EP1180776B1 - Fast mechanical switch - Google Patents

Abstract

A switching station for a high/medium voltage switch has two fixed contact makers (1,2), a rotary electrically conductive bridging contact maker (3) and a driving mechanism for moving the bridging contact maker, which fits in between the fixed contact makers when the switching station is closed and short-circuits it. The driving mechanism is assembled from two coils (5,6) that encircle the bridging contact maker.

Description

TECHNICAL AREA

In the invention, it is assumed that a switching point of a high or medium voltage switch according to the preamble of claim 1. Such switches are used in the high or medium voltage level as a mechanical power switch or as a mechanical circuit breaker with a arc duration of at most a few 100 microseconds.

STATE OF THE ART

Such a switching point is described in the earlier European patent application number 99810596.9 (EP 1 067 569 A).

The switching point of a high or medium voltage switch contains two fixed contact pieces, which are cylindrical and coaxially into one another form an annular gap. A movable, formed in the form of a contact ring bridge switching piece is fitted in the closed state of the switching point in the annular gap. Coils of an electro-dynamic drive are arranged on both sides of the contact ring in order to move the contact ring in the axial direction.

To open the switch point, a current is fed into one of the two coils. In the contact ring eddy currents are induced, which are directed substantially opposite to the current in the coil. As a result, coil and contact ring repel each other, which leads to a translational acceleration of the contact ring and thus to the opening of the switching point.

To close the switching point of the current is fed into the other of the two coils, after which the contact ring moved back to the starting position and the switch is thus closed again.

A similar switch is disclosed in document EP 0 147 036 A.

BRIEF SUMMARY OF THE INVENTION

The invention, as indicated in the claims, has the object of specifying a switching point of the type mentioned, which can be opened and closed quickly and with low energy consumption.

In the closed state of the switch closes a disk-shaped bridge bridge piece two fixed contact pieces in the rated current direction short. The bridge switching piece is arranged rotatably about its own, perpendicular to the nominal direction extending central axis. The eddy currents necessary for the formation of a force pair of an electrodynamic rotary contact drive are induced in the movable bridge contact.

The energy to be applied for the rotational movement of the bridge switching piece is lower than in the case of translationally moving contact pieces of comparable switching points. This reduces the energy required for opening and closing the switch point.

The switching point with the rotationally moving contact piece can be optimally utilized dielectrically, since the fixed contact pieces can be made rounder than switch points with translationally moving contact pieces.

When opening two contact gaps, which are each bridged by one of two connected in series partial arcs. By this series connection of partial arcs, the voltage drop across a contact arrangement of the switching point increases arc voltage, which in turn can be commutated particularly quickly and effectively at a possible parallel path.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

eine Ansicht einer Schaltstelle nach der Erfindung im geschlossenen Zustand mit zwei feststehenden Schaltstücken und einem dazwischenliegenden Brückenschaltstück,

Fig. 2

eine Ansicht in Pfeilrichtung auf einen entlang II-II geführten Schnitt durch die Schaltstelle nach Fig.1 in geschlossenem Zustand beim Öffnen der Schaltstelle,

Fig. 3

eine Ansicht auf die Schaltstelle nach Fig.2 in geöffneten Zustand beim Schliessen der Schaltstelle,

Fig. 4

eine Ansicht in Pfeilrichtung auf einen entlang IV-IV geführten Schnitt durch ein feststehendes Schaltstück der Schaltstelle nach Fig. 3, und

Fig. 5

eine schematische Darstellung der Steuerelektronik zum Steuern der Schaltstelle nach Fig. 1.

An embodiment of the invention and the advantages achieved thereby are explained in more detail with reference to drawings. Hereby shows:

Fig. 1

a view of a switching point according to the invention in the closed state with two fixed contact pieces and an intermediate bridge contact piece,

Fig. 2

a view in the direction of arrow on a guided along II-II section through the switching point of Figure 1 in the closed state when opening the switching point,

Fig. 3

a view of the switching point of Figure 2 in the open state when closing the switching point,

Fig. 4

a view in the arrow direction on a guided along IV-IV section through a fixed contact piece of the switching point of FIG. 3, and

Fig. 5

a schematic representation of the control electronics for controlling the switching point of FIG. 1st

WAY FOR CARRYING OUT THE INVENTION

In all figures, like reference numerals refer to like-acting parts.

Fig. 1 shows an embodiment of the inventive switching point of a high or medium voltage switch for a rated current I _N in the range of 10 to some 1 '000 A.

The fixed contact pieces 1 and 2 form in the closed state of the switching point together with the electrically conductive bridge contact piece 3, the rated current path I _N. The bridge contact piece is disc-shaped and fitted between the two fixed contact pieces. The bridge contactor 3 is rotatably mounted about the central axis A normal to the nominal current direction I _N. The bridge switching piece 3 is made of a light metal, in particular aluminum. The contact points to the fixed contact pieces 1 and 2 are preferably formed from good electrical contact materials, such as silver. The distance between the fixed contact pieces 1 and 2 is 10 to a few 10 mm.

