Patent Grant
6884952
The invention relates to the field of high-voltage switching technology, in particular to contact fingers, such as those used in high-power switchgears, in particular, in disconnectors. It relates to a contact finger module, to a disconnector module and to a high-power switchgear.
Contact finger modules are known from the prior art, which comprise a leaf spring that extends along a longitudinal direction and a contact finger, having a contact piece and a flexible contact piece support which extends along a longitudinal direction. Contact finger modules such as these are used in disconnector modules in high-power switchgears, for example generator switches, in order to make contact with the isolator tube.
At an end which faces away from the attachment end of the contact finger, the contact piece projects beyond the flexible contact piece support in the opposite direction to the deflection direction, which is aligned essentially at right angles to the longitudinal direction. The flexible contact piece support and the contact piece are connected to one another by means of a screw connection, which runs through the flexible contact piece support and centrally into the contact piece. An isolating platelet which is arranged on the side of the flexible contact piece support facing away from the contact piece is arranged between the contact piece support and the head of the screw of the screw connection and extends in the longitudinal direction, beyond the contact piece, in the direction of the attachment end.
The leaf spring is curved in the form of an arc over virtually its entire length and, in the mounted state, extends from the attachment end in the longitudinal direction to a point in front of the contact piece and as far as the isolating platelet. In the mounted state, the leaf spring rests on the isolating platelet such that the leaf spring can produce a force which counteracts any deflection of the contact piece in the deflection direction, without any current flowing through the leaf spring into the contact piece. At the end of the leaf spring which rests on the isolating platelet, the leaf spring has a bend which continues away from the flexible contact piece support, resulting in the production of an end of the leaf spring which, in the mounted state, includes an angle of about 20° with the longitudinal direction and continues away from the contact piece support.
A contact finger module such as this has the disadvantage that the field control is poor, since the contact piece and the flexible contact piece support, as well as the head of the screw of the screw connection as well as the end of the leaf spring which continues away from the contact piece support lead, at the contact-making end, which faces away from the attachment end, to a non-uniform field distribution with strong electrical fields at the edges and ends of the contact finger module.
The object of the invention is therefore to provide a contact finger module of the type mentioned initially which does not have the disadvantages mentioned above.
One particular aim is to achieve good field control in the area of the contact pieces.
This object is achieved by apparatuses having features described herein.
The contact finger module according to the invention for mounting in a high-power switchgear includes:
The contact finger module according to the invention is characterized in that when in the mounted state, the leaf spring extends in the longitudinal direction at least as far as the center of the extension of the contact piece in the longitudinal direction.
This results in improved field control in the area of the contact pieces. Field strength peaks which are arranged at the corners or edges of the contact finger module close to the contact-making end are at least partially shielded. The risk of electrical flashovers is reduced.
Instead of being used exclusively only to produce a sufficient contact pressure of the contact piece on a further contact piece which, together with it, forms a detachable electrical contact, the leaf spring additionally carries out field control tasks.
In one preferred embodiment of the subject matter of the invention, in the mounted state, the leaf spring extends in the longitudinal direction at least as far as the end of the extension of the contact finger in the longitudinal direction. This results in even better field control.
In a further preferred embodiment of the subject matter of the invention, the point at which the force is introduced from the leaf spring into the contact finger is located, with respect to the longitudinal direction, in the center of the extension of the contact piece in the longitudinal direction, or on the side of this center facing away from the attachment end.
The leaf spring thus produces a relatively large contact pressure (large contact force, on the contact piece with a relatively small bias stress, and this contact pressure can be exerted by the pressure of the leaf spring on the contact finger by the contact piece.
In a further, particularly preferred embodiment of the subject matter of the invention, the leaf spring projects beyond the contact finger in the longitudinal direction in the mounted state. This results in particularly good field control by the leaf spring.
In a further advantageous embodiment, the leaf spring is bent in the opposite direction to the deflection direction at the end facing away from its attachment end, or is bent through at least 180° in the deflection direction. In this way, field peaks which may occur on exposed edges of the leaf spring are largely avoided, thus resulting in a largely homogeneous field distribution and correspondingly good field control.
The leaf spring is particularly advantageously bent through at least 180°, in particular through more than 185°, in the opposite direction to the deflection direction at its end facing away from its attachment end. In this way, field peaks which may be formed on exposed edges of the leaf spring are avoided particularly well, thus resulting in a largely homogeneous field distribution and correspondingly particularly good field control.
