Integrated sleeve type electronic current transformer
By using the fully sealed structure of the integrated bushing-type electronic current transformer, the problem of limited space inside the ring main unit is solved, and efficient integration of current measurement and capacitor status monitoring is achieved, reducing the transformation cost and maintaining high-precision signal output.
Patent Information
- Application Number
- CN202522517173.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-27
- Publication Date
- 2026-01-06
- Estimated Expiration
- 2035-11-27
AI Technical Summary
The limited space inside the ring main unit makes it impossible to accommodate traditional current transformers or large electronic current transformers, resulting in high renovation costs and complex construction.
Design an integrated bushing-type electronic current transformer. It adopts a fully sealed bushing structure and integrates current measurement and capacitance status monitoring functions. It utilizes epoxy resin to encapsulate the conductive rod, capacitance sensing network and coil body to achieve compact current signal output and insulation monitoring.
It achieves efficient integration within the ring main unit, reduces retrofit costs, maintains high-precision current signal output, and features resistance to moisture and dirt and maintenance-free operation throughout its lifespan. It is suitable for compact cabinet installation.
Smart Images
Figure CN223770939U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of current transformer technology in power equipment, specifically to an integrated bushing-type electronic current transformer. Background Technology
[0002] Ring main units are indispensable key power distribution equipment in modern urban power distribution networks, industrial parks, commercial centers, large buildings, infrastructure (such as airports, train stations, and hospitals), residential communities, and renewable energy power plants (such as wind farms and photovoltaic power stations) and their substations. They have advantages such as high reliability, compact structure, and high degree of modularity, and are widely used in power grids.
[0003] However, the internal space of ring main units is usually extremely limited, and they generally adopt a fully insulated and sealed structure. This characteristic makes it very difficult to directly install traditional current transformers (CTs) or large electronic current transformers (such as ECTs) inside the cabinet. With the deepening of the automation transformation of distribution networks, the number of secondary equipment that needs to be integrated into ring main units has increased significantly, and the demand for current signal acquisition, measurement, monitoring, and protection functions is becoming increasingly prominent.
[0004] The main problems with existing technologies are:
[0005] Limited installation space and structural conflicts: The small, fully insulated structure of the ring main unit cannot accommodate large traditional instrument transformers or combined electronic instrument transformers.
[0006] High retrofit costs: To meet automation requirements, a dedicated CT (Cellular Temperature Coefficient) is usually needed, which not only has high equipment costs but also occupies valuable cabinet space. Retrofitting existing ring main units is even more difficult, complex, and extremely costly. Utility Model Content
[0007] To address the aforementioned problems, the purpose of this utility model is to provide an integrated bushing-type electronic current transformer to solve the problems of traditional current transformers occupying a large space and being unable to fit into compact cabinets.
[0008] To achieve the above objectives, the present invention adopts the following technical solution:
[0009] This utility model provides an integrated bushing type electronic current transformer, including an insulating encapsulation structure and a conductive rod, a current measurement module and a capacitance monitoring module encapsulated within the insulating encapsulation structure. The insulating encapsulation structure is an epoxy resin shell cast into a fully sealed bushing shape. A terminal block is provided on the side of the epoxy resin shell. The conductive rod axially penetrates the insulating encapsulation structure and has both ends exposed.
[0010] The capacitance monitoring module includes a capacitance terminal block and a cylindrical capacitance sensing mesh. The capacitance sensing mesh is fitted on the outside of the conductive rod. The capacitance sensing mesh and the conductive rod together form a monitoring capacitor for outputting a capacitance signal that reflects the dielectric state of the epoxy resin. The capacitance terminal block is located on the terminal block and is connected to the capacitance sensing mesh.
[0011] The current measurement module includes a coil body and a current-shielded twisted pair cable. The coil body is mounted on the outside of the capacitive sensing network, and the current-shielded twisted pair cable is placed on the terminal block and connected to the coil body. The current-shielded twisted pair cable is used to output the current signal.
[0012] The coil body includes a toroidal iron core, a secondary winding, and a sampling resistor, wherein the secondary winding is wound on the toroidal iron core, and the sampling resistor is connected in parallel across the two ends of the secondary winding.
[0013] The toroidal core is made of silicon steel sheets or amorphous alloy high magnetic permeability material.
