EP0772214A2 - Electrical switchgear - Google Patents

Abstract

The device has at least two contact carriers (32,38) arranged spaced apart on an axis (3). The contact carriers have at least one contact (36) which is movable along the axis (3). When the device is in the switched on state, this contact conductively bridges the distance between the contact carriers. The device also has a drive (39) which acts on the movable contact. This is controlled by a system lead system arranged above. During at least one switching process, the movable contact (36) can move with at least two different speeds. At least one of these speeds is optimally adapted to the respective physical conditions for the switch process in question.

Description

TECHNICAL AREA

The invention is based on an electrical switching device according to the preamble of claim 1.

STATE OF THE ART

The invention relates to a state of the art, for example, from the published patent application DE-A1-42 10 545. In this publication, an angle isolator for a metal-encapsulated gas-insulated high-voltage switchgear assembly is described as an electrical switching device, with two switching elements arranged in the insulating gas-filled metal encapsulation and which can be contacted or separated along an axis, each with a pin-shaped, axially extending pre-ignition contact, which is designed as a follow-up contact in one of the two switching elements and with the pre-ignition contact of a fixed both Switch pieces coaxially surrounding fixed contact and a running contact provided on a movable of both switching pieces, which forms a continuous current path in the switch-on position with the fixed contact.

With this isolator, the movable contact moves at an almost constant speed after the acceleration phase, both in the switch-off direction and in the switch-on direction.

SUMMARY OF THE INVENTION

The invention, as defined in the independent patent claims, is based on the object of specifying an electrical switching device which is designed to be more user-friendly and which has an increased switching capacity, and a method for its operation is also specified.

It is particularly advantageous that the switching movements of the switching device can be adapted to the physical requirements of the respective switching process, so that its switching capacity is improved, or the influences on the network caused by the switching process are minimized.

The electrical switching device is provided with at least two contact carriers arranged spaced apart on an axis, with at least one contact which is designed as a switching pin and is movable along this axis and which electrically bridges the distance between the at least two contact carriers when the switching device is switched on the drive that acts on the moving contact and is controlled by a higher-level system control system. The at least one movable switching pin can be moved at least two different speeds during the at least one switching process, and at least one of the at least two speeds is optimally adapted to the respective physical conditions which are decisive for the switching process in question.

Further exemplary embodiments of the invention and the advantages which can be achieved thereby are explained in more detail below with reference to the drawing, which only represents one possible embodiment.

BRIEF DESCRIPTION OF THE DRAWING

• Fig.1 einen Schnitt durch ein Gehäuse eines erfindungsgemässen elektrischen Schaltgeräts,
• Fig.2 einen vereinfachten Schnitt durch eine Ausführungsform eines erfindungsgemässen elektrischen Schaltgeräts,
• Fig.3 eine schematische Darstellung eines Verlaufs einer Ausschaltbewegung eines Kontakts eines erfindungsgemässen elektrischen Schaltgeräts, und
• Fig.4 eine schematische Darstellung eines Verlaufs der Kontaktgeschwindigkeit beim Ausschalten eines Kontakts eines erfindungsgemässen elektrischen Schaltgeräts.

Show it:

• 1 shows a section through a housing of an electrical switching device according to the invention,
• 2 shows a simplified section through an embodiment of an electrical switching device according to the invention,
• 3 shows a schematic representation of a course of an opening movement of a contact of an electrical switching device according to the invention, and
• 4 shows a schematic representation of a profile of the contact speed when a contact of an electrical switching device according to the invention is switched off.

Elements with the same effect are provided with the same reference symbols in all the figures. All elements not necessary for the immediate understanding of the invention are not shown.

