EP2056321B1 - High-voltage power switch with a rotating light arc - Google Patents

Abstract

The high-voltage power switch has a housing (1) filled with insulating gas, and a heating volume (14) for accepting compressed quenching gas. A coil segment (51) is provided, which has a winding (53) of a coil (50). Arc race (15) is also provided, which is disposed at a gap (D) from each other in the axial direction. An axially oriented segment of a ferromagnetic core (40) is formed as a hollow cylinder (41), and is extended into the gap.

Description

TECHNICAL AREA

The present invention relates to a high-voltage circuit breaker according to the preamble of claim 1. Such a switch is generally used to interrupt high-power alternating currents in power grids with nominal voltages between 1 and several 100 kV, in which these alternating currents are generated, transmitted or distributed.

In a switch of the aforementioned type, the energy of a switching arc formed when interrupting a short-circuit current in an arc zone is utilized in order to provide an extinguishing gas which blows over a zero crossing of the current beyond the switching arc. Here, the current to be interrupted is passed through a coil. The magnetic field of the coil causes a rotation of the switching arc about the coil axis. Resulting hot and pressurized arc gas is passed through a heating channel in a heating volume of the switch and stored there as quenching gas. The pressure of the arc gas grows disproportionately with the size of the stream and may possibly reach undesirably high values.

STATE OF THE ART

A switch of the type mentioned is described in EP 75 341 , This switch has a power current path arranged in an insulating gas-filled housing with two contact pieces which can be displaced relative to one another along an axis, one of which has an arc contact, an arc runner, a cylindrical coil surrounding the arc contact and a ferromagnetic coil core in a coaxial arrangement. When this power is turned off, a current that is to be interrupted flows through this coil. The magnetic field of the current acts on a switching arc which opens on the arc running ring when the power current path is opened. Under the influence Electromagnetic forces now rotates the held on the race switching arc around the axis and heats the insulating gas. In this case, formed arc gas is passed from a arc receiving arc of the arc into a heating volume and stored as quenching gas. When approaching the current to be disconnected to a zero crossing, the quenching gas then flows from the heating volume into the arc zone and in this case bleeds the switching arc until the current is interrupted.

For a successful blowing of the switching arc and thus for a successful interruption of the current, it is necessary that the pressure of the extinguishing gas reaches a certain minimum value. Seen over the entire spectrum of currents to be interrupted, which extends over several orders of magnitude from small over medium to large currents, no much greater quenching gas pressure is required for the successful interruption of a large current than for a small or medium current. However, since the pressure of the arc gas and thus also of the extinguishing gas increases disproportionately with the current, the arc gas generated by the arc switching on interrupting large currents to a magnitude higher pressure than at low currents. In order to keep the volume of the heating volume small, and so as to enable a production of the switch in an economical manner, therefore, the pressure is limited.

Another switch with a coil for generating a rotating switching arc is in EP 0 731 482 A2 described. In this switch, the coil is at least partially short-circuited. When large currents are switched, the size of the magnetic field is then reduced by partial or complete short-circuiting of the coil, so that the formation of arc gas is possibly drastically reduced. The volume of the heating volume can be kept so low. Further, the document discloses EP 0 932176 A1 a switch according to the preamble of claim 1.

PRESENTATION OF THE INVENTION

The invention, as indicated in the claims, has for its object to provide a switch of the type mentioned, in which the pressure of the heating gas provided in the quenching gas when switching off large currents is limited by simple means.

In the switch according to the invention, a first coil section containing the windings of the coil and the arc runner ring are arranged in the axial direction at a distance from each other and projecting an axially aligned and formed as a hollow cylinder portion of the ferromagnetic core in this distance.

