Combined current transformer
By pouring the three-phase current transformers together and wrapping them with high insulating material, the secondary load capacity and core saturation problems of the current transformers in the ring grid cabinet are solved, and the high load capacity and accuracy level limits are improved, reducing costs and volume.
Patent Information
- Application Number
- CN202421857059.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-02
- Publication Date
- 2025-07-04
- Estimated Expiration
- 2034-08-02
AI Technical Summary
The existing current transformers are limited by structural space in the ring grid cabinet, resulting in small secondary load capacity, serious core saturation, inability to operate accurately, and the high-voltage cables are not penetrated multiple times, affecting the effectiveness of the protection device.
The three-phase current transformers are poured together at one time, and as a multi-functional insulator in the ring cabinet, it realizes the winding of the multi-turn and enlarges the iron core cross-section. It uses high-insulating materials and the inner and outer insulators to wrap the high-voltage conductors, achieving multiple bypassing the iron core, enhancing insulation and safety.
The secondary load capacity and accurate level limit coefficient of the current transformer are improved, the volume is reduced, the insulation safety is enhanced, and the cost is reduced.
Smart Images
Figure CN223065995U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a combined current transformer, in particular to a high-voltage current transformer in which a three-phase current transformer is cast in an insulator and a cable connection cone head and an explosion-proof thin-wall area are formed at one time. Background Art
[0002] At present, the known current transformer structural features are as follows:
[0003] The existing current transformer used in the ring network cabinet can only be a through-type structure due to structural space limitations. The high-voltage cable passes through the current transformer once and cannot pass through the core multiple times (because the high-voltage cable is relatively hard). When the primary current is very small, the excitation current is also very small, resulting in a small secondary load capacity of the current transformer, which often cannot meet the needs, causing the protection device to fail to operate accurately.
[0004] The existing current transformers used in ring main units are limited by structural space, and the cross-section of the core cannot be increased. When a short circuit occurs, a very large short-circuit current will pass through, causing the core to saturate. Especially when the current transformation ratio is very small (which is most common in ring main units), the saturation is more serious, causing the secondary output current to not only have a severely distorted waveform, but also a sharp decrease in the effective value, which may cause the protection device to fail to operate. Utility Model Content
[0005] For the above defects and problems existing in the prior art, the utility model provides a solution, which casts the three-phase current transformer together at one time, and at the same time serves as a multifunctional insulating part in the ring network cabinet, replaces a sealing surface of the sealing compartment of the ring network cabinet, replaces the wall bushing, the phase-changing conductive part, etc., and realizes the purpose of winding the primary winding multiple turns (multiple turns) and increasing the cross section of the iron core. It has the characteristics of strong secondary load capacity, high accuracy limit coefficient, small space occupation, reliable insulation, etc.
[0006] In order to achieve the above purpose, the utility model provides the following technical solutions:
[0007] A combined current transformer comprises an outer insulator (3), an inner insulator (12), a current transformer primary winding (10), a current transformer iron core (11), a zero-sequence current transformer (17), a thin-walled area (7), a shielding net (18), etc.
[0008] Since all three-phase current transformers are pre-buried in the inner insulator (12), and since the material of the inner insulator (12) has high insulation performance, the safety distance between each high-voltage live body and between the ground can be made very small, the primary winding (10) of the current transformer can be easily made into a multiple-turn mode by using copper strip winding, and the cross-sectional area of the current transformer core (11) can also be increased as required. Therefore, the scheme can achieve the purpose of increasing the secondary load capacity and improving the accuracy level limit coefficient.
[0009] When the outer insulator (3) is cast, a cable connection cone head (6) and four thin-walled regions (7) are integrally formed at one time, which are respectively used for connecting cables and relieving pressure in the sealed chamber of the ring main unit.
[0010] Compared with the prior art, the beneficial effects of the present utility model are as follows:
[0011] The present utility model improves the secondary load capacity of the current transformer, and different load levels can be selected according to needs, without any restrictions.
[0012] The present utility model improves the accurate limit factor of the current transformer, and different levels can be selected according to needs, without being restricted by space.
[0013] The present utility model is provided with a cable connection cone head (6) and a primary grounding connection terminal (9), and realizes the conversion of the A, B, and C phase circuits from far, middle, and near arrangements to left, middle, and right arrangements, greatly reducing the volume and improving the insulation safety.