WAYS OF CARRYING OUT THE INVENTION

A disconnector is considered first as an electrical switching device. 1 shows a section through a schematically illustrated housing 1 of this separator. The housing 1 is usually filled with an insulating gas under pressure, sulfur hexafluoride (SF ₆ ) is particularly suitable for this. The visible edges of the housing 1 are only indicated for the sake of clarity. This housing 1 is usually connected to earth potential together with the other encapsulation parts of a metal-encapsulated gas-insulated switchgear. The housing 1 has two axes 2, 3 lying in one plane, which intersect at an angle α. The angle α is generally designed as a right angle, but angles that deviate from the right angle are also conceivable for special applications. As a rule, the housing 1 is cast pressure-tight from an aluminum alloy. The housing 1 has at least four circular openings 4, 5, 6 and 7, which are provided with flanges 8, 9, 10 and 11. The opening 4 of the flange 8, the opening 5 of the flange 9, the opening 6 of the flange 10 and the opening 7 of the flange 11 are assigned. The openings 4, 5, 6 and 7 are arranged such that they are penetrated in the center by the axes 2, 3, namely the axis 2 penetrates the openings 4 and 6 and the axis 3 the openings 5 and 7. The flanges 8 , 9, 10 and 11 have surfaces which are arranged perpendicular to the respective axes 2, 3.

The opening 4 is closed here by a disk-shaped insulator 12 which has an electrically conductive pouring fitting 13. The pouring fitting 13 is screwed to a conductor 14. The insulator 12 is held by means of an outer ring 15, in which grooves are made to accommodate sealing rings, not shown. The outer ring 15 is composed of two identically designed metallic, electrically conductive rings. The insulator 12 and the outer ring 15 are held in position by a connecting flange 16 of a neighboring housing 17 which is screwed to the flange 8. The opening 5 is closed here by a cover flange 18. Between the cover flange 18 and the flange 9, an outer ring 15 is mounted, which receives the necessary sealing rings, not shown. However, it is also possible to dispense with this outer ring 15 and instead to provide the support surface of the cover flange 18 or the support surface of the flange 9 with a groove for receiving a sealing ring. The cover flange 18 is provided with a socket 19 which is closed in a pressure-tight manner by means of a screwed cover 20. A rupture disk and connections for the gas supply to the housing 1 can optionally be installed in the cover flange 18 or in the cover 20.

The opening 6 is closed here by a disk-shaped insulator 12 which has an electrically conductive pouring fitting 13. The gate fitting 13 is screwed to a conductor 21. The insulator 12 is held on the outside by means of an outer ring 15, in which grooves are inserted for receiving sealing rings (not shown). The insulator 12 and the outer ring 15 are held in position by a flange 22 of a neighboring housing 23 screwed to the flange 10. The opening 7 is closed here by a cover flange 18. Between the cover flange 18 and the flange 11, an outer ring 15 is mounted, which receives the necessary sealing rings, not shown. However, it is also possible to dispense with this outer ring 15 and instead to provide the support surface of the cover flange 18 or the support surface of the flange 11 with a groove for receiving a sealing ring. The cover flange 18 is provided with a socket 19 which is closed in a pressure-tight manner by means of a screwed cover 20.

The housing 1 and the closure parts described above enclose an interior space 24, into which the active parts of electrical switching devices which are subjected to high voltage, here, as already mentioned, these are the active parts of a disconnector. The covers 20 can be used for the installation of a wide variety of additional devices used in metal-encapsulated gas-insulated switchgear. The housing 1 can also be provided with additional connections which can be used for the installation of sensors and viewing windows for the optical control of the disconnector position. In FIG. 1, a viewing window 25 is provided in the center of the housing 1, which is installed in a cylindrically shaped connecting piece, the central axis of which runs perpendicular to the plane in which the axes 2 and 3 lie, and which also lies exactly through the intersection of the Axes 2 and 3 go. A viewing window of the same design is provided in the opposite wall of the housing 1 at the exact same location. The separating point of all separator variants is arranged centrally in the housing 1 in such a way that the viewing window 25 described above is controllable.

