CN114242381A

CN114242381A - Dry electromagnetic current mutual inductor

Info

Publication number: CN114242381A
Application number: CN202210054775.1A
Authority: CN
Inventors: 李涛昌; 王仁焘; 宋仁丰; 陈连友; 高琦; 向川; 刘丽娟; 娄云; 王鑫; 初立成; 王世阳; 李建龙; 周顺开; 于德强; 郐小娟; 朱松
Original assignee: Dalian North Instrument Transformer Group Co Ltd
Current assignee: Dalian North Instrument Transformer Group Co Ltd
Priority date: 2022-01-18
Filing date: 2022-01-18
Publication date: 2022-03-25

Abstract

The invention discloses a dry-type electromagnetic current transformer, which comprises an insulator and a coil body sealed in the insulator, wherein a P1 primary wiring terminal connected with the coil body is arranged at the top of the insulator, a P2 primary wiring terminal connected with the coil body is arranged at the lower part of the insulator, a secondary wiring terminal connected with the coil body is arranged at the bottom of the insulator, the secondary wiring terminal is positioned between the P2 primary wiring terminals, and the insulator is cast into an integrated structure by epoxy resin. The invention is formed by vacuum casting of epoxy resin, has small volume, large creepage distance, high dynamic and thermal stability current, high metering precision, moisture resistance, condensation resistance and electricity larceny prevention, and can be widely applied to the modification of the interior of a switch cabinet air chamber of a power system and a newly designed switch cabinet.

Description

Dry electromagnetic current mutual inductor

Technical Field

The invention relates to the technical field of high-voltage measurement of an electric power system, in particular to a dry-type electromagnetic current transformer which is suitable for a 35kV gas insulation cabinet.

Background

The current transformer is a device for measuring current, electric energy and relay protection in an electric power system or an electric control system, and in recent years, metal enclosed switchgear (C-GIS gas-filled cabinet for short) taking SF6 as an insulating medium is generally popularized and applied due to the advancement of small volume, high operation safety and suitability for various environments such as high altitude, high humidity and the like; the matched current transformer is positioned outside the high-voltage air chamber, a bus-through structure is adopted, and the matched primary high-voltage insulated cable is used as a primary winding, because of structural limitation, the current transformer can only be used in a large transformation ratio range, and the accuracy and the precision of a small current transformation ratio are difficult to guarantee; therefore, the application range of the similar switch cabinet equipment is limited, and the whole equipment has the problems of slightly large volume, more parts, low metering protection precision and the like, so that a current transformer which can be directly installed in a gas chamber of a gas insulation switch cabinet is particularly needed in switch cabinet manufacturers and markets.

Disclosure of Invention

The invention aims to provide a dry-type electromagnetic current transformer, which aims to solve the problems of low precision, low load, low partial discharge qualification rate, short service life of a product and the like existing outside an air chamber of the conventional 35kV gas insulation cabinet.

In order to achieve the purpose, the application provides a dry-type electromagnetic current transformer, which comprises an insulator and a coil body sealed in the insulator, wherein a P1 primary connecting terminal connected with the coil body is arranged at the top of the insulator, a P2 primary connecting terminal connected with the coil body is arranged at the lower part of the insulator, a secondary connecting terminal connected with the coil body is arranged at the bottom of the insulator, the secondary connecting terminal is positioned between the P2 primary connecting terminals, and the insulator is of an integrated structure formed by pouring epoxy resin.

Furthermore, the P1 primary connecting terminal is a square plane primary connecting terminal, the P2 primary connecting terminal is a groove type primary connecting terminal, and the two P2 primary connecting terminals are arranged along the horizontal direction.

Further, the coil body comprises an iron core, a primary winding and a secondary winding, wherein the secondary winding is wound on the iron core, the primary winding penetrates through the secondary winding, two ends of the primary winding are exposed outside, and the primary winding is connected with a P1 primary wiring terminal and a P2 primary wiring terminal respectively.

Furthermore, a low-voltage shielding net a and a low-voltage shielding net b are arranged in the insulator, the low-voltage shielding net a is close to a P1 end connecting plate, and the P1 end connecting plate is used for connecting a P1 primary connecting terminal with a primary winding; the low-voltage shielding net b is close to a P2 end connecting plate, and the P2 end connecting plate is used for connecting a P2 primary connecting terminal with a primary winding.

Furthermore, an aluminum powder layer is sprayed on the outer surface of the insulator after sand blasting to form an integral low-potential aluminum powder layer, the aluminum powder layer is tightly connected with an exposed metal sheet a and an exposed metal sheet b, the exposed metal sheet a is connected with a low-voltage shielding net a, and the exposed metal sheet b is connected with the low-voltage shielding net b.

Furthermore, the secondary connecting terminal protrudes out of the plane of the insulator at the end P2.

Furthermore, a plurality of installation inserts are arranged on the periphery of each P2 primary connecting terminal, the installation inserts are connected into a whole by a grounding wire, and a grounding connecting sheet is welded on one installation insert.