The cross section normal to the rated current direction of the bridge contact piece 3 is determined by the rated current I _N and by the current density allowed in the bridge contact block. The length in the rated current direction and thus the distance between the two fixed contact pieces 1 and 2 is determined by the maximum occurring during operation voltage and the existing insulating medium. Possible insulating media are air or SF ₆ at atmospheric or elevated pressure.

In order to move the bridge switching piece 3, an electrodynamic drive consisting of two coils 5 and 6 is provided. The first coil 5 is provided for opening the switching point, the second coil 6 for closing the switching point. The coils comprise the bridge contactor 3 and include several (for example 6-8) turns.

The coil for opening the switching point 5 is guided on one side of the central axis A below and on the other side above the bridge switching piece. These two coil sections 5 ₁ and 5 ₂ extending parallel to the center axis A are not mechanically connected to the bridge contact piece 3 and are also electrically insulated from it. In order to ensure optimum drive with the least possible energy, the coil sections 5 ₁ and 5 ₂ in the closed state of the switching point as close to the bridge contact piece 3 and in the region of the stationary contact pieces 1 and 2 facing ends of the bridge contact piece 3 are arranged.

The coil for closing the switching point 6 is also guided on one side of the central axis A above and on the other side below the Brückenschaltstücks. These two parallel to the central axis A coil sections 6 ₁ and 6 ₂ are also not mechanically connected to the bridge contact piece 3 and electrically insulated from this. In order to ensure optimum drive with the least possible energy, the coil sections 6 ₁ and 6 _{2 are arranged} in the open state of the switching point as close as possible to the bridge contact 3 and also in the region of the ends of the bridge contact 3.

The two coils 5 and 6 are formed substantially mirrored with respect to the bridge contact piece and arranged rotatably offset about the central axis A. The coil sections 5 ₁ and 6 ₁ and 5 ₂ and 6 ₂ essentially limit the rotational range of movement of the bridge contact piece 3. The coils 5 and 6 may be formed so wide that they act practically on the whole bridge contact. The coil 5 may extend, for example, in the width of the fixed piece of scarf 1 to the axis of rotation A.

The entire switching point is held together by insulating bodies 7, in particular, in each case a fixed contact piece 1 rsp. 2 with the corresponding coil sections on the same side of the bridge switching piece 5 ₁ and 6 ₂ rsp. 5 ₂ and 6 ₁ firmly connected by means of an insulating body 7.

For driving the coils 5 and 6, a power electronic control unit 9, as shown in Fig. 5, is provided. The control unit 9 essentially contains a charging device Q, one drive capacitor C _O rsp per coil. C _S and each a thyristor T _O rsp. T _S. To improve the drive efficiency can also ever a freewheeling diode D _O rsp. D _{s be} inserted in the drive circuit. Of course, other, more complex circuits for the control unit 9 come into question. Such circuits can sometimes be found in the aforementioned application EP 99810596.9.

The opening operation of the switching point is shown in Fig. 2. The bridge switch 3 is fitted between the fixed contact pieces. To trigger the opening movement of the bridge contact piece 3, the drive capacitor C _{O is} discharged via the coil 5. The resulting drive current I _O is typically a half-wave with a few 1000 A peak current at a frequency of a few 1000 Hz. As can be seen from FIG. 2, the drive current flows in the lower coil section 5 ₁ backwards (I _O1 ) and in the upper coil section 5 ₂ forward (I _O2 ). In this case 3 eddy currents are induced in the still flown through by the rated current I _N bridge contact piece, which are directed essentially opposite to the drive current. The eddy currents I _P1 caused by the backward-flowing drive current in the lower coil section I _O1 thus flow forwards, the eddy currents I _P2 caused by the forwardly flowing drive current in the lower coil section I _O2 to the rear. During the duration of the current flow in the coil, there is a repulsive force effect between the coil sections 5 ₁ and 5 ₂ and the bridge switching piece 3. The resulting force pair F _O1 and F _O2 sets the bridge switching piece 3 in a clockwise rotational movement. The bridge switching piece 3 dissolves to form two arcs of the fixed contact pieces 1 and 2 and moves rotationally about the central axis A. After a certain angle of rotation, the bridge contact piece is first braked by a mechanical braking and holding device 4, for example by mechanical friction and then held. Thus, the switch has reached the open state. The angle of rotation is dictated by the dielectric strength to be achieved and is in the range of 30-90 °, preferably about 60 °.

