HK1138103B - Switching arrangement - Google Patents

Description

The invention relates to a switchgear with two operating positions for switching a winding during transformer operation, whereby a passing current is switched from one current path to another current path during switching.

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This well-known switch arrangement can be used for various applications in combination with a load level switch. It is primarily used to re-polarize the control voltage in applications with a large control range, such as phase shift transformers.

In this known arrangement, two horizontal planes are usually provided for each phase to be switched. In each plane, fixed contacts are arranged around a centrally arranged, rotatable switch shaft on an insulating material frame. These fixed contacts are optional switched in each plane by an electrically conductive arc-shaped switch segment, each one fixed to the switch shaft. The adjustment of the known switch arrangement from one operating position to the other is effected by rotation of the switch shaft. The change of the operating positions requires a switch step of 120 degrees.

In the familiar switchgear arrangement, the movable switchgear has a large number of mobility-trained contact fingers or lamellae against the force of contact springs, which ensure that the movable switchgear can safely make contact with the respective fixed contact, located on the insulating material frame - even with the small, manufacturing-technically unavoidable horizontal differences.

This well-known switch arrangement has several disadvantages: first, the movable switch contact, i.e. the switch segment, with its many independently moving contact fingers, is an extremely complex component with a large number of individual parts and is therefore costly and laborious to manufacture.

Secondly, the fact that a large number of contact fingers of the movable switchgear are successively placed on the respective fixed contacts, each time with spring forces to be overcome on the respective contact fingers, requires a high torque for the operation of the central switchgear.

The two levels of function normally required per phase greatly limit a possible construction programme because of the length extension of the switch arrangement.

The geometry of the contact fingers on the control segment and the corresponding fixed contacts on the insulation frame allows only a small volume of the switching contact.

The purpose of the invention is to specify a generic circuit arrangement which no longer has these disadvantages.

This task is solved by a circuit arrangement with the characteristics of the first patent claim.

The invention shows that the movable switch contact, i.e. the arc-shaped switch segment, is formed as a simple, curved rail of electrically conductive material. There are no contact fingers, no springs, no leads - the switch segment consists only of a massive rail, preferably a copper rail; the ends of which are preferably rejuvenated to facilitate running on the fixed contacts. This rail can be simply screwed with an insulating contact support, which is in turn fixed to the switch threshold.

Furthermore, this switch segment arrangement makes it possible to combine the two required functional levels with four contact points each in a plane with six contact points.

In a particularly advantageous development of the invention, special pieces of special fireproof material may be attached, e.g. screwed, to the ends of the arc-shaped switch segment in a second plane - radially viewed. This also favors the volume increase of the special fireproof material required for an extended service life.

According to another feature of the invention, the fixed contacts attached to the insulating frame have upper and lower parallel contact fingers that can be pushed apart against the force of springs so that the switch segment can pass between them and make electrical contact.

A particular advantage of the invention is the reduction of parts; all fixed contacts are largely made up of identical components. Furthermore, due to the possible merging of the functional levels into a single plane in a particularly advantageous implementation of the invention, components are reduced in turn. Furthermore, the switch arrangement according to the invention requires only a significantly lower torque to operate, compared to the state of the art, since significantly fewer forces on the respective contact springs have to be overcome when the movable switch segment is running.

The invention is further explained below by means of illustrative drawings showing: Figure 1a switchgear in accordance with the inventionFigure 2a part of this switchgear in perspectiveFigure 3this part from above in schematic interfaceFigure 4a contact holder of the switchgear in accordance with the invention aloneFigure 5a fixed contact of the switchgear in accordance with the inventionFigure 6a part of such a contact in detailFigure 7a fixed contact which can be used in a particularly advantageous way in the switchgear in accordance with the inventionFigure 8a switchgear, i.e. the switchgear in accordance with the invention from one stationary operating position to another.

The switch arrangement is shown in Figure 1 as having a self-contained switch head 1 at the top, to which a circular upper cage ring 2 is attached. There is in turn an upper adapter 3 at the bottom end, with a lower cage ring 4 and, again, a lower adapter 5 attached to it. Between the upper adapter 3 and the lower adapter 5 there are contact rods 6 arranged vertically and parallel to each other.The number of layers - each with fixed contacts 7 - increases with increasing total current. The remaining free contacts 6 are so-called empty contacts, which are used to improve the rigidity of the overall arrangement. In Figure 1, the total of six fixed contacts of the first level with reference 7I, the second level with reference 7II, the third level with reference 7III.The connecting bridges 11, each designed twice per level, opposite each of two adjacent fixed contacts, provide a secure electrical contact between the two fixed contacts. The movable switchgear contacts 10 extend over a 120-degree arc, so that in each phase two brake and a free adjacent fixed contact 7 are simultaneously contacted in stationary condition and thus electrically connected to each other. The switchgear shaft 8 is actuated by an unrepresented maltose gear connected to an upper gear step 11 and driven by a drive shaft 12 which is known to be connected to a motor drive.

In Figure 2 a contact carrier 9 is shown in detail once again, attached to the switch shaft 8. In this representation it is even more clearly seen that on two horizontal opposite sides of the insulating contact carrier 9 the movable, arched switch contacts 10 are each attached. These switch contacts 10 are made of a solid electrically conductive material, preferably copper.

In Figure 3 below, this detail is shown again in schematic representation from above, and it is particularly clear that in the stationary state two bridges and a free-neighboring fixed contact 7 are electrically connected to each other.