[0014] The secondary winding is an insulated enameled wire winding, and is connected to the current-shielded twisted pair through two leads. The shielding layer of the current-shielded twisted pair is connected to the grounding terminal, which is located on the terminal block.
[0015] The space between the capacitive sensing mesh and the conductive rod, as well as the space between the capacitive sensing mesh and the current measuring module, is filled with epoxy resin to achieve mutual insulation.
[0016] The capacitive sensing mesh is a metal mesh structure.
[0017] The epoxy resin shell includes a cone, a flange, and a cylindrical body arranged sequentially along the axial direction. The flange has a sealing groove on its mounting surface, and one side of the flange extends radially to form the junction box. The cylindrical body is used to pass through the ring main unit mounting hole. The mounting surface of the flange is connected to the ring main unit mounting surface and sealed by a sealing ring.
[0018] Both ends of the conductive rod are provided with threaded holes.
[0019] The advantages and beneficial effects of this utility model are as follows: This utility model provides an integrated bushing-type electronic current transformer that integrates current measurement and capacitance status monitoring into one function. It uses epoxy resin to form a fully sealed bushing structure, and its shape adopts an external cone conforming to bushing standards, a flange plate with a sealing groove, and a near-cylindrical design. It can directly replace the standard bushing of the ring main unit without modification and can be directly installed. This solves the problems of traditional current transformers occupying a large space and being difficult to adapt to compact cabinets, greatly reducing the difficulty and cost of modification. It also has the characteristics of being resistant to moisture and dirt and requiring no maintenance throughout its lifespan. At the same time, the capacitance sensing network can monitor the epoxy resin insulation status in real time to warn of deterioration risks. The current signal is output through shielded twisted pair cable combined with high-permeability magnetic core technology, which can maintain high accuracy in complex electromagnetic environments. It also saves the cost of purchasing an independent CT and expanding the cabinet, thus maximizing cost-effectiveness.
[0020] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.
[0021] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0022] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings:
[0023] Figure 1 This is a schematic diagram of the structure of an integrated bushing-type electronic current transformer according to this utility model;
[0024] Figure 2 for Figure 1 AA section view;
[0025] Figure 3 This is a front view of an integrated bushing-type electronic current transformer according to this utility model.
[0026] Figure 4 for Figure 3 The left view;
[0027] Figure 5 This is a circuit diagram of the current measurement module in this utility model;
[0028] Figure 6 This is the wiring circuit diagram for the current-shielded twisted pair cable in this utility model.
[0029] The components are: 1. Epoxy resin shell; 4. Sealing groove; 5. Conductive rod; 6. Capacitive sensing mesh; 7. Ring core; 8. Secondary winding; 9. Sampling resistor; 10. Current shielded twisted pair; 11. Capacitor terminal; 12. Grounding terminal; 13. Shielded wire; 101. Cone; 102. Flange plate; 103. Cylindrical-like shape. Detailed Implementation
[0030] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0031] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.
[0032] See Figures 1 to 4 As shown, this utility model provides an integrated bushing-type electronic current transformer, including an insulating encapsulation structure and a conductive rod 5, a current measurement module, and a capacitance monitoring module encapsulated within the insulating encapsulation structure. The insulating encapsulation structure is an epoxy resin shell 1 cast into a fully sealed sleeve shape using epoxy resin. A terminal block is provided on the side of the epoxy resin shell 1. The conductive rod 5 axially penetrates the insulating encapsulation structure, with both ends exposed. The capacitance monitoring module includes a capacitance terminal block 11 and a cylindrical capacitance sensing mesh 6. The capacitance sensing mesh 6 is fitted outside the conductive rod 5, and the capacitance sensing mesh 6 and the conductive rod 5 constitute a monitoring capacitor for outputting a capacitance signal reflecting the dielectric state of the epoxy resin. The capacitance terminal block 11 is located on the terminal block and connected to the capacitance sensing mesh 6, allowing the capacitance to be output externally. The current measurement module includes a coil body and a current-shielded twisted pair 10. The coil body is fitted outside the capacitance sensing mesh 6, and the current-shielded twisted pair 10 is located on the terminal block and connected to the coil body, used for outputting a current signal.