In the unmounted state, the leaf spring is advantageously not curved between its ends. In particular, it is also not curved at its attachment end. A leaf spring such as this can be produced reproducibly and easily, that is to say tight tolerances can be specified, and it is possible to achieve only a small amount of scatter in the contact forces.
Nevertheless, a leaf spring such as this can exert a sufficiently large force on the contact finger.
The flexible contact piece support very advantageously includes a lamella stack composed of electrically conductive lamellae. Silver-plated copper lamellae, in particular with thicknesses of between 0.1 mm and 0.7 mm, and preferably between 0.15 mm and 0.3 mm, are advantageously used.
The contact piece support is particularly advantageously arranged above the contact piece in the deflection direction, with the contact piece support and the contact piece being fixed to one another by means of a radial rivet. In comparison to the known screw connections between the contact piece and the flexible contact piece support, a radial rivet (which is also referred to as a swiveling joint) has long-term stability, thus resulting in better constancy of the contact pressure over a large number of opening/closing cycles of a contact which is produced by means of the contact finger module. Furthermore, the swiveling joint is a captive joint.
One embodiment of the subject matter of the invention, in which the contact finger module has two or three contact fingers each having at least one contact piece and each having at least one flexible contact piece support is particularly advantageous, with the contact piece support having a common attachment end, and having two or three leaf springs which have a common attachment end with in each case one leaf spring interacting with each contact finger such that the leaf spring can produce a force which counteracts any deflection of the contact piece of the contact finger in the deflection direction; and with each leaf spring extending, in the mounted state, in the longitudinal direction at least to the center of the extension of the respective contact piece in the longitudinal direction.
Two or three leaf springs are thus in each case formed in one, preferably integral, component, and two or three contact fingers are in each case combined in one component, which may be integral. However, the component which includes the contact fingers advantageously has two or three contact pieces, and one component has the two or three flexible contact piece supports. The latter component may, for example, be integral or, in the case of a lamella stack, the individual lamellae of the two or three flexible contact piece supports are advantageously formed integrally.
This simplifies the installation of the contact fingers, making it possible to simplify the production of the contact finger module.
The high-power switchgear according to the invention with a large number of contact finger modules which act as part of a detachable electrical contact is characterized according to the invention by having contact finger modules. The advantages are those mentioned above. The contact finger modules are preferably used in the rated current circuit and/or in the disconnector of the high-power switchgear. Typical rated currents and voltages which are switched by a high-power switchgear such as this are between 6 kA and 40 kA at 1 kV to 50 kV.
The disconnector module according to the invention for a high power switchgear has at least one drive housing and a moveable disconnector tube, and has a large number of contact finger modules which are arranged on the drive housing or on the disconnector tube and act as part of a detachable electrical contact between the disconnector tube and the drive housing. This is characterized by having contact finger modules according to the invention. The advantages are the same as those stated above.
Further preferred embodiments and advantages will become evident from the dependent patent claims and from the figures.
The subject matter of the invention will be explained in more detail in the following text with reference to preferred exemplary embodiments which are illustrated in the attached drawings, in which:
The reference symbols used in the drawings and their meaning are listed in summarized form in the list of reference symbols. In principle, identical parts or parts having the same effect are provided with the same reference symbols in the figures. The described exemplary embodiments represent examples of the subject matter of the invention and have no restrictive effect.
Approaches to Implementation of the Invention
The disconnector tube 11 is used to produce a visible isolating gap. The disconnector tube 11 can be moved by means of a drive 12, which is indicated schematically, along an axis which runs parallel to a longitudinal direction x that is illustrated in FIG. 1. When the disconnector module is in the closed state as shown in
In order to produce the visible isolating gap, the disconnector tube 11 is moved in the opposite direction to the longitudinal direction x, so that the contact finger modules 1 which are on the arcing chamber drive housing side no longer make electrical contact with the disconnector tube 11, and a sufficient gap is produced between the drive chambers 10a, 10b. In the closed state, the leaf springs 3 produce a contact pressure which pushes the contact pieces 4 against the disconnector tube 11.
In order to close the disconnector module, the disconnector tube 11 is moved in the longitudinal direction x, so that both the contact finger modules 1 which are on the disconnector drive housing side and the contact finger modules 1 which are on the arcing chamber drive housing side make contact with the disconnector tube 11.
As can be seen from
During closure of the disconnector module, all of the contact pieces 4 are deflected along a deflection direction which points radially outward and is thus aligned at right angles to the longitudinal direction x. Contact forces to produce suitable contact pressures are typically between 20 N and 40 N per contact piece 4, in particular between 25 N and 35 N. Corresponding prestressing forces per contact piece 4 are typically between 10 N and 20 N, in particular between 12 N and 18 N.