2 shows a simplified section through a schematically illustrated first embodiment of an electrical switching device designed as a disconnector for metal-encapsulated gas-insulated high-voltage switchgear in the switched-off state. This isolator is designed as a longitudinal isolator, such as is provided in the course of metal-encapsulated gas-insulated busbars. The conductors 14 and 21 here represent the respective ends of the busbar sections which are at high voltage potential. The conductor 14 is screwed to the metallic cast-in fitting 13 of the left insulator 12. On the side of the cast-in fitting 13 facing away from the conductor 14, a dielectrically favorable, electrically conductive angle connector 26 is connected, which has a connection surface inclined by an angle β relative to the axis 2. The angle β has the value 30 ° here, however, other values of the angle β are also conceivable in accordance with the geometry of the housing 1; an angle range of 25 ° to 35 ° for this angle β can generally be sensibly implemented. The inclined connection surface is screwed to a cylindrical intermediate piece 27. The side of the intermediate piece 27 opposite the connecting surface is screwed to a contact carrier 28. The intermediate piece 27 extends along an axis 29 which lies in the same plane as the axes 2 and 3 and which is inclined by the angle β with respect to the axis 2. The contact carrier 28 is designed to be dielectrically favorable, it is made of metal. A cylindrical counter-contact 30 is inserted into the contact carrier 28 and serves as a fixed pre-ignition electrode of the isolator. In the Contact carriers 28 are also embedded in spiral contacts 31, which take over the current flow when the isolator is closed. The counter contact 30 extends in the direction of the axis 3, which also forms the central axis of the counter contact 30.

The conductor 21 is screwed to the metallic cast fitting 13 of the right insulator 12. On the side of the cast-in fitting 13 facing away from the conductor 21, a dielectrically favorable, electrically conductive angle connector 26 is connected, which has a connection surface inclined by an angle β relative to the axis 2. Care is taken that these two angles β always have the same value. Accordingly, this angle β also has the value 30 ° here. The inclined connection surface is screwed to a cylindrical intermediate piece 27. The side of the intermediate piece 27 opposite the connecting surface is screwed to a contact carrier 32. The intermediate piece 27 extends along an axis 33 which lies in the same plane as the axes 2 and 3 and which is inclined by the angle β with respect to the axis 2. The axis 33 runs parallel to the axis 29.

The contact carrier 32 is designed to be dielectrically favorable; it is made of metal. Spiral contacts 34 for current conduction are embedded in the contact carrier 32. The movable isolating contact 35 is arranged in the center of the contact carrier 32. The movable isolating contact 35 is cylindrical, its axis coincides with the axis 3. The movable isolating contact 35 has a switching pin 36 which is enclosed by a tubular contact tube 37. When turning on the Isolator makes the contact tube 37 after the switching pin 36 contact with the spiral contacts 31 of the contact carrier 28, when the isolator is switched off, the contact tube 37 first detaches from the spiral contacts 31 of the contact body 28, the switching pin 36 only then detaches from the mating contact 30. An insulating rod 38 , which is actuated by a drive 39, sets the movable isolating contact 35 in motion. The drive 39 is attached to the upper neck 19. The drive 39 has a speed-controlled DC motor, the rotor of which is equipped with permanent magnets. The control commands for the speed-controlled DC motor are generated by a higher-level system control system, not shown. The insulating rod 38 is led out of the housing 1 in a pressure-tight manner. The insulating rod 38 is moved by the speed-controlled direct current motor via a lever gear, and a rotary leadthrough is generally used as a pressure-tight leadthrough. The side of the movable isolating contact 35 facing the drive 39 is covered by an electrically conductive shield 40 made of an electrically conductive material. The movable isolating contact 35 extends along the axis 3, which also forms the central axis of this contact. The spiral contacts 34 enclose the contact tube 37 and connect it to the contact carrier 32 in an electrically conductive manner.

In the switched-on state of the disconnector, the current flows from the conductor 14 through the cast-in fitting 13, the angle connector 26, the intermediate piece 27, the contact carrier 28, the spiral contacts 31, the contact tube 37, the spiral contacts 34, the contact carrier 32, the intermediate piece 27, the angle connector 26 and the pouring fitting 13 in the conductor 21.

