT MAGNET ARC EXTINGUISHING DEVICE. THE FIXED CONTACT 18 IS PROVIDED INSIDE THE PERMANENT 22 ANNULAR MAGNET WITH AXIAL MAGNETS GENERATING THE ROTATION OF THE ARC. THE CURRENT SUPPLY TO THE FIXED CONTACT 18 IS CARRIED OUT THROUGH A CIRCUIT 26 INCLUDING AN INTERNAL VIROLE 32 AND A TUBE 44 FIXED CONTACT SUPPORT 18. THE REVERSE CIRCULATION OF CURRENT IN FERRULE 32 AND TUBE 44 MET MAGNET 22 SAFE FROM ANY FIELD OF DEMAGNETIZATION. APPLICATION: CUTTING OF DC OR ALTERNATIVE CURRENTS IN SWITCHES OR CIRCUIT BREAKERS FOR MEDIUM OR LOW VOLTAGE NETWORKS.

Description

ROTATING ARC SWITCH AND PERMANENT MAGNET.

  The invention relates to a rotary arc switch or circuit breaker comprising a sealed envelope filled with insulating gas of high dielectric strength, a pair of separable contacts, a permanent magnet generating a magnetic field in

  the area of contact separation to impose a rotation

  arc, a pair of connection pads and an electrical connection with said contacts, and a current supply circuit arranged between each antenna and the corresponding contact, and comprising a first

  current path outside the magnet.

  European patent application NI 37,765 relates to such a

  switch, and the permanent magnet is arranged in the

  The current flowing through the fixed contact and the supply circuit does not pass through the permanent magnet and does not generate any magnetic field capable of demagnetizing the magnet.

  housed inside the fixed contact.

  According to the German patent application AS 1 236 628,

  rotary arc interrupter comprises two annular permanent magnets with radial magnetization and coaxially surrounding the separable contacts The current flow in the contacts causes a demagnetizing magnetic field inside each magnet This results in a risk of

  demagnetization of permanent magnets which depends on the inp-

  voltage of the current flowing in the switch and the magnetic material of the magnet This type of switch is mainly used for breaking currents of low currents, but it is unable to cut

  high currents, for example, greater than 15 kA.

  to demagnetize the magnet, we have already

  proposed in accordance with FIG. 4 of US Patent 3,082,307, of which

  the annular magnet traversed by the fixed contact, by means of a copper manchen screen The flux, generated by the passage of the current in the contact, induces eddy currents in the protective sleeve of the magnet The result is an antagonistic flow that opposes

  degaussing flow This device does not give full

  tisfaction, and the risk of demagnetization of the sub-

  especially on the cutting of continuous currents.

  The present invention aims to enable the realization of

  a reliable contact switch arranged inside the

  permanent magnet, the latter being protected from any field of demagnetization regardless of the intensity

current to interrupt.

  The switch according to the invention is characterized in that the permanent magnet surrounds one of the contacts, and

  that the latter is electrically connected to the first

  external jet of the supply circuit by a second path

  dull shaped to avoid any demagnetization field inside the hollow space of the magnet The second path of the current supply circuit has a flange

  U-shaped with a hairpin section extending along the inner face

  dull of the permanent magnet, the circulation of the current being effected in the opposite direction in the branches substantially parallel to the pin It follows that inside the magnet, the magnetic fields generated by the passage of the current in the branches of the U compensate themselves, without any

  risk of demagnetization of the permanent magnet.

  By using an annular permanent magnet, the second current path is advantageously formed by an inner ferrule whose one end is connected to the first external path and whose opposite end is connected to a tube or sleeve for supporting the contact. inner ferrule being arranged coaxially between the magnet and the tube or sleeve. One of the contacts surrounded by a first permanent magnet

  can be fi-xed and has an annular end of

  tact arranged in the vicinity (projecting or withdrawing) from the front front face of the magnet This contact can also be semi-fixed by being connected to the inner ferrule by means of a sliding contact or a clamp

of contact.

  The other movable contact in translation passes axially

  a second permanent magnet and is connected

  to the corresponding inner shell of the circuit by a

  sliding contact, the second magnet being arranged

  the first magnet and separated from the latter by a

predetermined axial length.

  The magnetization of the permanent magnet (s) may be

  concave, either homopolar radial or axial, or heterogeneous

  The shell is filled with an electronegative gas

  such as sulfur hexafluoride, and according to a

  of the invention, the magnetic blowing of the arc by the action of the permanent magnet (s) is combined

  pneumatic blowing by selfexpansion of gas

  awarded by the hollow contacts.

