EP1180776A1 - 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

The invention is based on a switching point of a high or Medium-voltage switch according to the preamble of claim 1.

Such switches are in the high or medium voltage level as mechanical On switch or as mechanical off switch with an arc duration of used at most a few 100 µs.

STATE OF THE ART

Such a switching point is in the older European patent application Case number 99810596.9.

The switching point of a high or medium voltage switch contains two fixed ones Switch pieces, which are cylindrical and coaxially one inside the other form an annular gap. A movable, designed in the form of a contact ring Bridge switching piece is in the closed state of the switching point in the ring-shaped Gap fitted. On both sides of the contact ring are coils of an electrodynamic Drive arranged to move the contact ring in the axial direction.

To open the switching point, a current is fed into one of the two coils. in the Eddy currents are induced in the contact ring, which essentially correspond to the current in the Are directed in opposite directions. This causes the coil and contact ring to come into contact each other, resulting in translational acceleration of the contact ring and thus leads to the opening of the switching point.

To close the switching point, the current flows into the other of the two coils fed, whereupon the contact ring moves back to the starting position and the switching point is thus closed again.

SUMMARY OF THE INVENTION

The object of the invention is as set out in the claims based on specifying a switching point of the type mentioned, which quickly and can be opened and closed with little energy.

When the switching point is closed, a disc-shaped one closes Bridge contact piece two fixed contact pieces short in nominal current direction. The Bridge contact is around its own, perpendicular to the nominal current direction Center axis rotatably arranged. The one to form a pair of forces electrodynamic, rotary contact drive necessary eddy currents induced in the movable bridge contact.

The energy to be applied for the rotary movement of the bridge contact is less than with translationally moving contact pieces of comparable switching points. This reduces the energy required to open and close the Switching.

The switching point with the rotating moving contact piece can be dielectric make optimal use of it, since the fixed contact pieces are made rounder can be used as switching points with translationally moved contact pieces.

When opening, two contact gaps are created, each of one of two in series switched partial arcs are bridged. Through this series connection of Partial arcs increase the falling at a contact arrangement of the switching point Arc voltage, which in turn is particularly useful in the event of a parallel path can be commutated quickly and effectively.

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 which can be achieved thereby are explained in more detail below with reference to drawings. Here shows:

Fig. 1

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

Fig. 2

2 shows a view in the direction of the arrow on a section through II-II through the switching point according to FIG. 1 in the closed state when the switching point is opened,

Fig. 3

2 shows a view of the switching point according to FIG. 2 in the open state when the switching point is closed,

Fig. 4

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

Fig. 5

2 shows a schematic illustration of the control electronics for controlling the switching point according to FIG. 1.

WAY OF CARRYING OUT THE INVENTION

In all figures, the same reference numerals refer to parts having the same effect.

1 shows an embodiment of the switching point according to the invention of a high or medium voltage switch for a nominal current I _N in the range from 10 to a few 1,000 A.

In the closed state of the switching point, the fixed contact pieces 1 and 2 together with the electrically conductive bridge contact piece 3 form the nominal current path I _N. The bridge contact is disc-shaped and fitted between the two fixed contact pieces. The bridge contact piece 3 is rotatably mounted about the central axis A normal to the nominal current direction I _N. The bridge contact 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, for example silver. The distance between the fixed contact pieces 1 and 2 is 10 to a few 10 mm.

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

In order to move the bridge contact 3, there is an existing of two coils 5 and 6 electrodynamic drive provided. The first coil 5 is for opening the Switching point, the second coil 6 is provided for closing the switching point. The Coils include the bridge contact 3 and contain several (e.g. 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 contact. These two coil sections 5 ₁ and 5 ₂ running parallel to the central axis A are not mechanically connected to the bridge contact 3 and are also electrically insulated from the latter. In order to ensure optimal drive with as little energy as possible, the coil sections 5 ₁ and 5 _{2 are arranged} as close as possible to the bridge contact 3 and in the region of the ends of the bridge contact 3 facing the fixed contact ₁ and ₂ when the switching point is closed.

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 bridge contact. These two coil sections 6 ₁ and 6 ₂ running parallel to the central axis A are likewise not mechanically connected to the bridge contact 3 and are electrically insulated from it. In order to ensure optimum drive with as little energy as possible, the coil sections 6 ₁ and 6 _{2 are arranged} as close as possible to the bridge contact 3 and also in the region of the ends of the bridge contact ₃ in the open state of the switching point.

The two coils 5 and 6 are essentially mirrored with respect to the bridge contact and are arranged in a rotationally offset manner about the central axis A. The coil sections 5 ₁ and 6 ₁ and 5 ₂ and 6 ₂ essentially limit the rotational movement range of the bridge contact piece 3. The coils 5 and 6 can be designed so wide that they act practically on the entire bridge contact piece. The coil 5 can extend, for example, in width from the fixed formwork piece 1 to the axis of rotation A.

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

A power electronic control unit 9, as shown in FIG. 5, is provided for controlling the coils 5 and 6. The control unit 9 essentially contains a charging device Q, a drive capacitor C _O rsp per coil. C _S and a thyristor T _O rsp. T _S. To improve the drive efficiency, a free-wheeling diode D _O rsp. D _{S be} inserted into the drive circuit. Of course, other, more complex circuits are also possible for the control unit 9. Such circuits can sometimes be found in the mentioned application EP 99810596.9.

