Current transformer

Abstract

The utility model discloses a current transformer. The current transformer comprises an expander, an oil conservator, an outer insulator and a main insulator, the expander is fixedly connected to the oil conservator, the outer insulator is fixedly connected to the oil conservator, the main insulator is arranged in the outer insulator, and the main insulator comprises a capacitive screen which extends in the axial direction of the current transformer and is provided with a first end on one side of the oil conservator and a second end opposite to the first end; comprising a plurality of cylindrical electrodes coaxially arranged in the axial direction, each electrode is provided with a main body made of carbon fibers, and a space filled with insulating oil is formed between the capacitive screen and the outer insulator; the main insulating ring part is arranged at the first end of the capacitive screen and is of an annular structure; and the end screen is arranged on the innermost side or the outermost side of the capacitive screen along the radial direction of the current transformer, and is connected with the end screen terminal through an end screen lead arranged at the second end of the capacitive screen. Reliable connection is realized through the end screen and the lead wire which are made of the carbon fiber material by adopting an omnibearing equipotential method.

Description

Technical Field

[0001] The utility model relates to the technical field of current transformers, in particular to a carbon fiber oil-immersed current transformer. Background Art

[0002] Current transformer is an instrument made according to the principle of electromagnetic induction. It is used in the process of power generation, transformation, transmission, distribution and consumption. It transforms the current and is used for electrical isolation. In the power system, current transformer is an important primary device for measuring line current, and oil-immersed current transformer has been widely used in power transmission systems at home and abroad.

[0003] The main insulator of the oil-immersed current transformer is composed of cable paper and aluminum foil screen, and is immersed in insulating oil. When the circuit breaker is actuated, the current transformer is easily subjected to high-frequency shocks. In the case of repeated high-frequency shocks, the main insulation and the copper braid lead of the current transformer are easily damaged, which has a great impact on the stability of the current system. Utility Model Content

[0004] In view of this, the utility model proposes a current transformer to solve part or all of the above problems.

[0005] According to an embodiment of the utility model, a current transformer is provided, comprising an expander, an oil conservator, an outer insulator, and a main insulator, wherein the expander is fixedly connected to the oil conservator, the outer insulator is fixedly connected to the oil conservator, and the main insulator is arranged inside the outer insulator, and is characterized in that the main insulator comprises: a capacitor screen, extending along the axial direction of the current transformer, having a first end on one side of the oil conservator and a second end opposite to the first end, wherein the capacitor screen comprises a plurality of cylindrical electrodes coaxially arranged along the axial direction of the current transformer, each of the electrodes having a main body made of carbon fiber, and having a space for filling insulating oil between the capacitor screen and the outer insulator; a main insulating ring portion, arranged at the first end of the capacitor screen, and having a ring structure; an end screen, arranged at the innermost or outermost side of the capacitor screen along the radial direction of the current transformer, and connected to the end screen terminal via an end screen lead arranged at the second end of the capacitor screen.

[0006] In the current transformer proposed by the utility model, each of the electrodes has a main body made of carbon fiber, thereby utilizing the characteristics of carbon fiber materials such as high temperature resistance, corrosion resistance, excellent conductivity, and high insulation strength to provide a current transformer with better performance. In addition, the impregnation performance of carbon fiber is better than that of aluminum foil, and no potential difference is generated inside the capacitor screen using carbon fiber, thereby ensuring stable performance. Moreover, the carbon fiber material is suitable for transformers of any voltage / current level, providing universal performance.

[0007] Preferably, the end screen has a body made of carbon fibres.

[0008] In the current transformer proposed in the utility model, the end screen has a main body made of carbon fiber. The carbon fiber material has high tensile strength, the end screen connection is more reliable, the product's ability to withstand high-frequency impact is guaranteed, and the reliability of the end screen connection is improved.

[0009] Preferably, the end screen lead has a body made of carbon fiber.

[0010] In the current transformer proposed in the utility model, the end screen lead has a main body made of carbon fiber. The carbon fiber material has high tensile strength, the end screen connection is more reliable, the product's ability to withstand high-frequency impact is guaranteed, and the reliability of the end screen connection is improved.

[0011] Preferably, the end screen terminal has a body made of carbon fiber.

[0012] In the current transformer proposed in the utility model, the end screen terminal has a main body made of carbon fiber. The carbon fiber material has high tensile strength, the end screen connection is more reliable, the product's ability to withstand high-frequency impact is guaranteed, and the reliability of the end screen connection is improved.

[0013] Preferably, the end of the current transformer opposite to the expander is connected to a base (220), the base supports the current transformer, and the end screen terminal is arranged in a secondary junction box (218), and the secondary junction box is arranged on the base.

[0014] Preferably, the secondary junction box and the base are fixedly connected to each other via a sealing ring and a fastener.