The ferromagnetic core is now designed and arranged so that it is not already saturated when interrupting small currents, while already being saturated when large currents are interrupted. When interrupting small and possibly even medium currents, the core now acts as a kind of good magnetic conductor, which brings the magnetic flux of the coil largely unattenuated to the arc running ring. At the arc runner then acts a magnetic flux density, which is proportional to the magnetic flux density, which acts near the separated by the axial distance from the arc run of the coil windings. When interrupting large and possibly also medium currents, the core, on the other hand, acts as a kind of bad magnetic conductor, which no longer concentrates the magnetic flux of the coil and specifically guides it to the arc running ring. At the arc runner then acts a magnetic flux density, which is no longer proportional to the flux density, which acts on the separated by the axial distance windings of the coil. The pressure build-up of the quenching gas therefore increases with increasing strength of the current to be interrupted much lower than in a comparably designed switch, but in which no distance in the axial direction is provided between the turns of the coil and the arc running ring. Accordingly, the volume of the heating volume can be sized small or otherwise necessary means for limiting the pressure build-up can be omitted.

These advantageous effects are certainly achieved when the distance is at least 0.25 times the outer radius of the coil. To the Limit the extent of the switch in the axial direction, the distance should be at most twice the radius. A limitation of the extinguishing gas pressure in the heating volume sufficient even when switching very large short-circuit currents of several hundred kA is achieved if the distance is 0.5 to 1.5 times the radius.

Since there is sufficient space between the arcing contact and the coil, the hollow cylinder can also have a considerable wall thickness and thus a large amount of ferromagnetic material can be accommodated in this space. The magnetic flux density acting upon the interruption of a current is then not only evenly distributed over the arc runner, but at the same time it is also predominantly axially aligned. Since the current to be interrupted in the held on the arc runner base of the switching arc is guided predominantly radially, so acts a large and largely constant electromagnetic force on this base point. For small and possibly medium currents as a good heating power of the switching arc and thus an extinguishing gas is generated with sufficiently high pressure.

It is advantageous if the wall thickness of the hollow cylinder is at least 0.2 times its outer radius. On the one hand, it is thus avoided that the core is prematurely saturated even with comparatively small currents. On the other hand, however, a substantially constant magnetic flux density in the region of the arc running ring and thus also in the section of the switching arc which is located on the arc running ring is achieved.

So that the largest possible magnetic flux density acts at the location of the arc runner, the ferromagnetic hollow cylinder should bridge this distance. By bridging the distance is to be understood here that the hollow cylinder is brought directly to the arc running ring, but at least up to a comparison with the thickness of the arc running ring (expansion in the axial direction) small distance of typically a few millimeters.

The magnetically bridged by the ferromagnetic hollow cylinder of the core distance between the arc running ring and the turns of the coil contains a largely arbitrarily formed electrically conductive connection, which is suitable is to guide the current to be interrupted from the arc runner to the coil. A mechanically particularly stable embodiment of this connection and thus also of the switch according to the invention is achieved if a coil section formed as a second coil section adjoins the first coil section containing the turns, which is electrically conductively connected to the arc runner and comprises the hollow cylinder coaxially. Additional stability of the switch is achieved when the coil is made of a formed in the manner of a cup conductor. The wall of the cup is then generally formed by the first and second coil portion and the cup bottom can then serve as a power connection of the arc runner and have a central opening for performing the arc contact.

In order to largely suppress the formation of eddy currents, predominantly axially and radially aligned slots are formed in the second coil section designed as a conductor tube and / or in the ferromagnetic core.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig.1

eine Aufsicht auf einen längs einer Achse A geführten Schnitt durch eine als Generatorschalter ausgeführte Ausführungsform des Hochspannungsleistungsschalter nach der Erfindung, bei der der Schalter links der Achse im Einschaltzustand und rechts der Achse beim Ausschalten nach Bildung eines Schaltlichtbogens dargestellt ist, und

Fig.2

ein Diagramm, in dem die beim Ausschalten des Schalters nach Fig.1 sowie eines Schalters nach dem Stand der Technik jeweils in einer Spule des Schalters erzeugte axiale Komponente der magnetischen Flussdichte B [in arbiträren Einheiten] am Ort eines Lichtbogenlaufrings in Funktion der Stärke des abzuschaltenden Strom I [ kA] dargestellt ist.

