FR2611310A1 - SWITCH FOR HIGH CURRENT - Google Patents

Abstract

THIS SWITCH FOR HIGH CURRENT 1 INCLUDES A VACUUM CUT-OFF CHAMBER 6 AND A CURRENT PATH 2 PER PHASE SURROUNDED BY ANTI-MAGNETIC METAL SHIELD 16. VACUUM CUT-OFF CHAMBER 6 INCLUDES A CUT-OFF POINT SUBJECT TO AN AXIAL MAGNETIC FIELD. CURRENT PATH 2 IS SUBDIVIDED INTO A 4 POWER CURRENT PATH AND A PARALLEL 3 NOMINAL CURRENT PATH. VACUUM CUTTING CHAMBER 6 IS ARRANGED IN THE POWER CURRENT PATH.

Description

IITERRUPTEUR FOR COU-RANT FORT

  The invention starts from a high-current switch having at least one current path per phase having at least a first vacuum breaking chamber. It relates in particular to a switch for high current of which at least one current path is surrounded by an antimagnetic metal shielding, the vacuum breaking chamber having at least one cutoff point fed with an axial magnetic field. We know, according to the article "The new Generator Switch for 8000 A" of the Siemens company (order number E 139 / 2067-101), a switch for high current of the aforementioned type. In this switch, which is intended to be mounted in generator connections, three vacuum-break chambers per phase are connected in parallel, since only in this way is the relatively high nominal current of 8000

A can be driven permanently.

  The permissible rated current of the commercial vacuum interrupter chambers is limited, since it is only through the connecting pieces exiting the vacuum breaking chambers that the dissipated heat can be removed. An increase in the permissible rated current is only possible at the cost of a complication

  relatively large and unprofitable.

  The object of the invention is to improve this state of affairs. The invention solves the problem by providing a high-current switch with vacuum interrupter chambers in which the vacuum interrupters are not constantly supplied with power, but only briefly for periods of time.

  shutdown and switch-on operations.

  This object is achieved in that the current paths comprise at least a first power current path and at least one current path connected in parallel with the first power path, and in that when circuit, the cut-off point of the first vacuum cut-off chamber (s) located in the first power flow path (s) opens after switching current to interrupt on (s)

  first power line (s).

  The advantages obtained by virtue of the invention consist mainly in that, when switching off, the vacuum breaking chambers are uniformly charged and can thus be better used. When switching on also, the switching current is distributed uniformly over the vacuum interrupters after the pre-priming, so that overloading of the individual vacuum interrupters can also be excluded here. . Another considerable advantage is that vacuum interrupter chambers suitable for relatively low nominal currents can be used in high-current switches, so that this disadvantage can be neglected while the good ones can be fully utilized. switching properties. The invention, its developments and the advantages which can thus be obtained will be explained in more detail below with reference to the attached drawing, which simply represents a possible embodiment, drawing in which: FIG. 1 is a schematic drawing of FIG. of a switch for high current according to the invention, FIG. 2 shows a first embodiment of the high-current switch of the invention, FIG. 3 represents a second embodiment of the high-current switch of FIG. FIG. 4 shows a third embodiment of the high current switch of the invention, and FIG. 5 shows a fourth embodiment of the high current switch of the invention. In all figures the elements having the

  same action have the same reference numbers.

  FIG. 1 represents a block diagram of a switch for a strong current 1 according to the invention. This switch 1 can be made for one or more phases. A current path 2 enters the switch 1 and divides into a nominal current path 3 and a power current path 4 parallel to the previous one. The nominal current path 3 has an auxiliary cut-off point 5 which is shunted by the power flow path 4 in which a vacuum breaking chamber 6 is provided with a cut-off point 7. The vacuum breaking chamber is preceded by and followed by coils 8, 9 which feed the breaking point 7 with an axial magnetic field. The coils 8, 9 are not spatially located next to the vacuum breaking chamber 6, as shown in the drawing, but they concentrically surround the vacuum breaking chamber 6 in the region of the cutoff point 7 and are connected to each other. to it mechanically through insulating supports. The coils 8, 9 are arranged at an equal distance from the open cut-off point 7 and their longitudinal axis coincides with the longitudinal axis of the vacuum breaking chamber 6. In addition, the distance between the two coils 8, 9 is in no case greater than the inside diameter of the coils. Each coil 8, 9 has the same number of turns, namely at least one turn and at most five, however, preferably two. The coils 8, 9 may be wound in one or more layers; the number of turns does not have to be an integer. An input terminal 10 is electrically connected to one end of the coil 8, the other end of which is electrically connected to the vacuum breaking chamber 6 via an electrically conductive connecting piece. The vacuum interrupter chamber 6 is connected, via another connecting piece & one end of the coil 9 of which