[0014] In summary, the present utility model has the characteristics of simple structure, small volume, low cost, and high parameter performance. Brief Description of the Drawings
[0015] Figure 1 It is the front view of the combined current transformer;
[0016] Figure 2 It is the left view of the combined current transformer;
[0017] Figure 3 It is the top view of the combined current transformer;
[0018] Figure 4 It is the bottom view of the combined current transformer;
[0019] Figure 5 It is the sectional view taken along the A-A direction of the combined current transformer Figure 2 ;
[0020] Figure 6 It is the axonometric view of the combined current transformer;
[0021] Figure 7 It is the axonometric view of the combined current transformer after removing the outer insulator (3) and the inner insulator (12).
[0022] In the figure: 1 - Inlet terminal umbrella skirt; 2 - Mounting flange; 3 - Outer insulator; 4 - Grounding terminal umbrella skirt; 5 - Outlet terminal; 6 - Cable connection cone head; 7 - Thin - walled area; 8 - Inlet terminal; 9 - Primary grounding connection terminal; 10 - Primary winding of current transformer; 11 - Core of current transformer; 12 - Inner insulator; 13 - Secondary terminal; 14 - Secondary terminal protection cover; 15 - Secondary terminal cavity; 16 - Primary conductor; 17 - Zero - sequence current transformer; 18 - Shielding net. Detailed implementation mode
[0023] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.
[0024] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.
[0025] According to Figures 1 to 7 As shown, the present utility model provides a combined current transformer, including: an outer insulator (3); an outlet terminal (5); an inlet terminal (8); a primary grounding connection terminal (9); a primary winding of the current transformer (10); a core of the current transformer (11); an inner insulator (12); a primary conductor (16); a zero - sequence current transformer (17); a shielding net (18).
[0026] It further includes: a cable connection cone head (6) integrally cast with the outer insulator (3) once, saving a separate wall - piercing bushing.
[0027] It further includes: four thin - walled areas (7) integrally cast with the outer insulator once, which can effectively direct and release the pressure air generated due to short - circuit faults in the sealed compartment of the ring - main unit, avoiding harm to people.
[0028] For the described combined current transformer, first, the three - phase current transformers (including the primary winding of the current transformer (10), the core of the current transformer (11) and accessories) are cast into one body with the inner insulator (12). After passing the inspection, it is then cast into the outer insulator (3) to form a combined current transformer.
[0029] When the combined current transformer is cast, an incoming line terminal (8), a primary grounding connection terminal (9), a secondary terminal (13), an outgoing line terminal (5), a zero-sequence current transformer (17), a shielding net (18), a primary conductor (16), etc. are also embedded. Current passes through the incoming line terminal (8) on the primary side, through the conductor to the primary winding (10) of the current transformer, bypasses the iron core (11) of the current transformer multiple times, and then is led to the primary grounding connection terminal (9) through the conductor. At the same time, it is also led to the outgoing line terminal (5) through the conductor. Since the three-phase circuit needs to change the arrangement direction, it will occupy a large space. However, due to the use of epoxy resin solid insulation with high insulation strength, the occupied space is reduced.
[0030] Since all high-voltage conductors are embedded in the inner insulator (12) or the outer insulator (3) during operation and are no longer exposed to the air, the safety during operation is improved, the volume is reduced, and the cost is lowered.
[0031] The specific functions and roles of the components of the present utility model are as follows:
[0032] (1) Incoming line terminal skirt 1 - used to increase the creepage distance;
[0033] (2) Mounting flange 2 - used for mounting and fixing;
[0034] (3) Outer insulator 3 - used for insulation molding;
[0035] (4) Grounding terminal skirt 4 - used to increase the creepage distance;
[0036] (5) Outgoing line terminal 5 - used for primary lead-out;
[0037] (6) Cable connection cone head 6 - used for connecting the cable;
[0038] (7) Thin-walled area 7 - used to relieve pressure in the sealed compartment of the ring main unit;
[0039] (8) Incoming line terminal 8 - used for primary introduction;
[0040] (9) Primary grounding connection terminal 9 - used for connecting the grounding switch;
[0041] (10) Primary winding 10 of the current transformer - used for electromagnetic induction of secondary current;
[0042] (11) Iron core 11 of the current transformer - used for electromagnetic induction;
[0043] (12) Inner insulator 12 - used for initially casting three current transformers together for shaping.
