High-efficiency three-phase five-column voltage transformer for ring main unit

Abstract

The utility model relates to the technical field of mutual inductor, and disclose a kind of efficient three-phase five-column voltage mutual inductor for ring main unit, including insulating shell, the inside of insulating shell is penetrated with center column core, double column assembly, outgoing line column, the outside of insulating shell is provided with fusing assembly, the front side of insulating shell is provided with terminal box, the bottom end of the center column core, the double column assembly and the outgoing line column is fixedly connected with iron core main body. Through the double column assembly structure of core, the winding two of double column body outside are cooperated with top bifurcated double column, both can participate in three-phase voltage conversion to guarantee basic power supply monitoring, and can construct zero sequence magnetic flux path using bifurcated double column when system grounding fault, make winding two induction zero sequence signal, provide reliable basis for grounding protection, give consideration to conventional voltage measurement and fault protection function, center column core, double column assembly and outgoing line column bottom end unified fixed connection iron core main body, form stable magnetic circuit system.

Description

Technical Field

[0001] This utility model relates to the field of transformer technology, specifically a high-efficiency three-phase five-limb voltage transformer for ring main units. Background Technology

[0002] Traditional voltage transformers lack a dedicated zero-sequence magnetic flux path design, making it impossible to sense zero-sequence signals during system grounding faults. This necessitates additional grounding protection devices, increasing costs and installation complexity. Furthermore, device coordination issues can lead to protection delays and fault escalation. Loose connections between the core column and the iron core, along with magnetic flux leakage and losses between the primary winding and the core column, result in decreased high-to-low voltage conversion accuracy and significant secondary-side output signal deviations, potentially causing misjudgments in ring main unit monitoring or malfunctions in protection systems. Poor overall structural adaptability and ease of maintenance, coupled with large product size and dispersed component layout, make them difficult to fit into the compact installation space of ring main units and prone to interference with other equipment. This increases maintenance workload, may prolong power outage time, and affects the continuous and stable operation of the power supply system. Utility Model Content

[0003] The purpose of this utility model is to solve the problems of magnetic flux loss and reduced transformation accuracy caused by the lack of a dedicated zero-sequence magnetic flux path in traditional voltage transformers, the need for additional grounding protection devices, loose connection between the core column and the iron core, and improper primary winding coordination. This utility model provides a high-efficiency three-phase five-column voltage transformer for ring main units.

[0004] To achieve the above objectives, this utility model specifically adopts the following technical solution: A high-efficiency three-phase five-column voltage transformer for ring main units includes an insulating shell. A central column, a double-column assembly, and a lead-out column are passed through the inner side of the insulating shell. A fuse assembly is provided on the outer side of the insulating shell. A terminal box is provided on the front side of the insulating shell. An iron core body is fixedly connected to the bottom end of the central column, the double-column assembly, and the lead-out column. A primary winding is wound on the outer side of the insulating shell.

[0005] Furthermore, the insulating shell includes an iron core area, a central sleeve, an inlet end, and an outlet end. The central sleeve, the inlet end, and the outlet end are located at the top of the iron core area. In this case, the silicone rubber shed wrapped with vulcanized silicone rubber on the outer wall of the inlet end, the outlet end, and the central sleeve increases the creepage distance and avoids flashover caused by air breakdown under high voltage.

[0006] Furthermore, the central core includes a central core column and a secondary winding. The secondary winding is wound around the outer wall of the secondary winding. The three-phase high-voltage current flowing through the primary winding generates a symmetrical alternating magnetic flux. The magnetic flux enters the central core column, the double column, and the output column body through the iron core body.

[0007] Furthermore, the dual-column assembly includes a dual column, a second winding, and a forked dual column. The second winding is wound around the outside of the dual column, and the forked dual column is located at the top of the dual column. During normal operation, the forked dual column has no zero-sequence magnetic flux, and the second winding has no signal output. During a ground fault, the zero-sequence magnetic flux passes through the forked dual column, causing the second winding to induce a zero-sequence voltage signal. This signal is connected to the ground protection relay via the terminal box.

[0008] Furthermore, the outgoing column and the double column assembly have the same structure, and the forked double columns at the top of the two main core columns (double columns, outgoing column body) serve as "side columns".

[0009] Furthermore, the fuse assembly includes a fuse and a lead wire. The bottom end of the lead wire is located at the top end of the fuse. The silver-copper alloy fuse element of the fuse melts under the rated current, cutting off the primary high-voltage circuit through the lead wire, thus preventing the fault current from burning out the transformer body or affecting other equipment in the ring main unit.

[0010] Furthermore, the outer walls of the central sleeve, the inlet end, and the outlet end are all vulcanized and wrapped with silicone rubber skirts to prevent flashover caused by air breakdown under high voltage; and to isolate external environmental factors such as moisture and dust.

[0011] Furthermore, the core column is made of 30Q130 oriented silicon steel sheets stacked together, and the outer wall is wrapped with epoxy glass cloth tube as an insulating bushing. The high permeability of the oriented silicon steel sheets can reduce hysteresis loss, while the outer epoxy glass cloth tube (insulating bushing) isolates the core column from the secondary winding to prevent high voltage from entering the low voltage side.

