DE3116543A1 - Pantograph isolating switch - Google Patents

Abstract

Pantograph isolating switches are a moving connecting element between two conductor tracks and, as a rule, consist of two lever rods which are connected by means of a connecting joint and can move with respect to one another in the form of a pantograph. They have a static contact pressure and an additional dynamic contact pressure which is generated by the electromagnetic forces of the short-circuit current. Since the short-circuit current is initially very large and subsequently reduces, there is initially a powerful increase in the contact pressure and, subsequently thereto, the components swing back with a severe reduction in the contact pressure which can cause destruction of the contact system. In the pantograph isolating switch according to the invention, the occurrence of dangerous oscillations is prevented in that the current flow is distributed asymmetrically onto the moveable lever rods. Correspondingly constructed moving contact points result in an approximately symmetrical current distribution being ensured in the main contact system itself.

Description

Scissor disconnector

The invention relates to a scissor disconnector with two connected by a connecting hinge and movable to one another in the form of scissors Lever rods, which serve as connecting elements between two conductor tracks.

High-voltage disconnector that closes the isolating distance with a scissor-like bridge movable lever linkage arrangement and the one at the isolating distance for current management necessary contact pressure of the contact pieces by elastic bending of the as Electric conductors serving levers of each lever linkage are in the area the neighboring, traversed by the current in the same direction Conductors exposed to the attractive forces of electricity. The neighboring conductors pull themselves under the action of the forces that occur in a dynamic short circuit very strongly during the first current half-waves. With the decay of the direct current link and the associated reduction in the attractive forces, the conductors spring, So the individual levers of each lever linkage, back, overshoot theirs Starting position and thus reduce the contact force or, under certain circumstances, cause the Contact point a lifting of the contact pieces.

Any opening of the circuit breaker contact while the current is flowing creates an electric arc which, with its large amount of heat, affects the material liquefied at the point of contact. After the power has been switched off, the isolating switch is on then either welded at the contact point, i.e. no longer switching normally, or the contact point is damaged by the burn to such an extent that the device has its Can no longer carry rated current.

The object of the invention is to create a scissor disconnector, in which the disadvantages of the known isolators are avoided. In particular, should Destruction at the contact point can be avoided.

According to the invention, this object is achieved in that one of the two Lever linkage compared to the other is designed with high resistance.

The fact that one of the two lever linkages of a much smaller one Electricity, e.g. 1% of the total current flows through it, becomes the electromagnetic force between the two lever rods to a fraction of the force with even Distribution of the current e.g. with a current ratio of 1: 100 to a force of 4% reduced.

The second lever linkage is advantageously designed so that through Installation of insulating elements, the current flow is interrupted.

A suitable design of the device according to the invention provides that in the area of the lever linkage that is not traversed by electricity, the isolation takes place in the area of the central joint.

It is also advantageous to have current transitions in the area of the universal joint from the lever linkage through which current flows to the lever linkage through which there is no current provide that causes an even flow of current in the area of the contact system.

When designing the insulation of the lever linkage through which no current flows it should be noted that it is advantageous to dimension the insulation so that also under unfavorable external influences and occurrence of a short circuit with a large Voltage drop in the lever linkage no flashover or other damage to the Isolation takes place.

The high-resistance design of the second lever linkage leads to that the electromagnetic forces between the two lever rods by at least can be reduced by an order of magnitude and thus a prevention of mechanical Vibrations in the event of a short circuit is caused.

The need to use devices for cushioning Such vibrations, as described, for example, in laid-open specification 23 36 543 is omitted.

The fact that from the universal joint up to the mating contact of the Current is divided between the two halves of the contact system, but becomes one Increasing the contact pressure in the event of a short circuit causes it to the invention Scissor disconnector permitted, with the usual number of contact points and the normal contact pressure to control the largest short-circuit currents.

With the aid of the drawing, an exemplary embodiment of the invention is intended to be in more detail explained.

It shows Figure 1 a circuit breaker with scissors-like movable Lever linkage in the switched-on state, FIG. 2 a disconnector according to FIG an isolated half of the lever linkage, Figure 3 is a schematic representation the power transmission device in the universal joint, Figure 4 shows a circuit breaker according to Figure 2 with a power transmission device below the universal joint.

A scissor disconnector basically consists of two lever rods (1) and (3), which at points (7) and (8) are stationary and articulated on one not further illustrated bearing block (8a) are attached. The lever linkage (1) consists from a first lever (la) (upper beam) and a second lever (ib) (lower beam), which are connected to one another by means of a joint (2). The lower end of the Lever (lb) is connected to the bearing block (8a) at point (8), while the after The end of the lever (la) pointing upwards is bent inwards at an obtuse angle is.