A high-power switchgear according to the invention may include an disconnector module such as that illustrated in
Contact finger modules 1 according to the invention can also be used at other switching points or contact points in high-power switchgears, for example in the arcing chamber or in some other way preferably in the rated current circuit, in particular in conjunction with wear-resistant contact parts.
The contact piece support 5 is connected to the contact piece 4 at a further end 52 of the contact piece support 5, which is referred to as the contact-making end 52. This projects beyond the contact piece support in the opposite direction to the deflection direction z. The connection between the contact piece support 4 and the contact piece 4 is advantageously formed by a swiveling joint 6, which is also referred to as a radial rivet 6. Other form-fitting, interlocking or integral connections are also possible. A washer 6a may be arranged between the flexible contact piece support 5 and the head of the radial rivet 6.
The contact piece 4 is used to make contact with a second contact piece which is not illustrated but can move relative to the contact finger module 1 along the longitudinal direction x, and can form a detachable electrical contact with the contact piece 4 (in the closed state). In the configuration shown in
The flexible contact piece support 5 is advantageously in the form of a lamella stack. The lamellae are composed of a material of high electrical conductivity and may have an electrically conductive coating. The lamellae are preferably produced from copper and advantageously have a silver coating. The individual lamellae are advantageously identical and have a typical thickness of between 0.1 mm and 0.7 mm, preferably between 0.15 mm and 0.3 mm. This makes it possible to achieve a suitable elastic deformation capability for the flexible contact piece support 5, with high electrical conductivity.
The preferably metallic, in particular steel, leaf spring 3 is arranged on the side of the flexible contact piece support 5 which faces away from the contact piece 4. Except at its end 32, it is not curved and advantageously extends, as is illustrated in
The bending through more than 180° results in secure contact between the leaf spring 3 and the contact finger 2, and a long lever arm for the leaf spring 3. With regard to the longitudinal direction x, the contact point of the leaf spring 3, or the point at which the force is introduced, for a longitudinal coordinate which is referred to as xF and is further away from the attachment end 31 than the longitudinal coordinate x1, is located at the center of the contact piece 4.
The leaf spring extends as far as the longitudinal direction coordinate xL in the longitudinal direction x.
In
The contact piece 4 does not necessarily end flush with the contact-making end 52 of the contact piece support 5 in the longitudinal direction x, as is illustrated in FIG. 2. The contact piece 4 may project beyond the contact piece support 5 in the longitudinal direction x, or vice versa. The contact piece 4 is, however, arranged at the contact-making end 52 of the contact piece support 5, and its longitudinal extension is a good measure for the size of the contact finger module 1. A good field control effect by the leaf spring 3 is achieved just by the leaf spring 3 extending in the longitudinal direction x at least to the center x1 of the extension of the contact piece 4 in the longitudinal direction x.
There is no need for the leaf spring 3 to be supported on an isolation platelet instead of directly on the contact finger 2. Experiments and simulations have shown that path currents which flow through the leaf spring 3 from the attachment end 31 through the leaf spring 3 into the contact-making end 52 of the contact finger 2 do not lead to the leaf spring 3 being heated to such an extent that it loses its spring force to any relevant extent.
The leaf spring 3 may also be bent in the direction of the deflection direction z (not illustrated). In this case, bending through at least 180°, and if possible also greater than or equal to 270°, is advantageous in order to achieve good field control. If the leaf spring 3 is bent at its end 32 in the direction of the deflection direction z, the leaf spring 3 may advantageously be bent in the opposite direction to the deflection direction z between its ends 31, 32 and/or may extend in the opposite direction to the deflection direction z there (partially as well), and spacing means (not illustrated) may advantageously be arranged between the leaf spring 3 and the contact piece support 5 at the attachment end 31, 51, in order to make it easier for the leaf spring 3 to exert the contact pressure on the contact finger 2.
The contact finger module 1 shown in
The respective two contact fingers 2, 2′ and the two leaf springs 3, 3′ are advantageously identical and advantageously also have the same effect. A contact finger 2 may be formed from two or more pieces, or else may be integral. Currents which flow continuously through a contact finger 2 in the closed state are typically between 80 A and 200 A, in particular between 100 A and 160 A. A contact finger module 1 which has two contact fingers 2, 2′ carries currents that are twice as great, in a corresponding manner.
In the transverse direction that is annotated y in
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