  the other end is connected to an output terminal 11.

  When switched off, the auxiliary cut-off point 5 is opened first and the current to be switched off is switched on the power flow path 4. Then, only, the vacuum interrupter chamber 6 is open and an electric arc bursts at the cutoff point 7. The two coils 8, 9, of the same dimensions and identical structure, are traversed in the same direction by the current to be switched off and together they cause an axial magnetic field acting on the point 7 and on the arc formed at this point during the switching off operation. In the region of the cut-off point 7, this magnetic field is practically homogeneous thanks to the geometrical arrangement of the coils 8, 9; moreover, it is proprotional to the current and has the effect that the arc burns diffusely, even with current values in the range of 50 kA and far beyond, so that contact wear at the cutoff 7 remains within controllable limits. Such current values can be controlled and switched off only thanks to the strong axial magnetic field due to the relatively

high windings of the coils 8, 9.

  In FIG. 1, as in the following FIGS. 2 to 5, all the mechanical drive elements actuating the auxiliary cut-off point 5 and the corresponding vacuum breaking chambers are not indicated. Furthermore, in FIG. 1, no antimagnetic shielding is shown around

  each phase of the switch for high current 1.

  Figure 2 shows another switch for high current 1, namely in the upper half of the figure in the circuit state, and in the lower half, in the off state. The current path 2 is tubular in shape and is supported by insulators 15 against a metal shield 16 disposed coaxially. This metal shield 16 is also tubular and consists of an antimagnetic metal. Feet 17 fixed on the metal shield 16 make it possible to fix the switch for high current 1 on foundations. The front ends of the metal shield 16 and the current path 2 include connection possibilities for the electrical connection with known single phase metal shielded generator connections. Provided in the metal shield 16 are mounting and inspection apertures, as well as perforations for the mechanical drive members. These openings and these perforations are generally hermetically sealed in the high-power high-power switches 1, since all the generator connections are subjected to a slight overpressure to reduce the risk of clogging of the insulators 15. such generator connections also have forced ventilation to ensure proper evacuation of

the heat dissipated.

  The nominal current path S comprises a continuity solution which is shunted by the auxiliary cut-off point 5 when the high-current switch 1 is in circuit. The auxiliary cut-off point 5 is indicated here by contact fingers, the number of which can be chosen according to the value of the nominal current. Some of these contact fingers may lag behind others when switching off, so that switching arcs can only be formed on these late contact pins. The other contact fingers are thus spared and always ensure perfect guiding of the nominal current. When switched on, these contact fingers, which then close first, also collect the switching loads. The contact fingers are mounted in a not shown support, which is moved by a drive device. There are shown here simply two power current paths 4 parallel to the nominal current path. Each of these power current paths 4 corresponds to the power current path 4 described in FIG. 1. The power current paths 4 are here arranged inside the current nominal current path 10 and are symmetrical with respect to each other. to the axis of the path 3. The power current paths 4 each have the same impedance value with a mainly inductive percentage. As a result, when the power current paths 4 are supplied with current, a distribution is obtained. uniformity of the current on all power current paths 4, which results that none of the vacuum interrupter chambers 6 is overloaded. The power switching capacity of each vacuum interrupter chamber can thus be fully used and without safety margin. The operating mode of this switch

  for high current 1 will be briefly explained.

  When the high-current switch 1 guides the nominal current, the auxiliary cut-off point 5 is closed and all of the nominal current flows from the

  current flow 2 by the nominal current path 3.

  The power current paths 4 are in the space without a field & within the path of

  rated current 3 and therefore do not guide current.