The opening process of the switching point is shown in Fig. 2. The bridge contact piece 3 is fitted between the fixed contact pieces. To trigger the opening movement of the bridge contact 3, the drive capacitor C _{O is} discharged via the coil 5. The resulting drive current I _O is typically a half-wave with some 1,000 A current peak at a frequency of some 1000 Hz. As seen from Fig. 2 shows the driving current flows in the lower coil portion 5 ₁ backwards (I _O1) and in the upper coil section 5 ₂ forward (I _O2 ). In this case, eddy currents are induced in the bridge contact piece through which the nominal current I _{N is still} flowing, and are essentially directed in the opposite direction to the drive current. The eddy currents I _P1 caused by the drive current flowing backwards in the lower coil section I _O1 thus flow to the front, the eddy currents I _P2 caused by the drive current flowing 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 contact piece 3. The resulting pair of forces F _O1 and F _O2 sets the bridge contact piece 3 in a clockwise rotational movement. The bridge contact piece 3 detaches from the fixed contact pieces 1 and 2 with the formation of two arcs and moves rotationally around 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. The switching point has thus reached the open state. The angle of rotation is predetermined by the dielectric strength to be achieved and is in the range of 30-90 °, preferably approximately 60 °.

In order to form eddy currents in the fixed contact pieces 1 and 2 prevent the contacts in the area facing the bridge contact with Provide slots 8. A fixed contact piece 1 with slots 8 is shown in FIG. 4 shown. The slots 8 are longer than the depth of penetration of the magnetic field Drive current in the material of the fixed contact piece 1. Thus, the Avoid eddy currents in the fixed contact pieces become.

The closing process of the switching point is shown in Fig. 3. The bridge contact piece 3 is held by the holding device 4. To trigger the closing movement of the bridge contact 3, the drive capacitor C _{S is} discharged via the coil 6. The resulting drive current I _S is typically a half-wave with a few 1,000 A current peak at a frequency of a few 1,000 Hz. As can be seen from FIG. 3, the drive current flows to the rear in the lower coil section 6 ₂ (I _S2 ) and in the upper coil section 6 ₁ forward (I _S1 ). Eddy currents are again induced in the bridge contact 3, which are essentially directed in the opposite direction 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 forward, the eddy currents I _T1 caused by the forward flowing drive current in the lower coil section I _S1 . 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 3. The resulting pair of forces F _S1 and F _S2 sets the bridge contact 3 in a counterclockwise rotary movement. The bridge contact 3 detaches from the holding device 4 and rotates about the central axis A. The bridge contact 3 rotates until it is braked by the fixed contact pieces and then held. The switching point is closed again and the nominal current I _N flows through the bridge contact 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 running parallel to the central axis

6

Drive coil to close the switching point

6 ₁ , 6 ₂

Coil sections running 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 when closing the switching point

I _N

Current direction

I _O1 , I _O2

Drive current to open the switching point

I _P1 , I _P2

Induced eddy currents when opening the switching point

I _S1 , I _S2

Drive current to close the switching point

I _T1 , I _T2

Induced eddy currents when the switching point closes

Q

loader

T _O , T _S

thyristor

Claims (5)

Switching point of a high or medium voltage switch, containing two fixed contact pieces (1, 2), a movable, electrically conductive bridge contact piece (3) which is fitted in the closed state of the switching point between the fixed contact pieces (1, 2) and short-circuits them in the nominal current direction (I _N ), and A drive for moving the bridge contact (3), which comprises at least two coils (5, 6) which at least partially limit the range of movement of the bridge contact (3) and a power electronic control unit (9) for feeding the coils (5, 6), characterized in that the fixed contact pieces (1, 2) are formed and arranged essentially symmetrically with respect to one another with respect to a central axis (A) of the bridge contact piece (3) which is normal to the nominal current direction (I _N ), and that the bridge contact piece (3) for opening and closing the switching point is arranged rotatably about the central axis (A). Switching point according to claim 1, characterized in that the bridge contact (3) is extended in the form of a plate in the nominal current direction (I _N ) and in the direction of the central axis (A). Switching point according to claim 1, characterized in that two coil sections (5 ₁ , 5 ₂ ) of a first of the two coils (5), which are electrically insulated from the bridge contact (3) and run parallel to the central axis (A), with respect to the bridge contact (3) in the closed state of the switching point in the area of opposite ends of the bridge contact and counter to the direction of rotation of the bridge contact when opening the switching point offset on opposite sides of the bridge contact (3)
are arranged and that two coil sections (6 ₁ , 6 ₂ ) of the second coil (6) which are electrically insulated from the bridge contact piece (3) and run parallel to the central axis (A) with respect to the bridge contact piece (3) in the open state of the switching point in the area of opposite ends of the bridge contact and offset in the direction of rotation of the bridge contact when opening the switching point on opposite sides of the bridge contact (3)
are arranged. Switching point according to one of claims 1 or 2, characterized in that A holding device (4) for holding the bridge contact (3) in the open state of the switching point is arranged in the area of the coil (6) delimiting the range of movement of the bridge contact (3) when the switching contact is opened. Switching point according to one of claims 1 to 3, characterized in that the fixed contact pieces (1, 2) each have at least one slot (S) running away from the bridge contact piece (3) in the nominal current direction.

Images