Furthermore, a sealing groove is formed around each P2 primary connecting terminal.

As a further step, the insulator has a square configuration.

As a further step, the low-voltage shielding net a is a plate-shaped structure, and the low-voltage shielding net b is a U-shaped structure.

The technical scheme adopted by the invention has the advantages that:

1. small size and large creepage distance: the dry-type electromagnetic current transformer is formed by vacuum casting of epoxy resin and is of an integral structure with the surface sprayed with aluminum powder, the iron core is sealed inside the insulator, the product has small volume, light weight, good partial discharge effect and long service life, and can be flexibly installed inside a 35kV gas insulation cabinet air chamber to be used for current and electric energy metering and relay protection.

2. The dynamic and thermal stability current is high, and the metering accuracy is high: the primary dynamic thermal stability current of the invention is high, and can effectively avoid the over-high temperature rise and insulation damage of the mutual inductor caused by system short circuit and over-current; the metering coil can be made into a complex transformation ratio form, the metering precision can reach 0.2S level, and the metering accuracy of the product under the conditions of wide load and large load change is effectively ensured.

3. Full-sealing, dampproof, prevent condensation: the invention is integrally formed by vacuum casting of epoxy resin, all parts are sealed in the insulating material, the product is ensured to have the functions of moisture prevention and condensation prevention, and the product cannot have the performance degradation phenomenon caused by the humidity and condensation of the operating environment.

4. The air chamber internally mounted leakproofness is good: the periphery of the groove type primary connecting terminal is provided with the sealing groove, when the groove type primary connecting terminal is installed in a gas insulation cabinet, a proper sealing strip is arranged in the sealing groove, and the insulator is ensured to be partially sealed in the gas insulation cabinet through fastening of the fastening bolt.

Drawings

FIG. 1 is a schematic diagram of an external structure of a dry-type electromagnetic current transformer;

FIG. 2 is a schematic diagram of an internal structure of a dry-type electromagnetic current transformer;

the sequence numbers in the figures illustrate: 1 is an insulator; 2 is a P1 primary connecting terminal; 3 is a P2 primary connecting terminal; 4 is an aluminum powder layer; 5, installing an insert; 6 is a sealing groove; 7 is a secondary wiring terminal; 8 is a grounding connecting sheet; 9 is a low-voltage shielding net a; 10 is a low-voltage shielding net b; 11 is an exposed metal sheet a; 12 is an exposed metal sheet b; 13 is a bracket; 14 is a secondary winding; 15 is an iron core; and 16 is a primary winding.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the application, i.e., the embodiments described are only a subset of, and not all embodiments of the application. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present application without making any creative effort, shall fall within the protection scope of the present application.

Example 1

As shown in fig. 1-2, a dry-type electromagnetic current transformer includes an insulator 1 and a coil body sealed in the insulator 1, a P1 primary connection terminal 2 connected with the coil body is arranged on the top of the insulator 1, a P2 primary connection terminal 3 connected with the coil body is arranged on the lower part of the insulator, a secondary connection terminal 7 connected with the coil body is arranged on the bottom of the insulator, the secondary connection terminal 7 is located between the P2 primary connection terminals 3, the insulator 1 is cast into an integral structure by epoxy resin, and an aluminum powder layer 4 is sprayed on the outer surface of the insulator to play a role in shielding and insulating.

Insulator 1 is square structure, has guaranteed on the even basis of inside coil insulation and electric field distance, makes the product structure more reasonable and size compact. The P1 primary connecting terminal 2 on the top of the insulator 1 is a square plane primary connecting terminal, and the P2 primary connecting terminal 3 on the lower part is a groove type primary connecting terminal. P2 once binding post 3 is two, and sets up along the horizontal direction respectively to convenient and the installation interface connection in same position.

The low-voltage shielding net a9 and the low-voltage shielding net b10 are arranged in the insulator, the low-voltage shielding net a is close to a P1 end connecting plate, and the P1 end connecting plate is used for connecting a P1 primary connecting terminal and a primary winding; the low-voltage shielding net b is close to a P2 end connecting plate, and the P2 end connecting plate is used for connecting a P2 primary connecting terminal and a primary winding; the outer surface of the insulator 1 is sprayed with the sand, and then the aluminum powder is sprayed to form an integral low-potential aluminum powder layer 4, and the aluminum powder layer is tightly connected with the insulator 1, the exposed metal sheet a11 and the exposed metal sheet b, so that the partial discharge effect is optimal, and the service life of the product is long.

The secondary wiring terminal 7 protrudes out of the plane of the insulator 1 at the P2 end, a product is installed in the gas cabinet, and the secondary wiring terminal 7 is exposed, so that wiring is facilitated.

The coil body comprises an iron core 15, a primary winding 16 and a secondary winding 14, wherein the secondary winding 14 is wound on the iron core 15, the primary winding 16 penetrates through the secondary winding 14, two ends of the primary winding are exposed outside, and the primary winding is respectively connected with a P1 primary connecting terminal and a P2 primary connecting terminal.

