Iron core structure of current transformer

Abstract

The utility model discloses an iron core structure of a current transformer, which comprises a protective shell and a core body, the protective shell comprises a cavity and a cover body, the cover body covers the upper end of the cavity to form a ring body structure with a ring-shaped cavity, and the outer diameter of the protective shell is equal to the outer diameter of the iron core required by design. A baffle is arranged in the protective shell to divide the annular cavity into two concentric annular cavities, namely a first cavity and a second cavity, the second cavity is located on the outer ring of the first cavity, a core body is installed in the first cavity and is made of an alloy material, and the size parameter of the core body is calculated according to the instrument security coefficient required by design. By adopting the special protective shell structure, not only can the security coefficient of an instrument be met, but also the requirement of consistency of the appearance size of a product can be met, and other accuracy levels (measurement levels) can be achieved, so that the cost and the product weight can be effectively reduced through the alloy with the structure under the conditions that the error score is ensured and the alloy is unsaturated.

Description

Technical Field

[0001] The utility model relates to the technical field of transformer cores, in particular to an iron core structure of an oil-immersed current transformer. Background Art

[0002] Oil-immersed current transformers provide electrical measurement and protection for 10-1000kV transformers. They feature a wrap-around structure and are placed inside the transformer's riser. Because they lack inserts for fixation, consistency in inner and outer diameters is essential. This allows customers to secure the transformer with epoxy panels around the perimeter.

[0003] When negotiating parameters, most customers will ask for an instrument safety factor with the accuracy level. The instrument safety factor limit means that the instruments and meters in the secondary circuit of the current transformer are not impacted by large currents. It is hoped that the secondary current of the current transformer used for measurement will no longer increase strictly in proportion to the overcurrent condition.

[0004] We use the measurement level error calculation formula:

[0005]

[0006] Where K 2z ——Considering the coefficient of winding internal impedance, usually K 2z =1.1~1.5;

[0007] A c ——Core cross section, cm 2 ;

[0008] I 2n ——Rated secondary current, A;

[0009] Z 2n ——Rated secondary load, Ω;

[0010] f——rated frequency, Hz;

[0011] N 2n ——Rated secondary turns;

[0012] B n ——Primary rated magnetic density, T.

[0013] To ensure the safety factor of the instrument, it is necessary to ensure that FS≤5, 100% point density is greater than 3000, FS≤10, 100% point density is greater than 1500. It can be seen from the formula that when the impedance, rated secondary current, rated secondary load, rated frequency, and rated secondary turns remain unchanged, in order to increase the density, the core cross-section must be reduced. Customers will specify the inner and outer diameters of the product at the initial stage of selection. Then, reducing the cross-section of the core will inevitably change the inner and outer diameters of the product, which violates the design requirement of consistency of the inner and outer diameters of the product. Therefore, it is necessary to design a new core structure to meet the above requirements. Summary of the Invention

[0014] Aiming at improving at least one defect of the prior art, the utility model provides an iron core structure of a current transformer, which solves the problem that the technical indicators and appearance dimensions of the iron core cannot meet the design requirements at the same time.

[0015] The technical solution adopted by the present invention is an iron core structure of a current transformer, comprising a protective shell and a core body, the protective shell comprising a cavity and a cover body, the cover body covering the upper end of the cavity to form a toroidal structure with a circular cavity, the outer diameter of the protective shell is equal to the outer diameter of the iron core required by the design, a baffle is provided in the protective shell to separate the circular cavity into two concentric annular cavities, namely a first cavity and a second cavity, the second cavity is located on the outer ring of the first cavity, the core body is installed in the first cavity, the core body is made of alloy material, and the size parameters of the core body are calculated according to the instrument safety factor required by the design.

[0016] Preferably, the cavity and cover of the protective shell are both integrally formed structures, and the cavity and cover are fixedly connected after the core is installed.