3 shows a schematic representation of the course of the switch-off movement s of the switching pin 36 as a function of the time t. The movement of the contact tube 37, which is provided for guiding the nominal current, is not considered further here. At the instant T ₀ , the closed disconnector receives a switch-off command. Shortly thereafter, at the instant T ₁ , the switch-off movement of the switching pin 36 begins. The drive 39 accelerates the switching pin 36 more and more until the contact is separated between the switching pin 36 and the counter-contact 30 at the instant T ₂ . The switching pin 36 is accelerated further until it reaches its maximum speed. This maximum speed for this isolator is, for example, in the range of around 300 mm / sec, but usually somewhat above 300 mm / sec, the speed of 330 mm / sec has proven particularly useful. Shortly after this maximum speed has been reached, the switching pin 36 is braked again, so that from the moment T _{3 it} moves further at a lower speed in the switch-off direction, this speed is in the range around 50 mm / sec. From the moment T ₄ , however, the switching pin 36 is accelerated again more strongly, to a speed of approximately 300 mm / sec. Shortly before reaching the switch-off position, the switching pin 36 is then braked again and then runs into the definitive switch-off position at the instant T ₅ .

4 shows a schematic illustration of the course of the speed v of the switching pin 36 as a function of the time t when the disconnector is switched off. This illustration also shows the three essential speed ranges A, B and C of the switching pin 36 described in connection with FIG. 3. Area A covers the time period between T ₂ and T ₃ area B comprises the time period between T ₃ and T ₄ and area C comprises the time period between T ₄ and T ₅ .

The comparatively high maximum speed in area A has the advantage that only a comparatively short period of time remains for the reignitions which may occur in this area A as a result of so-called "loop current circuits". As a result of this advantageous limitation of the possible number of re-ignitions and the associated reduction in the erosion, the service life of the switching pin 36 and the mating contact 30 is advantageously extended, which results in a significantly increased availability of the isolator. In the case of a switchgear assembly which is provided with a double or multiple busbar system, “loop current circuits” are understood to be the operational switchovers under load from one busbar system to another using the isolator.

The comparatively low speed in area B has the advantage that when capacitive currents are switched off after passing through area B, only a comparatively low "trapped charge" remains in the metal-encapsulated gas-insulated high-voltage system. Capacitive residual charges remaining on the active parts of the high-voltage system are referred to as "trapped charge". These residual charges are largely reduced by reignitions occurring in area B between the counter contact 30 and the switching pin 36. These residual charges also influence the size of the transient overvoltages, ie the smaller these residual charges are, the smaller the values of the too expected transient overvoltages. However, the speed of the switching pin 36 should again not be so slow in area B that the number of reignitions occurring in this area becomes too large, since each of these reignitions causes corresponding compensation processes and thus also undesirable steep voltage peaks (VFT, very fast transients).

In area C, the switching pin 36 is then accelerated again to a comparatively high speed in order to achieve that the position of the switching pin 36 which corresponds to the full separation distance is reached as quickly as possible, ie this distance between the switching pin 36 and the mating contact 30 withstands any voltage spike occurring in the metal-enclosed gas-insulated switchgear in question. At time T ₅ , the switching pin 36 has reached its definite switch-off position, and its entire switch-off stroke has been completed.

When the isolator is switched on, the isolating rod 38 actuated by the drive 39 moves the movable isolating contact 35 along the axis 3 towards the fixed counter contact 30. A pre-ignition between the switching pin 36 and the fixed counter contact 30, which may be caused by residual charges and / or by an operating frequency voltage present between the contact carrier 32 and the contact carrier 28, is perfectly controlled by the isolator. An expansion of the pre-ignition arc towards the wall of the housing 1 cannot occur due to the geometrical arrangement of the isolating active parts. The drive 39 of the isolator is designed such that it reliably moves the movable contact arrangement 35 into the intended position in every possible operating case Switched on position moves, so that a perfect power supply is always guaranteed via the contact tube 37 provided for this purpose and the spiral contacts 31 and 34. In the case of a disconnector, when switching on, the aim is generally to achieve the highest possible speed of the switching pin 36 during the entire switching-on process; the grading of the switching-on movement, which is also possible in itself, is not used in this electrical switching device, since it would not make physical sense.