[0044] (13) Secondary terminal 13 - used for leading out secondary current;
[0045] (14) Secondary terminal protection cover 14 - used for protecting the secondary terminal;
[0046] (15) Secondary terminal cavity 15 - provides space for installing secondary conductors;
[0047] (16) Primary conductor 16 - used for connecting the primary circuit to conduct electricity;
[0048] (17) Zero - sequence current transformer 17 - used for detecting zero - sequence current;
[0049] (18) Shielding mesh 18 - used for evenly distributing the electric field to reduce partial discharge;
[0050] The following further describes the present utility model in conjunction with Figures 1 to 7 and specific embodiments:
[0051] Structural key points of the technical solution of the present utility model:
[0052] ① Firstly, the inner insulator (12) is used to cast and form the primary windings (10) of the three - phase current transformer, the iron core (11) of the current transformer, the primary conductor (16), the secondary terminal (13), etc. After passing the inspection, secondary casting is carried out to avoid waste due to unqualified products.
[0053] ② After the inner insulator (12) is cast and qualified, the outer insulator (3) is cast. At the same time, the incoming - line end umbrella skirt (1), the mounting flange (2), the grounding - end umbrella skirt (4), the cable connection cone head (6), and the thin - wall area (7) are formed.
[0054] ③ This combined current transformer can be used as a sealing surface of the sealed compartment of the ring - main unit, and at the same time, it can also be used as a current transformer, a through - wall bushing, and a phase - changing insulating part (converting the arrangement of A, B, and C phases in the far, middle, and near positions into the left, middle, and right positions).
[0055] This ensures that all conductive parts with insufficient safety distances during operation are completely wrapped by the insulator of the combined current transformer, isolating the atmosphere and ensuring safety during operation.
[0056] ④ When the inner insulator (12) is cast, the incoming - line end (8), the primary grounding connection terminal (9), the secondary terminal (13), and related connecting wires, etc. are also pre - embedded. The current passes through the incoming - line end (8), through the conductor to the primary winding (10) of the current transformer, bypasses the iron core (11) of the current transformer multiple times, and then passes through the conductor to the primary grounding connection terminal (9), and at the same time, passes through the conductor to the outgoing - line end (5).
[0057] Since the primary circuit can pass through the iron core (11) of the current transformer multiple times, a sufficient large exciting current can be generated even at a small rated current, increasing the load capacity on the secondary side and meeting various requirements. At the same time, the cross - sectional area of the iron core (11) of the current transformer can be effectively increased, improving the accurate - limit factor.
[0058] ⑤ When the outer insulator (3) is cast, four thin-wall regions (7) are formed in one piece, which can effectively direct and release the compressed air generated due to short-circuit faults in the sealed compartment of the ring main unit, avoiding harm to people.
[0059] For those skilled in the art, it is obvious that the present utility model is not limited to the details of the above-described exemplary embodiments, and the present utility model can be implemented in other specific forms without departing from the spirit or basic characteristics of the present utility model. Therefore, from any point of view, the above embodiments should be regarded as exemplary and non-restrictive. The scope of the present utility model is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present utility model. Any reference signs in the claims should not be construed as limiting the claimed invention.
[0060] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment contains only one independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A combined current transformer, characterized in that, It includes an inner insulator (12) in which three primary windings (10) of current transformers and three iron cores (11) of current transformers are cast. After the inner insulator (12) is formed by casting, it is cast again in an outer insulator (3).
2. The combined current transformer according to claim 1, wherein: When the outer insulator (3) is cast, a cable connection cone head (6) is formed simultaneously.
3. The combined current transformer according to claim 1, wherein: When the outer insulator (3) is cast, four thin-wall regions (7) are formed simultaneously.
4. A combined current transformer according to claim 1, characterized in that: When the outer insulator (3) is cast, a zero-sequence current transformer (17) is embedded simultaneously.
5. A combined current transformer according to claim 1, characterized in that: When the inner insulator (12) is cast, three-phase incoming line terminals (8), a primary grounding connection terminal (9), and secondary terminals (13) are also embedded.