Figure 4 shows in even more detail a contact carrier 9 alone, which carries the described massive, arched switch contacts 10. On the inside of the free ends of the switch contacts 10 is specially flame-resistant material 15 screwed. Furthermore, the free ends of the switch contacts 10 and the flame-resistant material 15 have a rounding 16 to allow better overlap on the respective fixed contacts to be switched, which will be explained in more detail below. The entire contact carrier 9 is attached by means of a flange connection 14 to the switch shaft 8 not shown here.

Figure 5 shows a complete fixed contact 7 of the switch arrangement according to the invention. This contact 7 has an upper contact holder 18 and a symmetrically formed lower contact holder 19 both pushed over the respective contact rod to which they are to be attached. Between this and the two contact holders 18, 19 a conductive contact 20 is fixed, which has a connecting hole 21 to fix the connection line not shown here. This conductive contact 20 is connected to the upper contact fingers 22 and the lower contact fingers 23 of the actual contact area.The suspension arrangement of the contact fingers 22, 23, which enclose the contact fingers 22, 23, on both sides, creates the required contact pressure and balances the slightly possible horizontal tolerances of the entire arrangement. At the front end of one of the two contact fingers 22 and 23, a fireproof material 30, 31 is anchored, which interacts with the fireproof material 15 at the switch 10 to exchange the upstream and downstream current.The position of the switch in the contact rods depends on whether the contact rods are arranged on the left or right side of the contact rod. There are also counter-bearings between the contact rods 22, 23 and 26. Above and below the contact rod, there is an upper shield 27 and a lower shield 28, each with corresponding openings in the middle, which allow the contact rod to be suspended.This part of a similar fixed contact with contact holders, shields and holes through which fastening bolts are pushed is already known from the applicant's DE 10 2004 041 317 B3.

Figure 6 shows a further detail of the fixed contact solely in accordance with the invention. It is shown here that the upper contact fingers 22 and the lower contact fingers 23 are arranged together with the contact springs 24, 25 in a separate, here omitted, contact housing 32. These contact fingers 22, 23 have on the opposite side contact brackets 33 and 34, which, after a particularly advantageous development of the invention, enclose the fixed contact 20 on both sides and thereby establish a direct electrical connection. The contact fingers 22 above and the discs 37 and the contact fingers 23 below and the discs 37 below (not shown here) help to avoid commutation between the contact fingers 22, 23 and contact 20 from the basic contact contacts on the previous switch and switch off the current.

Figure 7 shows a single fixed contact, whereby by simply clipping the contact brackets 33, 34 on the conductive contact 20, the fixed contact of the invention, as shown in Figure 5, can be modularly, i.e. according to the box system, produced in a simple manner.

The six fixed contacts in a phase are here designated by K1...K6. The left-hand representation shows the first stationary operating position; the direction of rotation at the beginning of the right-hand transformation is marked by an arrow. In the rotation, the adjacent rotors have each made a 60 degree rotation. Again in the rotation, the rotation angle is already slightly more than 60 degrees, which changes the current flowing through the switch; this is achieved by a double-slit operation.

Claims (9)

1. Switching arrangement with two operational settings for switching over a winding during transformer operation, wherein during the switching-over a transient current commutates from one current path to another current path, wherein at least one horizontal plane is provided for each phase to be switched, wherein in each horizontal plane fixed contacts are arranged around a centrally and vertically arranged rotatable switching shaft and on a common insulating-material frame and wherein selectable electrical connection with the fixed contacts in each plane can be made by at least one respective movable switching contact fastened on the switching shaft, characterised in that the movable switching contact (10) is constructed as a curved horizontally extending rail of electrically conductive material and that the fixed contacts (7) have upper and lower contact fingers (22, 23) which extend parallel to one another and which can be pressed apart against the force of upper and lower contact springs (24, 25) in such a manner that the movable switching contact (10) can run in therebetween and produce an electrical contact.
2. Switching arrangement according to claim 1, characterised in that the movable switching contact (10) consists of a solid rail of copper.
3. Switching arrangement according to claim 1 or 2, characterised in that the ends of the rail are narrowed.
4. Switching arrangement according to any one of claims 1 to 3, characterised in that the movable switching contact (10) is fastened to a contact carrier (9), which in turn is fixedly connected with the switching shaft (8), of insulating material.
5. Switching arrangement according any of claims 1 to 4, characterised in that material (15) resistant to erosion by burning is fastened to the ends of the movable switching contact (10).
6. Switching arrangement according to claim 5, characterised in that the material (15) resistant to erosion by burning is fastened in a second plane as seen radially.
7. Switching arrangement according to any one of claims 1 to 6, characterised in that the fixed contact (7) has an upper contact holder (18) and a lower contact holder (19) formed symmetrically thereto and that a conductive contact (20) is provided between the two contact holders (18, 19) and fixed by these.
8. Switching arrangement according to any one of claims 1 to 7, characterised in that at least one contact finger (22, 23) of material (30, 31) resistant to erosion by burning is arranged at the front end.
9. Switching arrangement according to any one of claims 1 to 8, characterised in that an upper screen (27) and a lower screen (28) are pushed onto the complete fixed contact (7) respectively at the top and bottom and that the contact holders (18, 19) as well as the screens (27, 28) are fixed to the insulating-material frame by means of bolts.