This drive principle used here for a disconnector, which optimally adapts the movement of the switching pin 36 to the physical conditions to which disconnector switching processes are subject, can of course also be used, modified accordingly, for other switching devices and other switching processes. In particular, circuit breakers with non-uniform contact movements are conceivable, in particular it is also conceivable that different contact movements are provided depending on the switching action to be carried out. When small inductive currents are switched off, the switch-off movement could, for example, take place so slowly with a blow piston switch that the blowing of the arc takes place so gently that the arc is broken off before the zero crossing, so that no overvoltages caused by the breaking off can occur, protective measures against such Overvoltages would therefore not have to be provided, a substantial reduction in the cost of the switchgear in which this circuit breaker is used would be the advantageous consequence. In the case of a power cut-off, however, the same blow piston switch would work with a comparatively high contact speed in order to operate in one of the usual piston-cylinder arrangement in the shortest possible time to generate the blowing pressure required for blowing the arc.

Adapting the movement sequences of switching devices to the physical conditions of the corresponding switching operations is advantageous in all areas of electrical energy distribution, i.e. at all voltage levels, in open-air and encapsulated switchgear and also in direct and alternating current networks. When optimally adapting the contact movement, the influences of different insulating and / or extinguishing media, for example liquid or gaseous media, could also be taken into account very simply.

LIST OF DESIGNATIONS

1

casing

2.3

axes

4,5,6,7

openings

8,9,10,11

Flanges

12th

insulator

13

Sprue fitting

14

ladder

15

Outer ring

16

Connecting flange

17th

Neighboring housing

18th

Cover flange

19th

Support

20th

cover

21

ladder

22

Connecting flange

23

Neighboring housing

24th

inner space

25th

Viewing window

26

Elbow connector

27

Spacer

28

Contact carrier

29

axis

30th

Counter contact

31

Spiral contacts

32

Contact carrier

33

axis

34

Spiral contacts

35

movable isolating contact

36

Switching pin

37

Contact tube

38

Insulating rod

39

drive

40

shielding

α, β

angle

s

path

t

time

v

speed

ABC

Areas

Claims (9)

Electrical switching device with at least two contact carriers (32, 28) spaced apart on an axis (3), with at least one contact (switching pin 36) movable along this axis (3), which in the switched-on state of the switching device determines the distance between the at least two contact carriers ( 32, 28) bridged in an electrically conductive manner, with a drive (39) which acts on the movable contact and is designed to be controllable by a higher-level system control system, characterized in that - That the at least one movable contact (switching pin 36) is movable at least two different speeds during at least one switching operation, and - That at least one of the at least two speeds is optimally adapted to the respective physical conditions that are decisive for the switching operation in question. Electrical switching device according to claim 1, characterized in - That an electric motor is provided as the drive (39). Electrical switching device according to claim 2, characterized in - That a speed-controlled DC motor is provided as an electric motor. Electrical switching device according to one of claims 1 to 3, characterized in that - That as an electrical switching device, a disconnector with a movable contact, which is designed as a switching pin (36), is provided, the switching-off movement of the switching pin (36) in three areas (A, B, C) each having different speeds. Electrical switching device according to claim 4, characterized in that a maximum speed of over 300 mm / sec, but in particular 330 mm / sec, is provided in the first area (A), - A speed in the range of 50 mm / sec is provided in the second region (B) adjoining the first, and - That a speed in the range of around 300 mm / sec is provided in the third region (C) adjoining the second. Electrical switching device according to one of claims 1 to 3, characterized in that - That a circuit breaker is provided as an electrical switching device. Electrical switching device according to claim 6, characterized in - That the drive (39) is excited by the higher-level system control technology so that the at least one movable contact of the circuit breaker, depending on the upcoming switching case, with a correspondingly adjusted speed or with passes through at least two different speeds the stroke corresponding to this switching case. Electrical switching device according to one of claims 1 to 3, characterized in that - That an earthing switch, a fast earth electrode or a load switch is provided as the electrical switching device. Method for operating an electrical switching device, with at least two contact carriers (32, 28) spaced apart on an axis (3), with at least one contact (switching pin 36) which can move along this axis (3) and which, when the switching device is switched on, the distance between bridging the at least two contact carriers (32, 28) in an electrically conductive manner, with a drive (39) acting on the movable contact and being controlled by a higher-level system control system, - That the at least one movable contact (switching pin 36) moves at least two different speeds during at least one switching operation, and - That at least one of the at least two speeds is optimally adapted to the respective physical conditions that are decisive for the switching operation in question.

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