With reference to drawings, an embodiment of the invention will be explained in more detail below. Hereby shows:

Fig.1

a plan view of a guided along an axis A section through an executed as a generator switch embodiment of the high-voltage circuit breaker according to the invention, in which the switch is shown left of the axis in the on state and right of the axis when switching off after the formation of a switching arc, and

Fig.2

a diagram in which the after switching off the switch after Fig.1 As well as a switch according to the prior art in each case in a coil of the switch generated axial component of the magnetic flux density B [in arbitrary units] at the location of an arc run as a function of the strength of the current to be disconnected I [kA] is shown.

WAYS FOR CARRYING OUT THE INVENTION

In all figures, like reference numerals refer to like-acting parts.
The in Fig.1 shown generator switch can turn off at high voltages up to 100 kV currents up to a still permissible maximum short-circuit breaking current of typically 250 kA. It contains a housing 1 filled with a compressed insulating gas, for example based on sulfur hexafluoride, nitrogen or carbon dioxide or a gas mixture based on one or more of these gases, and a contact arrangement received by the housing 1 and largely axially symmetrical with two along an axis A relative When switched on, the two contact pieces 2 and 3 are not shown with rated current contacts in a schematically indicated low-resistance Nennstrompfad N and with an arcing contact 21 and an arc contact 31, a ferromagnetic core 40 and a coil 50 in one dashed lines shown power current path L, which is guided parallel to the nominal current path N.

The apparent tubular, but optionally also massively configured, arc contact 21 is guided by an insulating tube 11 acting as an auxiliary nozzle and contacted in the on state of the switch (left half of Fig.1 The insulating tube 11 and a held on the contact piece 3 insulating 12 limit an annular heating channel 13, which when turned off (right half of Fig.1 ) connects an arc zone, which receives a switching arc S, with a heating volume 14.

The switching piece 3 is fixedly held in the housing 1 and formed largely in the manner of a hollow cylinder. The switching piece 3 contains in a coaxial arrangement from the inside to the outside the tubular, designed in the manner of a tulip arcing contact 31, the ferromagnetic core 40 and the coil 50. At its the contact piece 2 facing end face, the contact piece 3 an arc runner 15 made of a erosion-resistant material , in particular graphite, a retaining ring 16 made of metal or possibly of insulating material for fixing the arc running ring 15 on an end face of the coil 50 and the insulating washer 12 which is seated on the retaining ring 16 and the arc runner 15 is limited radially outwards.

The coil 50 is made of a trained in the manner of a cup conductor of aluminum or copper resp. made of an aluminum or copper alloy. The wall of the cup is formed by two coil sections 51 and 52, of which the first section 51 contains all, for example four turns 53, of the coil 50. The coil section 51 has a distance D to the arc runner 15 in the axial direction. The subsequent to the section 51 second coil section 52 is formed as a conductor tube. An attached to the portion 52 cup bottom serves as a power connection 54 and is electrically connected to the arc runner 15. In the cup bottom, a central opening 55 is formed through which the arcing contact 31 is guided. At the side facing away from the cup bottom cup edge a radially outwardly extending annular power connector 56 is attached. In the designed as a conductor tube second coil section 52 a plurality of axially and radially aligned and circumferentially uniformly distributed slots 57 are formed in the conductor tube, of which only one Fig.1 can be seen.

The ferromagnetic core 40 has a longitudinal axis A aligned and protruding in the distance D first portion 41, which is designed as a thick-walled, the arc contact 31 radially comprehensive hollow cylinder. The hollow cylinder 41 is supported with its upper end face on the power connector 54 of the coil and thus bridges the distance D magnetic. The distance of typically several millimeters between the upper face of the hollow cylinder 41 and the arc runner 15 formed by the power connector 54 reduces the magnetic flux at the location of the arc runner 15 (expansion of the ring 15 in the axial direction) only insignificantly since it is considerably smaller than the thickness of the arc runner is dimensioned. To the hollow cylinder 41 is followed by a likewise designed as a thick-walled hollow cylinder second portion 42 of the ferromagnetic core 40, which is radially enclosed by the coils 53 containing the turns 53 coil. In the inner wall of the hollow cylinder 41, an annular groove is formed, in which a mounted on the contact carrier of the arcing contact 31 outer flange 32 is rigidly held. As in the section 52 of the coil 50 are also in the ferromagnetic core 40 axially and radially extending, but now marked with the reference numeral 43, slots formed. These slots and the slots 57 serve to suppress eddy currents.