[0012] Compared with the prior art, this utility model provides a high-efficiency three-phase five-limb voltage transformer for ring main units, which has the following advantages: This ring main unit uses a high-efficiency three-phase five-column voltage transformer. Through its core double-column assembly structure, the second winding wound on the outer side of the double columns, together with the bifurcated double columns at the top, can participate in three-phase voltage transformation to ensure basic power supply monitoring. Furthermore, in the event of a system ground fault, the bifurcated double columns can construct a zero-sequence magnetic flux path, allowing the second winding to induce a zero-sequence signal, providing a reliable basis for grounding protection. It combines conventional voltage measurement with fault protection functions. The central column core, double-column assembly, and the bottom of the outgoing columns are uniformly and fixedly connected to the iron core body, forming a stable magnetic circuit system and reducing magnetic flux loss. Combined with the primary winding wound on the outer side of the insulating shell, it can efficiently achieve precise high-voltage to low-voltage conversion, ensuring the accuracy of secondary side measurement or protection signals. The overall structure is adapted to the compact installation space of the ring main unit, balancing high efficiency, safety protection, and convenient operation and maintenance, thus improving the stability and reliability of the ring main unit power supply system. Attached Figure Description

[0013] Figure 1 A three-dimensional view of the overall external structure of this utility model is provided. Figure 2 A three-dimensional diagram showing the overall structure of this utility model without the insulating outer shell; Figure 3 The right side shows a three-dimensional view illustrating the structure of this practical double-column assembly. Figure 4 A three-dimensional view of the central column core assembly of this utility model is provided. Figure 5 A three-dimensional view showing the inside of the insulating shell of this utility model cut open.

[0014] In the diagram: 1. Insulating outer shell; 11. Iron core area; 12. Center sleeve; 13. Inlet terminal; 14. Outlet terminal; 2. Center column core; 21. Center core column; 22. Secondary winding; 3. Double column assembly; 31. Double column body; 32. Winding two; 33. Forked double column; 4. Outlet column; 5. Fuse assembly; 51. Fuse; 52. Lead wire; 6. Terminal box; 7. Iron core body; 8. Primary winding. Detailed Implementation

[0015] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model. Example 1:

[0016] like Figure 5 As shown, a high-efficiency three-phase five-limb voltage transformer for ring main units includes an insulating shell 1. The insulating shell 1 includes an iron core area 11, a central sleeve 12, an inlet terminal 13, and an outlet terminal 14. The central sleeve 12, the inlet terminal 13, and the outlet terminal 14 are located at the top of the iron core area 11. The outer walls of the central sleeve 12, the inlet terminal 13, and the outlet terminal 14 are all vulcanized and wrapped with silicone rubber skirts to prevent flashover caused by air breakdown under high voltage. It can isolate external environmental factors such as moisture and dust, ensure the insulation reliability when high voltage is connected, and prevent leakage risk. like Figure 4 As shown, the inner side of the insulating shell 1 is permeated by the central core 2, the double-column assembly 3, and the outgoing column 4. The central core 2 includes a central core column 21 and a secondary winding 22. The secondary winding 22 is wound around the outer wall of the secondary winding 22. The three-phase high-voltage current flowing through the primary winding 8 generates a symmetrical alternating magnetic flux. The magnetic flux enters the central core column 21, the double-column assembly 31, and the outgoing column body (three main core columns) through the iron core body 7. Among them, the core column 21 is made of 30Q130 oriented silicon steel sheets, and the outer wall is wrapped with epoxy glass cloth tube as an insulating bushing. The high permeability of the oriented silicon steel sheets can reduce hysteresis loss, and the outer epoxy glass cloth tube (insulating bushing) isolates the core column 21 from the secondary winding 22 to prevent high voltage from entering the low voltage side. Example 2:

[0017] like Figure 3 As shown, the dual-column assembly 3 includes a dual-column body 31, a second winding 32, and a forked dual-column 33. The second winding 32 is wound on the outside of the dual-column body 31, and the forked dual-column 33 is located at the top of the dual-column body 31. The output post 4 has the same structure as the dual-column assembly 3. The second winding 32 on the outside of the dual-column body 31 and the open delta winding of the forked dual-column 33 work together: During normal operation, the forked dual-column 33 has no zero-sequence magnetic flux, and the second winding 32 has no signal output; During a ground fault, the zero-sequence magnetic flux passes through the forked dual-column 33, causing the second winding 32 to induce a zero-sequence voltage signal. like Figure 1 and Figure 2 As shown, a fuse assembly 5 is provided on the outer side of the insulating shell 1, a terminal box 6 is provided on the front side of the insulating shell 1, and an iron core body 7 is fixedly connected to the bottom of the central core 2, the double core assembly 3 and the outgoing core 4. A primary winding 8 is wound on the outer side of the insulating shell 1.