In order to prevent the formation of eddy currents in the fixed contact pieces 1 and 2, the contact pieces in the bridge contact piece facing area with Slots 8 provided. A fixed contact piece 1 with slots 8 is shown in Fig. 4. The slots 8 are longer than the penetration depth of the magnetic field of the drive current in the material of the fixed contact piece 1. Thus, the formation of eddy currents in the fixed contact pieces can be avoided.

The closing process of the switching point is shown in Fig. 3. The bridge switching piece 3 is held by the holding device 4. To trigger the closing movement of the bridge contact piece 3, the drive capacitor C _{S is} discharged via the coil 6. The resulting drive current I _S is typically a half-wave with several 1,000 A peak current at a frequency of a few 1,000 Hz. As can be seen from FIG. 3, the drive current flows in the lower coil section 6 ₂ to the rear (I _S2 ) and in the upper coil section 6 ₁ forward (I _S1 ). Here again eddy currents are induced in the bridge contact piece 3, which are directed essentially opposite to the drive current. The eddy currents I _T2 caused by the backward-flowing drive current in the lower coil section I _S2 thus flow forwards, the eddy currents I _T1 caused by the forwardly flowing drive current in the lower coil section I _S1 to the rear. During the duration of the current flow in the coil there is a repulsive force effect between the coil sections 6 ₁ and 6 ₂ and the bridge contact piece 3. The resulting force pair F _S1 and F _S2 sets the bridge contact piece 3 in a counter-clockwise rotational movement. The bridge contact piece 3 releases from the holding device 4 and rotates around the central axis A. The bridge contact piece 3 rotates until it is decelerated by the fixed contact pieces and then held. The switching point is closed again and the rated current I _N flows through the bridge contact piece 3.

NAME LIST

1.2

Fixed contact pieces

3

Bridging contact member

4

holder

5

Drive coil for opening the switching point

5 ₁ , 5 ₂

Coil sections extending parallel to the central axis

6

Drive coil for closing the switching point

6 ₁ , 6 ₂

Coil sections extending parallel to the central axis

7

insulation body

9

Power electronic control unit

A

Central axis, axis of rotation

C _O , C _S

drive capacitors

D _O , D _S

Freewheeling diodes

F _O1 , F _O2

Force on bridge contact when opening the switching point

F _S1 , F _S2

Force on bridge contact piece when closing the switch point

I _N

Current direction

I _O1 , I _O2

Drive current for opening the switch point

I _P1 , I _P2

Induced eddy currents when opening the switch point

I _S1 , I _S2

Drive current for closing the switching point

I _T1 , I _T2

Induced eddy currents when closing the switch point

Q

loader

T _O , T _S

thyristor

Claims (5)

1. Switching point for a high- or medium-voltage switch, containing

   - two fixed contact members (1, 2),

   - a moving, electrically conductive bridging contact member (3) which, when the switching point is closed, is fit in between the fixed contact members (1, 2) and short-circuits them in the rated current direction (I_N), and

   - a drive for moving the bridging contact member (3), which comprises at least two coils (5, 6), which are arranged such that they at least partially bound the movement range of the bridging contact member (3), and a power-electronic control unit (9) for supplying the coils (5, 6), being

   - the fixed contact members (1, 2) are designed and arranged essentially symmetrically with respect to one another with respect to a centre axis (A) of the bridging contact member (3) running at right angles to the rated current direction (I_N), characterized in that

   - the bridging contact member (3) is arranged such that it can rotate about the centre axis (A) in order to open and close the switching point.
2. Switching point according to Claim 1, characterized in that

   - the bridging contact member (3) is extended in the form of a plate in the rated current direction (I_N) and in the direction of the centre axis (A).
3. Switching point according to Claim 1, characterized in that

   - two coil sections (5₁, 5₂), which are electrically insulated form the bridging contact member (3) and run parallel to the centre axis (A), of a first of the two coils (5) are each arranged, with respect to the bridging contact member (3) when the switching point is closed,

   - in the region of opposite ends of the bridging contact member and

   - offset on opposite sides of the bridging contact member (3) in the opposite direction to the direction in which the bridging contact member rotates during opening of the switching point,

   and in that

   - two coil sections (6₁, 6₂), which are electrically insulated from the bridging contact member (3) and run parallel to the centre axis (A), of the second coil (6) are each arranged, with respect to the bridging contact member (3) when the switching point is open,

   - in the region of opposite ends of the bridging contact member and

   - offset on opposite sides of the bridging contact member (3) in the direction in which the bridging contact member rotates during opening of the switching point.
4. Switching point according to one of Claims 1 or 2, characterized in that

   - a holding apparatus (4) for fixing the bridging contact member (3) in the open state of the switching point is arranged in the region of the coil (6) which bounds the movement range of the bridging contact member (3) during opening of the switching point.
5. Switching point according to one of Claims 1 to 3, characterized in that

   - the fixed contact members (1, 2) each have at least one slot (S) which runs away from the bridging contact member (3) in the rated current direction.

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