  Other advantages and features of the present invention

  will come out more clearly from the following description

  various embodiments, given by way of nonlimiting example and represented in the accompanying drawing in which Figure 1 is a partial schematic view in axial section of a rotary arc switch according to the invention, shown in position of closing on the right half-view, and in the cut-off position on the left half-view; Figure 2 is a partial view, similar to that of Figure 1 of an alternative embodiment;

  Figure 3 shows an axial sectional view of another embodiment.

  In FIG. 1, a pole of a switch 10 or a switch

  rotating arc junction has a sealed envelope 12

  made of insulating molded material, filled with gas insulating

  high dielectric strength, especially sulfur hexafluoride The cylindrical casing 12 has an elongated shape whose upper part is closed by a bottom 14 made of conductive material and with a radial flange shaped into a current supply zone 1 E inside the casing 12 are arranged axially a fixed contact 18 cooperating with a movable contact 20 aligned and axially slidably mounted

  by means of an actuating rod of a mechanism

  control unit (not shown).

  The fixed contact 18 in the form of hollow cylinder with a diameter

  equivalent to that of the movable contact 20, is surrounded by

  axially by a permanent magnet 22 annular and fixed.

  The permanent magnet 22 with radial magnetization generates in

  the arc zone a permanent radial magnetic field

  the rotation of the arc during the separation of

  tacts 18, 20 The end of the fixed contact 18 lying

  abutting with the movable contact 20 in the iron position

  3, a protrusion circuit 26 supplies the electrical connection of the fixed contact 18 with a

  central stud 28 of conductive material secured to the bottom 14-.

  The circuit 26 for supplying current to the fixed contact 18 tubular

  laire is formed by an annular conductive carcass of revolution about the longitudinal axis and having a

  The recess 30 for housing the permanent magnet 22.

  circuit breaker 26 is shaped in a loop surrounding the

  four faces of the annular permanent magnet 22, and

  carries a conductive copper base with a U section

  killed by way of example by assembling two ferrules

  internal coaxial 32 and outer 34 to a washer 36 annul-

  hairsheet 11 front face 24 front of the magnet 22 The outer shell 34 is connected to the central pad 28 by a conductive ring 38 extending parallel to the

  front end face 40 of the magnet 22 with interpolation

  The ferrule 32, isolated from the ring 38 and the stud 28, is secured to a tube 44 supporting the fixed contact forming an annular flange 45 having an upside-down U-shaped section, said flange 45 being housed in the cylindrical internal space of the permanent magnet 22. The inner ferrule 32 is interposed coaxially between the cylindrical lateral face.

  46 of the magnet 22 and the tube 44 made of metal material

  particularly copper or steel.

  A thin sleeve (not shown) of insulating material can

  be inserted axially into the radial gap 48 of the re-

  edge 45 reversed The current supply circuit 26 to the con-

  fixed tact 18 forms with the permanent magnet 22 and the stud 28

  a monobloc assembly carried by the bottom 14 The permanent magnet

  22 is constituted by a ferrite magnet or a metal magnet, and an insulating layer (not shown) can

  be inserted between the magnet 22 and the conductive carcass

ring circuit 26.

  Note that the current supply circuit 26 to the con-

  fixed tact 18 has a first path outside the

  the magnet, connected in series with a second trjet to the in-

  of the annular magnet 22 The first path

  takes the ring 38, the outer ring 34 and the washer 36 which respectively cover the plate 42 of the face

  posterior head 40, the cylindrical lateral face ex-

  dull 50, and the front end 24 of the magnet

  The second path includes the rim 45

  poured formed by the inner ferrule 32 associated with the tube 44

fixed contact support 18.

  The switch according to FIG. 1 operates in the following manner. In the closed position of the switch, represented on the right half-section of FIG. 1, the current returns through the range 16 associated with the bottom 14 and flows in the stud 28. and the supply circuit 26 to the fixed contact 18 according to the direction indicated by the arrows The path to pzrtir the central stud 28 is as follows: ring 38, outer ring 34, washer 36, inner ring 32, tube 44, fixed contact 18 and movable contact 20 abutting.

  The current flowing through the ring 38, ferrule 34 and the rim

  delle 36 of the first external path does not cross the magnet

  ring and does not generate any magnetic field.

  The ferrule 32 and the tube 44 of the second internal path are separated by the small radial gap 48 and are traversed by

  opposite axial direction by the current.

  thought of magnetic fields generated in space

  internal cylinder of the magnet 22 by the passage of the neck.

  The permanent magnet is thus protected from any degaussing field,

  even in the presence of strong short-circuit currents

  The permanent magnet 22 generates a magnetic field permanently present in the breaking zone as soon as the contacts 18, 20 are separated. The switch is opened by

  sliding down of the movable contact 20 (see half

  left section of fig 1), and the arc drawn between the

  tacts 18, 20 extends substantially in the axial direction.