[0033] See Figure 1 As shown in the embodiment of this utility model, the coil body includes an annular iron core 7, a secondary winding 8, and a sampling resistor 9, wherein the secondary winding 8 is wound on the annular iron core 7, and the sampling resistor 9 is connected in parallel to both ends of the secondary winding 8.
[0034] Furthermore, the toroidal core 7 is a toroidal structure, using silicon steel sheets or amorphous alloy high-permeability materials, with a protective outer shell for the amorphous alloy. The secondary winding 8 is an insulated enameled wire winding, with enameled wire evenly wound on the outside of the toroidal core 7. The surface of the enameled wire has an insulating varnish layer, forming insulation between each turn. The even winding of the enameled wire ensures a uniform magnetic field distribution in the secondary winding 8. The two ends of the enameled wire extend outward from the outer side of the secondary winding 8 as terminals S1 and S2, respectively. A sampling resistor 9 is connected in parallel between terminals S1 and S2. The current signal is output through a current-shielded twisted pair 10. The shielding layer of the current-shielded twisted pair 10 is connected to the grounding terminal 12 through a shielded wire 13. The grounding terminal 12 is located on the terminal block. See [reference needed]. Figure 5 and Figure 6 As shown.
[0035] Specifically, the current-shielded twisted pair 10 is a two-core shielded cable, with the two cores twisted together to form a twisted pair. The twisted pair is covered with a metal braided mesh shielding layer as a shielding wire. The two ends of the secondary winding 8 are connected to the two cores at one end of the current-shielded twisted pair 10, and the shielding wire 13 is connected to the grounding terminal 12. The current signal is transmitted through the current-shielded twisted pair 10.
[0036] Furthermore, epoxy resin is filled between the capacitive sensing mesh 6 and the conductive rod 5, as well as between the capacitive sensing mesh 6 and the current measurement module, to achieve mutual insulation.
[0037] Specifically, the capacitive sensing mesh 6 is a metal mesh structure, with a wire leading out and connected to the capacitor terminal 11. The capacitive sensing mesh 6 is separated from the current measurement module by epoxy resin to maintain insulation. The outer wall of the conductive rod 5 and the inner wall of the capacitive sensing mesh 6 form two parallel capacitor plates, with epoxy resin between the plates, constituting a capacitor that monitors the state of the epoxy resin insulating medium. The signal from this capacitor can be measured at the capacitor terminal 11.
[0038] See Figures 1 to 4 As shown in the embodiment of this utility model, the epoxy resin shell 1 includes a cone 101, a flange plate 102, and a near-cylinder 103 arranged sequentially along the axial direction. The flange plate 102 has a sealing groove 4 on its mounting surface for installing a sealing ring. One side of the flange plate 102 extends radially to form a terminal block. The near-cylinder 103 is a regular, approximately cylindrical shape, facilitating installation through openings in the switchgear. The mounting surface of the flange plate 102 can be fixed and sealed to the mounting surface of the switchgear. The cone 101 is an outer cone conforming to standard dimensions, allowing connection to a standard equipment cone sleeve.
[0039] The epoxy resin shell 1 is integrally cured and molded from epoxy resin insulating material, which encapsulates and fixes the conductive rod 5, current measurement module, and capacitance monitoring module, forming a fully sealed, maintenance-free integrated structure. During the curing process, reliable insulation between electrical components and between components and the shell is ensured.
[0040] Specifically, the conductive rod 5 is a rod-shaped metal conductor that passes through the epoxy resin shell 1 at its central axis. Both ends of the conductive rod 5 have threaded holes. The two ends of the conductive rod 5 serve as the inflow and outflow terminals of the current transformer, namely, terminal P1 and terminal P2, respectively. (See [reference]). Figure 5 and Figure 6 As shown.
[0041] This utility model provides an integrated bushing-type electronic current transformer, the working principle of which is as follows:
[0042] Current measurement: Based on the principle of low power current coil (LPCT), the current measurement module uses the toroidal iron core 7 to induce a primary current, which in turn induces a secondary small current in the secondary winding 8. This secondary current is then converted into a low-voltage small signal by the sampling resistor 9 connected in parallel across the two ends of the secondary winding 8, making its secondary output a voltage signal. The phase of the voltage signal is consistent with that of the primary current, and the amplitude is proportional to the amplitude of the primary current. The secondary signal is output through the current shielded twisted pair cable 10, which provides strong anti-interference capability and high signal accuracy.