The individual parts of the contactor 30 are generally connected by screwing together, but may also be interconnected by other means, such as the arc runner 15 and the coil 50 by a clamping connection, in which the clamping force by the bolted to the coil 50 retaining ring 16 is applied, or the ferromagnetic core 40 and the tulip-shaped arcing contact 31 by press fit. Between the individual parts provided cavities are filled with insulating material. This material is in Fig.1 not shown. Such cavities are about the slots 43, 57 or the insulating distances between the individual windings 53 and the power terminals 54, 56 or between the ferromagnetic core 40 and the windings 53, respectively. the arcing contact 31.

In the on state (left half of Fig.1 ), the nominal current path N and the power current path L are closed and the switch carries current, which flows predominantly in the rated current path and only with a share of about 1% in the power current path. To turn off the switching piece 20 is guided by a drive, not shown upwards. The nominal current path N opens first. The current to be switched off commutes completely into the current in the left half of Fig.1 dashed lines shown power current path L and flows from the arcing contact 21 via the arcing contact 31, the hollow cylinder 41 to the coil terminal 54 and from there through the coil 50 to the coil terminal 56th

In the course of the switching off the guided with friction in the arcing contact 31 arc contact 21 is out of engagement with the fixed contact piece 30 and then forms between the arcing contact 21 and contact fingers of the arcing contact 31 of the switching arc S, which commutes to the arc running ring 15 (right half of Fig.1 ). The commutation takes place rapidly, since the hollow cylinder 41 and the arcing contact 31 are taken from the power current path L and the current to be disconnected now from the arcing contact 21 via the Switching arc S, the arc runner 15 and the coil 50 to the power supply 56 flows.

In the vicinity of the arc runner 15, the current I to be disconnected flows in the arc S substantially in the radial direction. The current-carrying coil 50 and the ferromagnetic core 40 act in the region of the arc runner 15 with a predominantly axially aligned magnetic flux density B. Therefore, acting on the arc running ring 15 switching arc S acts a circumferentially directed electromagnetic force, which is a rotation of the arc S about the axis A causes. Resulting centrifugal forces produce a radially outwardly directed through the heating channel 13 into the heating volume 14 flow of arc gas. The arc gas is stored in the heating volume as a compressed quenching gas and then inflated when approaching the disconnected current I to a zero crossing the switching arc S until the power is interrupted.

When switching off small or medium currents (up to about 10% or between about 10 and about 30% of the maximum permissible short-circuit turn-off current), the magnetic field of the coil 50 is insufficient to achieve the saturation magnetization of the ferromagnetic core 40. Therefore, at the location of the arc runner 15, the magnetic field of the coil 50 is increased by the magnetization of the still-unsaturated ferromagnetic core 40. As long as the core is unsaturated, it is a much better magnetic conductor than the surrounding material, in particular insulating gas, aluminum or copper Coil 50 or graphite of the arc runner 15. The core 40 then carries the majority of the magnetic flux of the coil 50 and thus increases the magnetic flux density in the near the upper end face of the hollow cylinder 41 mounted arc runner 15th

When switching off large currents (about 30 to 100% of the maximum permissible short-circuit cut-off current), the saturation magnetization of the ferromagnetic core 40 is reached. In the magnetically saturated state, the core 40 is a similarly good resp. bad magnetic conductor like the surrounding material. With a saturated core, therefore, the magnetic flux of the coil 50 at a distance D is largely uniformly distributed to all material, such as the insulating gas and the aluminum or the copper of the coil 50, but also on the Ferromagnetikum of the core 40, so in particular also on the ferromagnetic hollow cylinder 41. Therefore, only a small part of the magnetic flux at the arc run 15, so that the magnetic flux density B at the site of the arc run 15 only slowly grows.

For small and low-sized average currents, therefore, the magnetic flux density at the arc runner 15 is practically the same as at the location of the coil section 51, whereas at large currents at the location of the arc runner 15, the magnetic flux density increases much slower with increasing current than at the location of the coil section 51.