  The magnetic field of the permanent magnet 22 causes in a well-known manner the rotation of the arc on the annular tracks of the contacts 18, 20 hollow It should be noted that the axial projection of the fixed contact 18 with respect to

  the washer 36 of the conductive carcass ensures the hand-

  of the arc roots on the annular tracks of

tacts 18, 20.

  FIG. 2 shows an alternative embodiment in which the axial length of the tube 4 t-t support of the xed contact 18 is shortened so as to position the fixed contact 18 in recess or in the vicinity of the washer 36.

  closing position, the passage of the current in the cir-

  cooked supply 26 is identical to that of the device of the

  fig 1, and no degaussing field affects the

  the permanent magnet 22 is fed through the axial path of the current in and through the ferrule 32 and the tube 44. At the beginning of the opening stroke of the contacts 18, 20 the switching of the arc of the fixed contact takes place 18 to the washer 36, which then plays the role of annular track of migration of the rotating arc After switching, the

  current flows only in the first path of the cir-

  The arc rotates in the SF 6 gas under the action of

  magnet field around the washer 36 and the end

  Annular mite of the movable contact 20, the inner ferrule 32

  and the tube 44 is not traversed by any current.

  FIG. 3 illustrates another variant embodiment in which the same reference numerals are used to designate parts that are identical or similar to those of FIGS. 1 and 2. The magnetic blow molding by rotation of the arc is accompanied by a double pneumatic blowing due to

  the thermal expansion of the gas generating a flow of

  Zeux escaping through the fixed tubular contacts 18 and mobile 20 The breaking chamber 54 of the switch 10

  is separated from the casing 12 by an intermediate casing 56

  diary consisting of a cylindrical wall coaxial with the

  veloppe 12, and transverse bulkheads 58, 60

  The insulating upper partition 58 is traversed axially by the fixed pin 28 of tubular shape and with radial opening 62 formed between the bottom 14 and the partition.

  58 The movable contact 20 is secured to a sleeve 63 con-

  ductor mounted to slide axially through an orifice of the lower partition 60, said sleeve 63 actuated by means of a control rod 64 sealingly traversing the bottom 66 connected to a conductor connecting strip 68 The sleeve 63 comprises openings 70

  radial arrangements arranged between the partition 60 and the bottom 66.

  The fixed contact 18 is surrounded inside the breaking chamber 54 by the permanent magnet 22 and the annular circuit 26 current supply as described with reference

  in fig 1 The arc turning under the action of the field of -

  the magnet 22 causes in a well known manner the increase in pressure of the gas inside the breaking chamber

  54 This results in a gaseous flow that favors the ex-

  arc tinction, the gas escaping to the envelope 12 in opposite directions respectively through the fixed tubular contact 18 and the opening 62 of the

  28, and through the movable contact 20 and open them.

70 of the sleeve 63.

  The magnetic blowing of the arc can be reinforced by using

  reading in the device of Fig 3 a second permanent magnet 72 coaxially surrounding the movable contact 20 to

  inside the breaking chamber 54, and arranged in

  keeping the first permanent magnet 22 associated with the contact

  fixed 18 The second magnet 72 is fixed and separate -axial-

  first magnet 22 by a predetermined interval substantially corresponding to the axial length of the zone

  The moving contact 20 passes through the second

  permanent mantle 72 annular, and is electrically connected

  at the bottom 66 of the connection range 68 via

  The connecting circuit 74 is similar to the contact 26 for supplying current to the contact with a contact circuit 74 arranged to avoid degaussing the magnet.

  fixed 1 &, and has a sliding contact 76 arranged at the

  vane of the partition 60 between the sliding sleeve 63 and a conductive bushing 75 coaxial The inside diameter

  of the bushing 76 corresponds substantially to the outside diameter

  The sleeve 78 extends along the inner side face of the magnet 72 and is electrically to a surrounding loop

  the magnet 72 The loop is formed by a conductive carcass

  trice ring, of identical structure to that associated with the magnet 22 of Fig 1, and comprising a washer 36a, an outer ring 34a, a ring 38a The latter is

  connected to a conductive tube 80 fixed in electrical connection

  with the bottom 66, and passing through the lower partition 60

  in a direction axial to coaxially surround the sleeve 78 and the sleeve 63. The operation of the switch 10 according to Fig 3 is as follows: In the closed position shown on the left halfway, the current path in the circuit supply 26 to the fixed contact 18 corresponds to that of the switch of