[0043] Capacitance monitoring: A cylindrical capacitance sensing mesh 6 is arranged coaxially around the conductive rod 5. The capacitance sensing mesh 6 and the conductive rod 5 together form a monitoring capacitor, which is used to sense and output the capacitance value that reflects the state of the insulating medium.
[0044] All the above components are integrally cured and molded using epoxy resin insulation material, forming a fully sealed, maintenance-free integrated structure. This integrates the current transformer and the capacitor status monitoring bushing, facilitating installation and reducing space requirements. The internal components are arranged in an orderly manner to avoid electromagnetic interference, resulting in a small output voltage signal that does not interfere with each other, and superior performance. The transformer's shape is designed as a standard bushing: the front end is a cone 101 of standard bushing dimensions, the middle is a flange plate 102 with a sealing groove, and the rear end is a near-cylinder 103 for easy installation and insertion.
[0045] This utility model integrates current measurement and capacitance status monitoring functions, with a highly compact structure. It can directly replace the standard bushings in equipment such as ring main units for installation, and is particularly suitable for the automation transformation of compact ring main units in space-constrained scenarios. It solves the problems of difficult installation and high cost of traditional current transformers.
[0046] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this utility model and their equivalents, this utility model also intends to include these modifications and variations.
Claims
1. An integrated bushing-type electronic current transformer, characterized by, The application relates to an insulating packaging structure and a conductive rod, a current measuring module and a capacitance monitoring module packaged in the insulating packaging structure, wherein the insulating packaging structure is an epoxy resin shell in a full-sealing sleeve shape formed by pouring epoxy resin, a wiring platform is arranged on the side surface of the epoxy resin shell, the conductive rod axially penetrates the insulating packaging structure and is exposed at both ends. The capacitance monitoring module comprises a capacitance wiring terminal and a cylindrical capacitance induction net, the capacitance induction net is sleeved outside the conductive rod, the capacitance induction net and the conductive rod form a monitoring capacitor for outputting a capacitance signal reflecting the dielectric state of the epoxy resin, the capacitance wiring terminal is arranged on the wiring platform and is connected with the capacitance induction net. The current measuring module comprises a coil body and a current shielding double-twisted wire, the coil body is sleeved outside the capacitance induction net, the current shielding double-twisted wire is arranged on the wiring platform and is connected with the coil body, and the current shielding double-twisted wire is used for outputting a current signal.
2. The integrated bushing-type electronic current transformer of claim 1, wherein, The coil body comprises an annular core, a secondary winding and a sampling resistor, the secondary winding is wound on the annular core, and the sampling resistor is connected in parallel with both ends of the secondary winding.
3. The integrated bushing-type electronic current transformer of claim 2, wherein, The annular core is made of silicon steel sheet or amorphous alloy high-permeability magnetic material.
4. The integrated bushing-type electronic current transformer of claim 2, wherein, The secondary winding is an insulating enamel wire winding and is connected with the current shielding double-twisted wire through two lead-out wires, the shielding layer of the current shielding double-twisted wire is connected with a grounding terminal, and the grounding terminal is arranged on the wiring platform.
5. The integrated bushing-type electronic current transformer of claim 1, wherein, The capacitance induction net and the conductive rod and the capacitance induction net and the current measuring module are filled with epoxy resin to realize mutual insulation.
6. The integrated bushing-type electronic current transformer of claim 1, wherein, The capacitance induction net is a metal net structure.
7. The integrated bushing-type electronic current transformer of claim 1, wherein, The epoxy resin shell comprises a circular cone, a flange plate and a quasi-cylindrical body arranged in sequence along the axial direction, a mounting surface of the flange plate is provided with a sealing groove, one side of the flange plate extends along the radial direction to form the wiring platform, the quasi-cylindrical body is used for penetrating a looped net cabinet installation hole, the mounting surface of the flange plate is connected with a looped net cabinet mounting surface and is sealed through a sealing ring.
8. The integrated bushing-type electronic current transformer of claim 1, wherein, Both ends of the conductive rod are provided with threaded holes.