HRP930794A2 - Combined electrical and voltage transformer for high voltage - Google Patents

Description

The field of technology

The subject of the invention is a combined current and voltage transformer for high voltages.

According to the fourth edition of the International Classification of Patents, the technical field from which the invention originated is designated by subgroup H01F-040/08 entitled: "Measuring transformers for single-phase alternating current combined voltage and current".

Technical problem

Combined current and voltage transformers are most often performed as separately isolated current or voltage transformers placed in one or two housings with a common supporting insulator.

This design of combined transformers represents a technical solution which, when applied to transformers for high voltages, results in a relatively expensive and inappropriate design due to the increase in dimensions and weight of the transformer.

The invention solves the technical problem of finding a new version of the combined current and voltage transformer for high voltages by placing the complete inductive voltage transformer in a supporting insulator.

State of the art

According to the current state of the art, inductive combined transformers are made so that the current transformer and the voltage transformer with a closed magnetic core are placed in one common or two separate metal housings. At the same time, in practice, all layout combinations are possible. The most common variants are that the current transformer of the inverse type is located in the head and the voltage transformer in the base, or that both transformers are located in the head of the combined transformer. In this last variant, two combinations are also possible, whereby the active part of the voltage transformer can be placed above or below the current transformer.

Utility model DE7234359 describes one known solution. The problem was solved by placing the round core of the voltage transformer, with the associated primary and secondary windings, under the inverse current transformer. The complete active part is cast in a compact body made of artificial resin and placed inside a supporting insulator. In the window of the horizontally laid core of the voltage transformer, a metal pipe passes through which the secondary leads of the voltage transformer are carried. This pipe in the middle of the window is connected to the metal pipe of the current transformer, where the secondary leads of the current and voltage transformer are intertwined and are led towards the base of the transformer through a common vertical metal pipe.

The main disadvantage of this solution is that the volume, mass and height of the transformer head are relatively large compared to the supporting insulator, and this ratio increases with the increase in the rated voltage of the transformer. Furthermore, due to the distribution of weight, the center of gravity of the transformer is high from the base of the transformer, so this design is statically unstable, especially in earthquake conditions.

As it is a design whose active part is filled with artificial resin, as the rated voltage of the transformer increases, the production technology becomes very complicated and expensive, so it is practically inapplicable at very high voltages.

The primary winding of the voltage transformer needs to be insulated for full voltage to the current transformer, which additionally increases the dimensions and weight of the combined transformer constructed in this way.

The metal pipe through which the secondary outputs of the voltage transformer are conducted must be insulated for full voltage, which requires even more space.

The essence of invention

The performance of combined current and voltage transformers shown in the state of the art is unsuitable for the production of combined transformers of high nominal voltages.

The essence of the invention is contained in the application of an inductive voltage transformer with an open core, which is placed in a supporting insulator and forms an integral part of the combined transformer. In this way, part of the insulation of the inverse current transformer, which isolates its supporting mechanical tube from high voltage, is used as insulation of the voltage transformer, and the hollow space inside that tube is used to house the core and secondary windings of the voltage transformer. With this solution, all the shortcomings associated with the solution with a compact active part located in the head of the combined transformer have been removed.

Image description

Figure 1 shows a longitudinal section of a combined current and voltage transformer for high voltages.

Description of the performance and application of the invention

The mentioned shortcomings are solved by the new concept of the combined current and voltage transformer for high voltages, where the current transformer is made as an inverse type transformer with cores and secondary charges placed in the head of the combined transformer. The voltage transformer is made with an open magnetic core, which with its secondary windings is placed vertically at the height of the combined transformer, inside the support tube, through which the secondary outputs of the current transformer also pass. The primary winding of the voltage transformer is made of several sections that are wound around the perimeter of the main insulation wound on a support tube located vertically inside the support insulator.

The particular advantage of the solution according to the invention, compared to known solutions, is that it takes up much less space. This is achieved by placing the open magnetic core and secondary windings of the voltage transformer inside the support tube that carries the active part of the current transformer. Furthermore, the primary winding of the voltage transformer arranged along the height of the supporting insulator on the one hand contributes to saving space and at the same time optimizes the potential distribution along the height of the transformer.

Also, the advantage of the solution according to the invention is mechanical stability due to the fact that by placing the core and primary winding of the voltage transformer vertically inside the support insulator, an even weight distribution is obtained inside the combined transformer.

The technology of manufacturing and assembling the combined transformer, according to the invention, is similar to the manufacturing and assembling of current transformers of the inverse type. This similarity enables relatively simple production of combined transformers for the highest nominal voltages.

The combined current and voltage transformer for high voltages shown in Figure 1 consists of a head 1, a supporting insulator 2 and a base 3.

In the head 1 are located the cores and secondary windings 4 of the current transformer, which are isolated from the potential of the head 1 by the corresponding part 5 of the main insulation. The primary winding 6 of the current transformer in this embodiment is shown as a rod winding with one turn. In practice, other variants with a larger number of turns and with double and quadruple switching on the primary side of the current transformer are feasible.

The secondary leads 7 of the current transformer are passed along or through the open magnetic core 9 of the voltage transformer to the secondary connection box 10 at the base 3 of the transformer.

The open magnetic core 9 of the voltage transformer is made as a stacked core with one or more sheet packages, and it is mechanically fixed in the base 3 of the transformer. The secondary windings 11 of the voltage transformer are wound along the open magnetic core 9, the leads of which end in the secondary connection box 10. The open magnetic core 9 with the secondary windings 11 of the voltage transformer is placed vertically inside the support tube 8. The support tube 8 is also the supporting mechanical support of the current transformer.

The overall main insulation of the combined current and voltage transformer forms one compact unit, consisting of part 5, insulation of the current transformer in the area of the transformer head, and part 12, insulation of the voltage transformer, which is also the insulation of the support pipe 8. Part 12, insulation of the voltage transformer , can be designed step by step so that the thickness of the insulation decreases from the top towards the grounded parts of the transformer.

Around the perimeter of the insulation of the voltage transformer 12, in the vertical axis of the transformer, the primary winding 13 of the voltage transformer is located. Depending on the rated voltage of the transformer, the primary winding 13 of the voltage transformer can be divided into several to dozens of sections. Each section of the primary winding 13 contains a certain number of turns which are wound in the form of a layered winding on section supports made of insulating material.

Claims (5)

1. Combined current and voltage transformer for high voltages, which consists of an inverse-type current transformer located in the transformer head and an inductive voltage transformer with a stacked magnetic core, indicated by the fact that the secondary leads (7) of the current transformer pass along or through the open magnetic core ( 9) of the voltage transformer, which with the associated secondary winding (11) of the voltage transformer is located in the vertical axis of the transformer inside the grounded support tube (8) and around which is the insulation of the voltage transformer (12), which with the insulation of the current transformer in the head area (5) forms one indivisible unit and that the sections of the primary winding (13) of the voltage transformer are located vertically inside the support insulator (2) around the insulation of the voltage transformer (12). 2. Combined current and voltage transformer for high voltages according to claim 1, characterized in that the primary winding (6) of the current transformer has one or more turns. 3. Combined current and voltage transformer for high voltages according to claim 1, characterized in that the current transformer has one or more cores (4). 4. Combined current and voltage transformer for high voltages according to patent claim 1, indicated by the fact that the current transformer is multiple switchable on the primary and/or secondary side. 5. Combined current and voltage transformer for high voltages according to claim 1, characterized in that the voltage transformer has one or more secondary windings (11).