  After a cut-off order for a switching operation, or for a short-circuit cut, the auxiliary cut-off point 5 opens and the entire current is switched uniformly distributed over the power current paths 4. Next only the vacuum cut-off chambers 6 are open and generally cut off the current at the next passage of the current at zero, at the off state, the auxiliary cut-off point 5 and the chambers of

2 6 1 1 3 1 0

  vacuum cut 6 remain open, and the existing current during the cutoff flows, uniformly

  distributed in the power current paths 4.

  Immediately thereafter, the auxiliary cut-off point 5 also closes and the current is switched from the power current paths 4 to the nominal current path 3. During both switching operations, the vacuum breaking chambers 6 are only very briefly loaded. by the current so that it does not

  does not result in significant thermal load of these.

  For this reason, the vacuum interrupter chambers 6 can withstand without difficulty cycles of

  switching succeeding briefly.

  For most areas of use, a vacuum flow chamber 4 per power flow path 4 should provide sufficient dielectric strength. However, it is possible without problem to mount in series two vacuum interrupter chambers 6, or more, per power current path to thereby achieve a higher dielectric strength. As shown in FIG. 3, it is also possible to arrange the power current paths 4 outside around the nominal current path 3. This arrangement, also symmetrical with respect to the center, has the advantage that it is possible to place a greater number of power current paths 4, uniformly distributed on the periphery. This high current switch is suitable for

  nominal currents higher than that of Figure 2.

  With this switch for high current 1, it constantly passes, in the circuit state, negligible small currents in the power current paths 4, because of the film effect. However, because of the impedance of the various power current paths 4, these small currents are limited to negligible values, so that the pre-heat load of the various chambers can be neglected.

vacuum cut 6.

  Figure 4 shows a combination of the arrangements of Figures 2 and 3 suitable for particularly strong currents. With this switch for high current 1, it must be ensured that the impedances of the power current paths 4 situated inside the nominal current path 3 and those of the power current paths 4 situated at

outside are equal.

  When there is very little room for the installation of the high-current switch 1, it is also possible to make the insulators 15 in the form of pressure-proof disc insulators and to hermetically close off the pressure. current path 2 inside on both sides of the high-current switch 1. The volume thus procured can be filled with an insulating medium, for example compressed air or SF6 gas. It is thus possible to reduce the insulation distance, and thus the dimensions of the switch; in addition, the power flow paths 4 and the vacuum breaking chambers can be placed closer to one another.

associated 6.

  FIG. 5 represents another variant of a switch for high current 1, similar to the embodiment of FIG. 3, and which can also be

  use in all other embodiments.

  In each of the power current paths 4 are additionally mounted an Is limiter (target current) and, in parallel with it, a detector 21. The signals received by the detectors 21 are controlled and processed in a control unit. 22. As indicated by the dashed lines of action 23, the evaluation unit 22 can act simultaneously on all the limiters of IE 20 and trigger them simultaneously; however, it may be designed so that it simply triggers certain determined Is limiters. The power current paths 4 are then interrupted. Such a redundant mounting possibility increases the safety when switching off the high-current switch l. If, for example, a vacuum interrupter chamber 6 is not to be shut down, the detector 21 of the defective power-current path 4 would indicate it. In the evaluation unit 22, it would be found, for example, that it still passes current in one of the power current paths 4 of the phase fading first, namely the entire current to be interrupted; for this reason, the evaluation unit 22 would instantly trigger all limiters Is 20. In a three-phase group of switches for high current 1, all Is limiters. 20 would be triggered in all three phases. In order not to have to search in all the power current paths 4 for the causes of triggering of the Is limiters 20, provision is made in the evaluation unit 22 for a device which makes it possible to identify the detector 21 which has This triggers the trip, and thus also the defective power current path 4. After a trip, Is limiters 20 must be manually reset and reset. However, this complication is perfectly Justified if one thinks of the damage which, because of this, can be

  avoided to the generator and other contact parts.