The manufacturing method of the dry type electromagnetic current transformer comprises the following steps:

the secondary winding 14 is uniformly wound on the annular iron core 15, the primary winding is formed by welding two parts and is assisted by binding insulating materials, and after the secondary winding 14 is bound, buffered and bound, a coil body with a P1 primary wiring terminal 2, a P2 primary wiring terminal 3, a primary winding 16, a secondary winding 14 and a secondary wiring terminal 7 is formed; the secondary winding 14 is fixed on a mould through a bracket 13, the primary winding 16 is fixed on the mould by adopting a P1 primary wiring terminal 2 and a P2 primary wiring terminal 3, and the distance is adjusted and then the primary winding is formed by vacuum casting and curing by using epoxy resin, so that the structure is integrated.

The insulator 1 for encapsulating the primary winding 16 and the secondary winding 14 is in a cuboid type, a P1 primary wiring terminal 2 at the top of the insulator and two P2 primary wiring terminals 3 at the lower part of the insulator are arranged in a separated mode, and the use requirement of a gas cabinet is effectively met; on the basis of ensuring the insulation of the internal coil and the uniform distance of an electric field, the product has more reasonable structure and compact size; the aluminum powder layer 4 sprayed on the surface of the insulator 1 is connected with the low-voltage shielding net a9 and the low-voltage shielding net b10 to effectively shield high voltage, so that the surface of the insulator 1 is low voltage.

When the intelligent cabinet is used, the mutual inductor installation insert is fixed with the installation hole of the cabinet body through the connecting piece, and then the primary bus and the secondary cable are electrically and mechanically connected, so that installation is completed.

The dry-type electromagnetic current transformer provided by the invention is a new product designed completely according to national standards, adopts a coiled iron core, utilizes the electromagnetic conversion principle, enables the secondary current to accurately reflect the change condition of the primary current to be measured, and transmits the change condition to a secondary metering and controlling device; the product is directly installed in a 35kV solid cabinet air chamber and used for current and electric energy measurement and relay protection.

The invention is formed by vacuum casting of epoxy resin, has small volume, large creepage distance, high dynamic and thermal stability current, high metering precision, moisture resistance, condensation resistance and electricity larceny prevention, and can be widely applied to the modification of the interior of a switch cabinet air chamber of a power system and a newly designed switch cabinet.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims

1. A dry-type electromagnetic current transformer is characterized by comprising an insulator and a coil body sealed in the insulator, wherein a P1 primary wiring terminal connected with the coil body is arranged at the top of the insulator, a P2 primary wiring terminal connected with the coil body is arranged at the lower part of the insulator, a secondary wiring terminal connected with the coil body is arranged at the bottom of the insulator, the secondary wiring terminal is located between the P2 primary wiring terminals, and the insulator is of an integrated structure formed by pouring epoxy resin.

2. A dry type electromagnetic current transformer as claimed in claim 1, wherein said P1 primary terminals are square plane primary terminals, said P2 primary terminals are groove type primary terminals, and said P2 primary terminals are two terminals, both arranged in a horizontal direction.

3. A dry-type electromagnetic current transformer as claimed in claim 1 wherein said body comprises an iron core, a primary winding and a secondary winding, wherein said secondary winding is wound around said iron core, said primary winding is inserted through said secondary winding with both ends exposed, and connected to a P1 primary connection terminal and a P2 primary connection terminal respectively.

4. A dry type electromagnetic current transformer as claimed in claim 1, wherein said insulator has a low voltage shielding net a and a low voltage shielding net b inside, said low voltage shielding net a is close to a P1 end connection board, said P1 end connection board is used for connecting a P1 primary connection terminal with a primary winding; the low-voltage shielding net b is close to a P2 end connecting plate, and the P2 end connecting plate is used for connecting a P2 primary connecting terminal with a primary winding.

5. A dry-type electromagnetic current transformer as claimed in claim 1 wherein the outer surface of said insulator is sandblasted and then an aluminum powder layer is sprayed to form an integral low potential aluminum powder layer, said aluminum powder layer is tightly connected to an exposed metal sheet a and an exposed metal sheet b, said exposed metal sheet a is connected to a low voltage shielding mesh a, and said exposed metal sheet b is connected to b.

6. A dry-type electromagnetic current transformer as claimed in claim 1, wherein said secondary terminals project above the plane of the P2 terminal insulator.

7. A dry-type electromagnetic current transformer as claimed in claim 1, wherein each of said P2 primary terminals is provided with a plurality of mounting inserts around the periphery thereof, said plurality of mounting inserts are integrally connected by a ground wire, and a ground connection piece is soldered to one of said mounting inserts.

8. A dry-type electromagnetic current transformer as claimed in claim 1, wherein each of said P2 primary terminals is provided with a sealing groove around its periphery.

9. A dry-type electromagnetic current transformer as recited in claim 1, wherein said insulator is of a square configuration.

10. A dry-type electromagnetic current transformer as claimed in claim 4 wherein said low voltage shielding mesh a is a plate-like structure and said low voltage shielding mesh b is a U-shaped structure.