The lever linkage (3) consists in the same way of two levers (3a) and (3b) which are connected to one another by means of a joint (4). The lever chants (3) is also articulated to the bearing block (8a) at point (7). The top The end of the lever (3a) is slightly bent inwards. The two lever linkages (1) and (3) are above the two joints (2) and (4) at the connection point (5) with one another articulated, the levers (la) and (3a) crossing. That so formed upwardly pointing end of the scissor disconnector, shown in FIG. 1 in a V-shape takes a conductor (5), which is at a certain distance above the bearing block (8a) is located. If now, due to a switching movement, the levers (lb) and (3b) respectively rotated in the directions indicated by arrows A and B moves the connection point (5) down and the two ends of each lever linkage turned sideways and also downwards in the direction of C and D.

The lever linkages <1) and (3) themselves are used for scissor disconnectors the previously known design as an electrical connecting conductor from the conductor (6) up to a connection on the bearing block (8a). The direction of the current runs in parallel. If a short circuit now occurs, the two lever rods (1) and (3) at; in the process, they are set into vibrations, the amplitudes of which occur in the left lever linkage (3) are shown (Figure 1). The furthest inward position of the lever linkage (3) is labeled (10) and the furthest one is labeled (9). With (9) and (10) designated positions arise due to elastic deformation of overshoot. This will pull the upper end of the rebel rod away from the ladder (6) UnQ withdraw the amount. This occurs between the conductor (6) and the contact pieces an arc occurs at the upper end of the lever linkage, which then leads to damage the contact pieces leads.

FIG. 2 now shows a scissor disconnector in which the lever linkage (3) an insulation (3c) is used in the area of the joint (4), which prevents the flow of current prevented by the lever (3). The continuous current as well as the short-circuit current can only flow through the lever linkage (1), so that even in the event of a short circuit, none electromagnetic forces between the two lever rods and therefore none Vibrations occur. All the advantages of the scissor disconnector in terms of its own symmetrical, mechanical structure and the electromagnetic contact pressure increase due to the parallel current flow from the contact (6) to the universal joint (5) obtain.

Figures 3 and 4 now show some examples of the design of the Current transfer from the lever linkage (1) to the one above the insulation Components of the lever linkage (3).

In Figure 3 it is shown how the two components (lla) and (alb) of the connecting joint (5) can be formed, for example.

In the present example, they are the father piece (lla) and mother piece (alb) executed, the sliding elements arranged in an annular gap (12) and guide elements (13) are connected to one another. Is in the axis of rotation a connection element (14) secures against the separation of the two elements (lla) and (body) provided. A component (15) seals against against external influences. The two parts (11a) and (11b) are shown partially in section. Between the contact pieces (16a) arranged above the connecting joint (5) and (16b) the contact (6) of the upper conductor track is clamped. The contact pieces (16a) and (16b) can also lie one behind the other? they are here for improvement shown side by side for clarity. The same goes for the levers (la) and (3a).

Figure 4 shows how, for example, an additional contact system (17) with a block contact (18) a finger holder (19) and two contact fingers clamped therein (20a) and (20b) is arranged.

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Claims (8)

Claims O scissor disconnector with two by a connecting hinge connected and scissor-like to each other movable lever rods, which as mechanical Actuating elements are used for the contact system, characterized in that the a lever linkage as an electrical connection conductor between the two conductor tracks low resistance and the other lever linkage at least partially executed high resistance is. 2. Schrader disconnector according to claim 1, characterized in that in a part of the <3c> lever linkage, which is not used for electrical connection Components made of insulating material are inserted. 3. Scissors disconnector according to one of the preceding claims, characterized characterized in that in the area of the connecting joint between the two lever rods a low-resistance electrical connection is arranged. 4. Scissors disconnector according to one or more of the preceding Claims, characterized in that between the two upper levers (la) and (3a) a low-resistance electrical that closes or opens during the switching process Connection is arranged. 5. Scissor disconnector according to one or more of the preceding Claims, characterized in that above the joints (2) and (4) an electrical conductive connection that opens when the disconnector is switched off is provided and the two lever linkages (Ij and (3) in the area of the connecting joint (5) against each other are electrically isolated. 6. Scissor disconnector according to one or more of the preceding Claims, characterized in that the electrical connection between the two Lever rods (1) and (3) in the area of levers (la) and (3a) are designed to be short-circuit proof is. 7. Scissor disconnector according to one or more of the preceding Claims, characterized in that the electrical connection between the levers (la) and Oa) is designed as a contact system, which is made in a manner known per se a block, spherical or ring-shaped contact element on the one hand and at least one there is mating contact containing two fingers. 8. Scissor disconnector according to one or more of the preceding Claims, characterized in that the arranged between the levers (la) and (3a) Contact system has at least two point contact points.