  FIG. 1 The current flows from the fixed contact 18 towards the con-

  20 and the sleeve 63, then its direction reverses in the sleeve 78 after passing through the sliding contact 76- The current then flows in the washer 36a, the outer ring 34a, the ring 38a, the tube 80 , the bottom 66 and arrives at the connection pad 68 It is noted that the reverse circulation of the current in the movable contact 20 and the socket 78 inside the annular magnet 72 does not generate any degaussing field that could affect the magnetization of the second magnet 72, during the separation of the contacts 18, 20, the extinction of

  the arc is facilitated by the strengthening of the magnetic field

  in the breaking zone, resulting from the sum of the elementary radial fields of the two magnets 22, 72 The magnetic blow is combined with a pneumatic blow by expansion of the SF 6 gas through the tubular contacts

  18, 20 towards the envelope 12.

  According to a variant (not shown), the contact 18 instead of being fixed could be arranged semi-fixed thanks to the addition of an elastic means and a clamp or a sliding contact between the inner ferrule 32 and the contact 18. In the devices of Figures 1 to 3, the magnetization of the annular permanent magnet (s) 22, 72 is axial, but it is clear that the structure and magnetization of the magnet

  can be arbitrary, especially a heteropower magnetization

leire or radial.

  The invention is of course in no way limited to the modes of implementation more particularly described, but it extends to any other variant remaining within the scope of the

electrotechnical equivalents.

Claims (10)

  1 Switch (10) or rotating arc circuit breaker includes   nant: a sealed casing (12) filled with insulating gas of high dielectric rigidity, a pair of separable contacts (18, 20),   a permanent magnet (22, 72) generating a magnetic field   in the contact separation zone for imposing a rotation of the arc, a pair of connection pads (16, 68) in electrical connection with said contacts, and a current supply circuit (26, 74) arranged between each range (16, 68) and the corresponding contact (18, 20), and comprisinga first current path outside the magnet,   characterized in that the permanent magnet (22, 721)   turn one of the contacts, and that the latter is connected   electrically to the first external path of the   born (26, 74) by a second internal path shaped such that the sum of the currents flowing through the magnet is zero to avoid any demagnetizing field within the hollow space of the magnet.   2 switch according to claim 1, characterized in that the second path of the current supply circuit (26, 74) comprises a U-shaped flange with a hairpin section extending along the inner face of the permanent magnet.   (22, 72, the flow of the current being effected in   pours into the branches substantially parallel to the pin.   3 switch according to claim 1 or 2, characterized in that the permanent magnet (22, 72) has an annular shape and the second current path is   formed by an inner ferrule (32, 78), one of which   is connected to the first external path and whose ex-   opposite end is connected to a tube (44) or sleeve (63) for supporting the contact (18, 20), the inner ferrule (32, 78) being arranged coaxially between the magnet (22, 72) and the tube (44) or sleeve (63>.   4 switch according to claim 2 or 3, characterized in that the U of the pin of the second path of the   current is directed to the cut-off zone, and that the   tacts (18, 20) aligned in the axial direction of the enve-   cylindrical loppe (12) each have a smaller diameter   to the corresponding inner ferrule (32, 78).   Switch according to Claim 2, 3 or 4, characterized   rised by the fact that one (18) of the contacts surrounded by   axially by a first permanent magnet (22) hollow is   fixed, and has an annular contact end   placed in the vicinity of the front face (24) of the magnet (22).   6 switch according to claim 3 or 4, characterized in that one (18) of the contacts coaxially surrounded by a first permanent magnet (22) hollow is semi-fixed, and that the support tube (44) associated with the contact is connected to the inner ferrule (32) via a contact sliding or contact pliers.   Switch according to any one of the claims   3 to 6, characterized by the fact that the other 20 contact   bile in translation traverses axially a second permanent magnet (72) and is electrically connected to the corresponding inner shell (75) of the circuit (74) by a contact   slider (76), the second magnet (72) being arranged   the first magnet (22) and separated from the latter by a predetermined axial interval.   Switch according to any one of the claims   1 to 7, characterized in that the first and second   current paths in the circuits (26, 74) are connected   in series to form a conductive carcass slotted with revolution around the longitudinal axis of the casing (12), said casing being provided with annular recess   housing the corresponding permanent magnet (22, 72).   9 Autoexpansion switch according to any one of   of the preceding claims, the envelope (12) being   subdivided into a break chamber and a room of ex-   pansion, characterized in that one or both contacts (18, 20) are hollow to allow escape   towards the expansion chamber by the action of the in the break chamber.   Switch according to one of the preceding claims   characterized in that the permanent magnet   (22, 72) associated with the corresponding contact (18, 20)   any form of homopolar magnetization   axial or axial, or a heteropolar magnetization,