  In the case of the defect mentioned, it is also conceivable to trigger only Is 20 limiters of the first off phase, or to trigger only the I limiter. 20 of the defective power current path 4 and let the other two phases of the three-phase group normally stop. For this assembly, however, there is a need for an electronic evaluation unit 22 working very quickly. It is also wise, when a fault appears only in one of the phases going out second, to trigger only Is limiters. 20 of this defective phase, or to trigger only the limiter Is 20 of the power path 4 defective power, because we can reduce the time spent and

  the work for the revision of Is Limiters, 20.

  After triggering an I limiter. 20, the evaluation unit 22 must block each switch-on of the high-current switch 1 until it is revised, and again fully ready for operation. The evaluation unit 22 must always be calculated so as to ensure optimal use of the In limiters. 20. In addition, he must assert that, when put in circuit, it can not occur

  inadvertent tripping of IS limiters 20.

  Such strong-current switches 1 equipped with vacuum-breaking chambers 6 are particularly suitable, because of the extremely low tendency to overhaul the vacuum interrupter chambers 6, for pumped storage power plants whose generator switches must be calculated for extremely large numbers of operations. For switches for high current 1 which are required to have a lower breaking power, as might be the case, for example, for high current load break switches, it would suffice to provide only a power current path 4 with at least one vacuum breaking chamber 6 without the coils 8 and 9. To cut charging currents, the breaking capacity of this vacuum breaking chamber 6, whose contacts are mounted so that a field occurs. magnetic

axial weak, would suffice.

he

Claims (10)

  1. - switch for high current (1) comprising at least one current path (2) per phase comprising at least a first vacuum breaking chamber (6) and surrounded by an antimagnetic shield (16), the breaking chamber under vacuum (6) having at least one cut-off point (7) subjected to an axial magnetic field, characterized in that: - the current path (s) (2) comprise at least one first current path of power (4) and at least one nominal current path (3) connected in parallel with this first power path (s) C4); and in that - when switching off, the cutoff point (7) of the first (s) vacuum chamber (s) (6) located in the first path (s) ( s) of power current (4) opens (s) after the switching of the current to be interrupted on this (s) first (s) current path (s) power (4).   2. - switch for high current according to claim 1, characterized in that: - the (s) pathCs) rated current (3) is (are) hollow, and that - the (the) first (s) roomCs) the vacuum interrupter (6) is (are) disposed within the   (a) path (s) of rated current (3).   3. - switch for high current according to claim 1, characterized in that - the (s) path (s) rated current (3) is Csont) hollow, and - (Cles) chamberCs) vacuum cut (6) ) is (are) arranged outside the path (s) rated current (3).   4. - Power switch according to one   any of claims 1 to 3, characterized in that   that - at least one second vacuum interrupter chamber (6) is provided in the second power flow circuit (s) (4) mounted in parallel with the first (s) ) power path (s) (4), and - each of the power current paths (4) has the same impedance value with a percentage mainly inductive.   5. - switch for high current according to claim 4, characterized in that - the (the) first chamber (s) of vacuum cutoff (6) is (are) arranged (s) outside the   (of) current current (3).   6. - switch for high current according to claim 5, characterized in that - each vacuum-breaking chamber (6) is associated with at least two coils (8, 9) of the same dimensions and traversed by the current in the same direction, one of which is electrically mounted before the corresponding vacuum interrupter chamber (6) and the other after this room.   7. - switch for high current according to claim 6, characterized in that - the coils (8, 9) concentrically surround the vacuum interrupter chamber (6) concerned in the region of its cutoff point, each of the coils (8 , 9) comprises at least one and at most five, preferably two, turns, and - these coils (8, 9) are in no case further from each other than from the length of the inner diameter of the coils.   8. - Power switch according to one   any of claims 1 to 3, characterized in that   in the first power path (s) (4) there is provided an I. limiter (20) and a detector (21), and the detector (21) is connected to an evaluation unit (22) which can act on the I limiter. <20). 9. - Power switch according to one   any of claims 4 to 7, characterized in that   in each of the paths (at least two) of power current (4), an IE limiter (20) and a detector (21) are provided each time and all the detectors (21) are connected to one evaluation unit (22), which can act either simultaneously on all the Is limiters (20), or selectively on Ir. limiters determined <20). 10. Power switch according to claim 9, characterized in that - in the evaluation unit (22> a device is provided for identifying the detector (s) <21). emitting signals.