[0015] Preferably, the outer insulator is a combined outer insulator, which includes a first outer insulator unit and a second outer insulator unit, the first outer insulator unit is cylindrical, the outer surface of the second outer insulator unit has a wavy umbrella edge, the upper end of the first outer insulator unit is connected to the oil storage cabinet, the lower end of the first outer insulator unit is connected to the base, and the first outer insulator unit is sleeved on the outside of the second outer insulator unit.

[0016] Preferably, the first outer insulator unit and the second outer insulator unit are integrally formed.

[0017] Preferably, the current transformer is an oil-immersed current transformer.

[0018] It can be seen from the above scheme that in view of the characteristic that the current transformer operates under high-frequency impact conditions, the aluminum foil screen, the end screen lead wire and the end screen terminal are replaced by carbon fiber materials. Carbon fiber materials have the following excellent properties: high temperature resistance, friction resistance, transformer oil corrosion resistance, electrical conductivity, thermal conductivity, insulation strength and tensile strength, impregnation performance, and seamless connection with insulating paper. Therefore, the end screen and lead wire made of carbon fiber material are used to achieve reliable connection and complete shielding by adopting a full-range equipotential method. Thus, a new type of oil-immersed current sensor is provided, which can be applied to transformers of any voltage / current level. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so that those skilled in the art will be more aware of the above and other features and advantages of the present invention. In the accompanying drawings:

[0020] Figure 1 A schematic diagram of an oil-immersed current transformer according to the utility model is shown.

[0021] Reference Numbers

[0022] 20 Current transformer

[0023] 202 expander

[0024] 204 oil storage cabinet

[0025] 206 primary terminal

[0026] 208 Main Insulator

[0027] 210 external insulator

[0028] 210-1 first outer insulator unit

[0029] 210-2 Second outer insulator unit

[0030] 212 insulating oil

[0031] 208-2 Main insulation ring

[0032] 208-4 capacitive screen

[0033] 208-6 Last screen

[0034] 208-8 end screen lead

[0035] 216 end screen terminal

[0036] 218 secondary junction box

[0037] 220 base DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail in the following embodiments.

[0039] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present utility model will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0040] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0041] In the present invention, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity directions; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above-mentioned directional words are not used to limit the present invention.

[0042] The oil-immersed current transformer according to the prior art includes: an expander, an oil conservator, a primary terminal, a main insulator, an outer insulator, insulating oil, an end screen lead, an end screen terminal, and a secondary junction box. The expander can be fixedly connected to the oil conservator through a sealing ring and a fastener, and the outer insulator is fixedly connected between the oil conservator and the base.

[0043] The main insulator includes: main insulating ring, aluminum foil screen, end screen, and end screen lead. As mentioned before, when the main insulation of the oil-immersed current transformer is composed of cable paper and aluminum foil screen and the end screen lead is a copper wire braid, the oil-immersed current transformer is immersed in insulating oil. When the circuit breaker is operated, the current transformer is easily subjected to high-frequency shock. In the case of repeated high-frequency shock, the main insulator and the end screen copper braid lead of the current transformer are easily damaged, which has a great impact on the stability of the current system.

[0044] Next, refer to Figure 1 A schematic diagram of an oil-immersed current transformer according to the utility model is described in detail.

[0045] like Figure 1 As shown in Figure 1 As shown in (A) in FIG. 1 , the structure of the oil-immersed current transformer 20 according to the present invention is roughly similar to that of the oil-immersed current transformer according to the prior art. Figure 1In (A), the dotted line AA' shows the axis of the oil-immersed current transformer 20, and the right side of the dotted line AA' shows a partial cross-sectional view of the oil-immersed current transformer 20. For example, Figure 1 As shown in (A), the oil-immersed current transformer 20 according to the utility model includes: an expander 202, an oil storage cabinet 204, a primary terminal 206, a main insulator 208, an outer insulator 210, insulating oil 212, an end screen lead 208-8, an end screen terminal 216, a secondary junction box 218, and a base 220. The expander 202 can be fixedly connected to the oil storage cabinet 204 by a sealing ring and a fastener, and the outer insulator 210 is fixedly connected between the oil storage cabinet 204 and the base 220. For example, the secondary junction box 218 is arranged on the base 220, and the secondary junction box 218 and the base 220 are fixedly connected to each other by a sealing ring and a fastener. The end screen terminal 216 is arranged in the secondary junction box 218. For example, the secondary junction box 218 is fixed to the base by an adjustable hinge and a fixing nut. The outer insulator 210 can be a porcelain sleeve. In addition, the outer insulator 210 may be a combined outer insulator, which includes a first outer insulator unit 210-1 and a second outer insulator unit 210-2, wherein the first outer insulator unit 210-1 is cylindrical, and the outer surface of the second outer insulator unit 210-2 has a wavy umbrella edge, the upper end of the first outer insulator unit is connected to the oil storage cabinet, the lower end of the first outer insulator unit is connected to the base, the second outer insulator unit is connected to the first outer insulator unit, and the first outer insulator unit is sleeved outside the second outer insulator unit. The first outer insulator unit and the second outer insulator unit may be formed integrally.

