Compensation blocks for air chokes and transformers

Abstract

The invention relates to a compensating block for air choke coils and transformers, wherein the compensating block comprises a sandwich structure having an upper insulating material block, a lower insulating material block and an elastomer block located between the upper insulating material block and the lower insulating material block. The compensating block according to the invention can reduce gaps formed due to settling.

Description

[0001] Dry-insulated air choke coils are used, for example, in electrical systems for energy transmission and power supply systems of industrial plants in order to protect these systems or to increase the efficiency of these systems.

[0002] Since no insulating oil is used, the dry-insulated air choke is environmentally friendly and does not present an increased risk due to the risk of fire. In addition, the dry-insulated air choke is largely maintenance-free.

[0003] As a current limiting coil (or current limiting choke), the air choke is used to limit short-circuit currents in areas of a power grid which, due to its low grid impedance, has very high short-circuit currents in the event of a fault, for example in a transformer substation in the area of ​​multiply fed busbars.

[0004] The function of the series-connected current-limiting coil is to limit the short-circuit power by means of an impedance additionally introduced into the power grid, so that the power switch can safely interrupt the short-circuit current in the event of a fault.

[0005] Furthermore, the air choke coil is used as a smoothing choke device in a high-voltage direct current transmission system, for example.

[0006] Patent document WO 2009 / 126977 describes a typical air choke coil having concentric winding layers which are held at their upper and lower axial ends by a holding star element, which consists of a plurality of radially arranged arms in a star shape, so-called star blades.

[0007] Instead of a one-piece holding star, a plurality of individual star blades can also be used, which are only located in the area below and above the winding layers in order to save star blade material. The holding stars or star blades lying opposite one another are braced against one another by means of spacer strips or tension bands extending between the winding layers in order to hold the winding layers.

[0008] When winding the coil, the star blades and the spacer strips are used simultaneously as winding aids by first clamping the lower star blade on a rotating device and then placing the winding layers on the star blade, wherein a group of spacer strips is respectively placed between the winding layers.

[0009] It is known from patent document EP 2973 621B1 that in order to compensate for the different construction heights of individual winding layers due to different conductor cross-sections, a winding layer inclination compensation device is provided, in which compensation plates are inserted between axially opposite star-shaped blades and the winding layers located between the star-shaped blades, and the compensation plates support the winding layers on the star-shaped blades and center them in the axial direction.

[0010] After the production process of the air-type choke and during operation of the air-type choke, thermal and mechanical operating loads cause settling of the winding body and thus gaps to form, in particular at the winding ends.

[0011] These gaps must be compensated in a complex manner by suitable filling materials, which results in brief shutdowns of the system during continuous operation.

[0012] Therefore, the technical problem to be solved by the present invention is to improve the structure of the air choke coil so that the gap formed by the sedimentation can be reduced.

[0013] This is achieved according to the invention by a compensation block according to claim 1 .

[0014] Advantageous embodiments of the invention are disclosed in the dependent claims.

[0015] The present invention will be described in detail below with reference to the accompanying drawings.

[0016] In the accompanying drawings, for example:

[0017] Figure 1 A current-limiting coil is shown with concentrically arranged windings which are reinforced by means of glass-fiber-reinforced epoxy resin.

[0018] Figure 2 A detailed view of an upper winding head with a compensating block according to the invention is shown.

[0019] Figure 3 An arm of a star-shaped holding device with a compensation block according to the invention is shown, and

[0020] Figure 4 An arm of a star-shaped holding device with a compensating block according to the invention is shown during the assembly process.

[0021] according to Figure 1 The current-limiting coil has concentrically arranged windings reinforced with glass-fiber-reinforced epoxy resin, of which only the outer winding layers are visible.

[0022] The winding is held at the upper and lower ends by star-shaped holding devices, the arms of which extend radially from the coil axis beyond the radius of the outer winding.

[0023] According to the invention, a compensating block is inserted between the winding head of the air choke and the upper star arm.

[0024] Depend on Figure 2 , Figure 3 and Figure 4 It can be seen that the compensation block has a sandwich structure, which includes an upper insulating material block, a lower insulating material block, and an elastic body block located between the upper insulating material block and the lower insulating material block.

[0025] It is advantageous here if the upper star arm of the air choke and the compensation piece are connected in a form-fitting manner by means of a comb-like connection.

[0026] For this purpose, the spider has a rectangular recess, the width of which corresponds to the width of the compensating block and the height of which corresponds to a fraction of the height of the upper insulating material block of the compensating block.

[0027] The compensating piece has a groove as a counter-piece, which serves to accommodate a section of the spider arm above the rectangular recess.

[0028] The compensating piece is fixed in its position by means of this positive connection and is secured against slipping out.

[0029] The installation of the compensation block is achieved as follows:

[0030] - Pressing the compensating block with the aid of a clamping device;

[0031] - Insert the compensating block into the intended position between the winding head of the air choke and the upper star arm and release the clamping device.

[0032] The clamping device can be formed, for example, by a threaded pin which projects through the sandwich structure of the compensating piece and presses (or compresses) the compensating piece by screwing.

[0033] Alternatively, clamping devices based on clips, riveted connections or with snap locks are also conceivable. The compensating block according to the invention is preferably used for air choke coils, but it can also be used for windings of transformers.

[0034] Reference numerals list

[0035] 1 Outer winding layer

[0036] 2 Upper star-shaped holding arm

[0037] 3 Compensation block

[0038] 4 Upper insulating material block

[0039] 5 Elastic block

[0040] 6 Lower insulation block

[0041] 7 Clamping device

Claims

1. An air choke coil with a compensation block, wherein: The compensation block includes a sandwich structure, which has an upper insulating material block, a lower insulating material block and an elastomer block located between the upper insulating material block and the lower insulating material block, and is characterized in that the compensation block is arranged between the winding end of the air choke coil and the upper star arm, wherein the upper star arm of the air choke coil and the compensation block are connected in a shape-fitting manner by means of a comb-shaped connecting structure, wherein the star arm has a rectangular recess, the width of the recess corresponds to the width of the compensation block and the height of the recess corresponds to a part of the height of the upper insulating material block of the compensation block, and wherein the compensation block has a groove as a mating piece, which is used to accommodate the section of the star arm above the rectangular recess.

2. A compensation block for an air choke coil, the compensation block comprising a sandwich structure, the sandwich structure having an upper insulating material block, a lower insulating material block and an elastic body block located between the upper insulating material block and the lower insulating material block, characterized in that: The compensation block has a groove, wherein the compensation block can be connected to the upper star arm of the air choke coil in a form-fitting manner by means of a comb-like connecting structure, wherein the upper star arm has a rectangular recess, the width of which corresponds to the width of the compensation block and the height of which corresponds to a part of the height of the upper insulating material block of the compensation block, so that the compensation block can be arranged between the winding end of the air choke coil and the upper star arm, and wherein the groove is designed to accommodate a section of the star arm above the rectangular recess.

3. A method for installing a compensation block in an air choke coil according to claim 1, the method comprising the following method steps: - Press the compensating block with the aid of a clamping device, - insert the compensating block into the desired position between the winding head of the air choke coil and the upper star arm, - Release the clamping device.

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