[0017] Preferably, the cross-sectional area of ​​the first cavity is adapted to the cross-sectional area of ​​the core, so that the core can be fixed exactly in the first cavity.

[0018] Preferably, the lower side of the baffle is fixed to the inner bottom surface of the cavity, and the upper side of the baffle is pressed against the lower surface of the cover.

[0019] The beneficial effects of the present invention are as follows: the present invention adopts a special shell structure that not only meets the instrument safety factor, but also meets the product's dimensional consistency requirements. In addition, other accuracy levels (measurement levels) can effectively reduce costs and product weight through the use of this structural alloy while ensuring error scores and alloy unsaturation. At the same time, this solution is also widely used in other accuracy levels (measurement levels) without instrument safety factors. While ensuring error scores and alloy unsaturation, this solution can be adopted. The purpose is not only to meet the parameters, but also to effectively reduce product costs and product weight, saving production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the cross-section structure of the core structure.

[0021] Figure 2 Schematic diagram of the cavity structure of the shell.

[0022] Figure 3 Schematic diagram of the cavity and cover structure of the protective shell.

[0023] Markings in the figure: 1-protective shell, 2-core body, 3-first cavity, 4-second cavity, 101-cavity, 102-cover body, 103-baffle. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0025] The principle of the utility model is to improve the density by reducing the effective cross-sectional area of ​​the iron core to meet the safety factor of the instrument, and to meet the design appearance size requirements of the product by adding a cavity structure to the outer ring of the shell.

[0026] like Figures 1 to 3 As shown, a core structure for a current transformer comprises a protective shell 1 and a core 2. The protective shell 1 includes a cavity 101 and a cover 102. The cover 102 covers the upper end of the cavity 101, forming a torus structure with a circular cavity. The cavity 101 and cover 102 of the protective shell 1 are integrally formed and are fixedly connected after the core 2 is installed. The outer diameter of the protective shell 1 is equal to the required outer diameter of the core. A baffle 103 is provided within the protective shell 1, dividing the circular cavity into two concentric annular cavities, namely a first cavity 3 and a second cavity 4. The second cavity 4 is located outside the first cavity 3. The core 2 is installed within the first cavity 3. The core 2 is made of an alloy, and its dimensional parameters are calculated based on the design safety factor of the instrument. The cross-sectional area of ​​the first cavity 3 matches that of the core 2, allowing the core 2 to be securely fixed within the first cavity 3. The lower side of the baffle 103 is fixed to the inner bottom surface of the cavity 101 , and the upper side of the baffle 103 is pressed against the lower surface of the cover 102 to separate the first cavity 3 from the second cavity 4 .

[0027] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements are intended to fall within the scope of the present invention. The scope of protection claimed in this invention is defined by the appended claims and their equivalents.

Claims

1. A core structure of a current transformer, characterized in that: It includes a protective shell and a core body. The protective shell includes a cavity and a cover body. The cover body covers the upper end of the cavity to form a torus structure with a circular cavity. The outer diameter of the protective shell is equal to the outer diameter of the iron core required by the design. A baffle is provided in the protective shell to separate the circular cavity into two concentric annular cavities, namely the first cavity and the second cavity. The second cavity is located on the outer ring of the first cavity. The core body is installed in the first cavity. The core body is made of alloy material. The size parameters of the core body are calculated according to the instrument safety factor required by the design.

2. The iron core structure of a current transformer according to claim 1, characterized in that: The cavity and cover of the protective shell are both integrally formed structures, and the cavity and cover are fixedly connected after the core is installed.

3. The iron core structure of a current transformer according to claim 1, characterized in that: The cross-sectional area of ​​the first cavity is adapted to the cross-sectional area of ​​the core.

4. The iron core structure of a current transformer according to claim 1, characterized in that: The lower side of the baffle is fixed to the inner bottom surface of the cavity, and the upper side of the baffle is pressed against the lower surface of the cover.

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