[0046] like Figure 1 As shown in (B) of Figure 1The cross-sectional view taken along the dotted line A-A' in (A) shows in detail the specific structure of the main insulator 208. The main insulator 208 includes: a main insulating ring portion 208-2, a capacitor screen 208-4, an end screen 208-6, and an end screen lead 208-8. The capacitor screen 208-4 extends along the axial direction of the current transformer, and includes a plurality of coaxially arranged cylindrical electrodes, each electrode having a main body made of carbon fiber. There is a space for filling insulating oil between the capacitor screen and the outer insulator. The end screen 208-6 is arranged at the innermost or outermost side of the capacitor screen along the radial direction of the current transformer (i.e., perpendicular to the axis of the oil-immersed current transformer 20 shown by the dotted line A-A'), and the end screen is connected to the end screen terminal 216 arranged in the secondary junction box via the end screen lead 208-8. Since carbon fiber materials have the following excellent properties: high temperature resistance, friction resistance, transformer oil corrosion resistance, electrical conductivity, thermal conductivity, insulation strength and tensile strength, impregnation performance, and seamless connection with insulating paper, the capacitor screen 208-4, the end screen 208-6, the end screen lead 208-8, and the end screen terminal 216 are formed of carbon fiber materials to replace the aluminum foil screen, copper end screen lead wire, and copper end screen terminal in the current transformer in the prior art. Therefore, the end screen and lead made of carbon fiber material adopt a full-range equipotential method to achieve reliable connection and complete shielding. Thus, a new type of oil-immersed current sensor is provided, which can be applied to transformers of any voltage / current level.

[0047] It can be seen from the above scheme that a new type of oil-immersed current sensor is provided. The oil-immersed current sensor according to the utility model can achieve the following technical effects: 1. Excellent performance (for example, carbon fiber materials are resistant to high temperature and corrosion; excellent in conductivity and high in insulation strength); 2. The reliability of the end screen connection is improved (for example, the carbon fiber material has high tensile strength, the end screen connection is more reliable, and the product's ability to withstand high-frequency impact is guaranteed); 3. Excellent impregnation performance (for example, the carbon fiber impregnation performance is better than aluminum foil); 4. Stable performance (for example, no potential difference is generated inside the capacitor screen using carbon fiber); 5. Universal performance (for example, carbon fiber materials are suitable for transformers of any voltage / current level).

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A current transformer (20), comprising an expander (202), an oil conservator (204), an outer insulator (210), and a main insulator (208), wherein the expander is fixedly connected to the oil conservator, the outer insulator is fixedly connected to the oil conservator, and the main insulator is arranged inside the outer insulator, characterized in that: The main insulator comprises: a capacitor screen (208-4) extending along the axial direction of the current transformer, the capacitor screen having a first end on one side of the oil storage cabinet and a second end opposite to the first end, wherein the capacitor screen comprises a plurality of cylindrical electrodes coaxially arranged along the axial direction of the current transformer, each of the electrodes having a main body made of carbon fiber, and a space for filling insulating oil between the capacitor screen and the outer insulator; A main insulating ring portion (208-2) is arranged at the first end of the capacitive screen, and the main insulating ring portion has a ring structure; An end screen (208-6) is arranged at the innermost or outermost side of the capacitor screen along the radial direction of the current transformer, and the end screen is connected to an end screen terminal (216) via an end screen lead (208-8) arranged at the second end of the capacitor screen.

2. The current transformer according to claim 1, characterized in that: The end screen has a body made of carbon fiber.

3. The current transformer according to claim 1 or 2, characterized in that: The end screen lead has a body made of carbon fiber.

4. The current transformer according to claim 1 or 2, characterized in that: The end screen terminal has a main body made of carbon fiber.

5. The current transformer according to claim 1 or 2, characterized in that: The end of the current transformer opposite to the expander is connected to a base (220) that supports the current transformer, and the end panel terminal is arranged in a secondary junction box (218) that is arranged on the base.

6. The current transformer according to claim 5, characterized in that: The secondary junction box and the base are fixedly connected to each other via a sealing ring and a fastener.

7. The current transformer according to claim 5, characterized in that: The outer insulator is a combined outer insulator, comprising a first outer insulator unit (210-1) and a second outer insulator unit (210-2), the first outer insulator unit being cylindrical, the outer surface of the second outer insulator unit having a wavy umbrella edge, the upper end of the first outer insulator unit being connected to the oil storage cabinet, the lower end of the first outer insulator unit being connected to the base, and the first outer insulator unit being sleeved outside the second outer insulator unit.

8. The current transformer according to claim 7, characterized in that: The first outer insulator unit and the second outer insulator unit are integrally formed.

9. The current transformer according to claim 1, characterized in that: The current transformer is an oil-immersed current transformer.

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