This fact is from the in Fig.2 shown diagram. It can be seen from this diagram that in the embodiment of the switch according to the invention according to FIG Fig.1 with a still permissible maximum short-circuit breaking current of 250 kA, above about 40 kA, ie at high-sized medium and large currents, the magnetic flux density B at the location of the arc runner 15 and thus the pressure build-up by the switching arc S with increasing current strength of the current to be disconnected I substantially less than the magnetic flux density of an identically designed switch, but in which the ferromagnetic core 40 has no protruding from the turns 53 of the coil 50 in the distance D hollow cylinder 41. Accordingly, the volume of the heating volume 14 can be made smaller or can be dispensed with means for limiting the pressure build-up. Since it can be seen that the pressure build-up by the switching arc is higher at small and low rated average currents because of the magnetically not yet saturated ferromagnetic core 40 than in the switch of the prior art, blowing aids for the production of extinguishing gas can be made small.

LIST OF REFERENCE NUMBERS

1

casing

2, 3

contact members

11

insulating

12

insulating

13

heating duct

14

heating volume

15

Arcing ring

16

retaining ring

21, 31

Arcing contacts

40

ferromagnetic core

41, 42

hollow cylinder

43

slots

50

Kitchen sink

51, 52

coil sections

53

turns

54, 56

power connectors

55

opening

57

slots

A

axis

B

magnetic flux density

D

distance

I

electricity

L

Power current path

N

Current Path

S

Switching arc

Claims (11)

1. High-voltage circuit breaker having a housing (1) which is filled with insulating gas, having a heating volume (14) for holding compressed quenching gas, which is compressed by a rotating switching arc (S), which is subject to a current-dependent magnetic flux density (B), when a current (I) is interrupted, and having two switching pieces (2, 3), which can be moved relative to one another along an axis (A) and are arranged in the housing (1), one (3) of which has, arranged coaxially, an arc contact (31), an arc race (15) and a coil (50) which is provided with a ferromagnetic core (40) and with two electrical connections (54, 56), and which coil (50) surrounds the arc contact (31), and the current (I) to be interrupted flows through all of the turns (53) of said coil (50) in the same sense, and which coil (50) is electrically conductively connected via the first electrical connection (54) to the arc race (15) and via the second electrical connection (56) directly to a low-impedance rated current path (N) of the switch, which contains rated current contacts, characterized in that a first coil section (51), which contains all the turns (53) of the coil (50), and the arc race (15) are arranged at a distance (D) from one another in the axial direction, and in that an axially aligned section, which is in the form of a hollow cylinder (41), of the ferromagnetic core (40) projects into the distance (D).
2. Switch according to Claim 1, characterized in that the distance (D) is at least 0.25 times the external radius of the coil (50).
3. Switch according to Claim 2, characterized in that the distance (D) is at most twice the radius.
4. Switch according to Claim 3, characterized in that the distance (D) is 0.5 to 1.5 times the radius.
5. Switch according to one of Claims 1 to 4,
   characterized in that the wall thickness of the hollow cylinder (41) is at least 0.2 times its external radius.
6. Switch according to one of Claims 1 to 5,
   characterized in that the hollow cylinder (41) bridges the distance (D).
7. Switch according to one of Claims 1 to 6,
   characterized in that at least one predominantly axially and radially aligned slot (43) is formed in the ferromagnetic core (40).
8. Switch according to one of Claims 1 to 7,
   characterized in that a second coil section (52) is adjacent to the first coil section (51), is in the form of a conductor tube, is electrically conductively connected to the arc race (15), and coaxially surrounds the hollow cylinder (41).
9. Switch according to Claim 8, characterized in that the coil (51) is produced from an electrical conductor which is formed like a cup.
10. Switch according to Claim 9, characterized in that the wall of the cup is formed by the first coil section (51) and the second coil section (52), and in that the cup base is used as an electrical connection (54) for the arc race (15), and has a central opening (55) for the arc contact (31) to pass through.
11. Switch according to one of Claims 8 to 10,
    characterized in that at least one predominantly axially and radially aligned slot (57) is formed in the second coil section (52), which is in the form of a conductor tube.

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