[0018] Working principle: such as Figures 1-5 As shown, the high-voltage busbar of the ring main unit is connected to the current transformer through the inlet terminal 13 of the insulating shell 1. At this time, the silicone rubber umbrella skirts wrapped with vulcanized outer walls of the incoming terminal 13, the outgoing terminal 14, and the center sleeve 12 increase the creepage distance and avoid flashover caused by air breakdown under high voltage; they can also isolate external environmental factors such as moisture and dust, ensure the insulation reliability when high voltage is connected, and prevent leakage risk. High-voltage electrical energy is transmitted through the incoming terminal 13 to the primary winding 8 wound on the outside of the insulating shell 1. The primary winding is made of copper enameled wire, which withstands high voltage and establishes an initial alternating magnetic field. The alternating magnetic flux generated after the primary winding 8 is energized is introduced into the "three-phase five-column magnetic circuit system" inside the transformer through the iron core body 7. This system consists of "the central core column 21 of the central core 2 + the double column 31 of the double column assembly 3 + the output column 4 (with the same structure as the double column assembly)", corresponding to the "three main core columns" of the three-phase five-column system. The bifurcated double column 33 at the top of the two main core columns (double column 31 and output column body) undertakes the function of "side column". During operation (three-phase voltage symmetrical): The three-phase high-voltage current flowing through the primary winding 8 generates symmetrical alternating magnetic flux, which enters the core column 21, the double column 31, and the outgoing column body (three main core columns) through the iron core body 7 respectively. Among them, the core column 21 is made of 30Q130 oriented silicon steel sheets. The high permeability of the oriented silicon steel sheets can reduce hysteresis loss. The outer epoxy glass cloth tube (insulating bushing) isolates the core column 21 from the secondary winding 22 to prevent high voltage from entering the low voltage side. During a ground fault (three-phase voltage asymmetry): When a single-phase ground fault occurs in the ring main unit power supply system, the three-phase voltage imbalance generates a "zero-sequence voltage". At this time, the magnetic flux of the three-phase main core column is no longer zero. The excess zero-sequence magnetic flux cannot be closed through the conventional main magnetic circuit. Instead, it forms a loop through the bifurcated double column 33 at the top of the two main core columns (the zero-sequence column of the bifurcated double column provides a dedicated path for the magnetic flux), creating conditions for the subsequent ground protection signal output. When the magnetic flux is transmitted in the three main core columns, it couples with the low-voltage windings wound on the outside of the core columns, realizing the "high voltage → low voltage" transformation through electromagnetic induction, and outputting two types of core signals: Measurement signal output (secondary winding 22 of the center column 2): The secondary winding 22 outside the center column 21 is divided into an inner measuring winding and an outer protective winding: The measuring winding converts the 10kV high voltage on the primary side into a 100V standard low voltage signal according to the transformation ratio through electromagnetic induction. The signal is transmitted to the terminal box 6 through the wire, and then connected to the voltmeter, energy meter and other measuring instruments of the ring network cabinet to realize real-time monitoring of the grid voltage. Grounding protection signal output (winding 32 of the double column assembly 3): The winding 32 on the outer side of the double column 31 works in conjunction with the open delta winding of the bifurcated double column 33: During normal operation, the bifurcated double column 33 has no zero-sequence magnetic flux, and the winding 32 has no signal output; during a grounding fault, the zero-sequence magnetic flux passes through the bifurcated double column 33, causing the winding 32 to induce a zero-sequence voltage signal. This signal is connected to the grounding protection relay through the terminal box 6, triggering the fault isolation action (such as tripping) of the ring main unit to prevent the fault from escalating. When an extreme fault such as a short circuit or overcurrent occurs inside the transformer, the fault current will increase rapidly. At this time, the fuse assembly 5 located on the outside of the insulating shell 1 will respond immediately: the silver-copper alloy fuse element of the fuse 51 will melt under the rated current, and the primary high voltage circuit will be cut off through the lead wire 52 to prevent the fault current from burning the transformer body or affecting other equipment in the ring main unit. Core loss control: The core column 21 and the double column 31 are made of 30Q130 oriented silicon steel sheets, whose low iron loss characteristics can reduce hysteresis loss and eddy current loss, and lower the operating temperature of the transformer.

Claims

1. A high-efficiency three-phase five-limb voltage transformer for ring main units, comprising an insulating shell (1), characterized in that: The inner side of the insulating shell (1) is permeated by the central core (2), the double-column assembly (3), and the outgoing column (4). The double-column assembly (3) includes a double column (31), a second winding (32), and a forked double column (33). The second winding (32) is wound around the outside of the double column (31), and the forked double column (33) is disposed at the top of the double column (31). A fuse assembly (5) is provided on the outside of the insulating shell (1), a terminal box (6) is provided on the front side of the insulating shell (1), and an iron core body (7) is fixedly connected to the bottom of the central core (2), the double core assembly (3) and the outgoing core (4). A primary winding (8) is wound on the outside of the insulating shell (1).

2. The high-efficiency three-phase five-limb voltage transformer for ring main units according to claim 1, characterized in that: The insulating shell (1) includes an iron core area (11), a central sleeve (12), an inlet end (13) and an outlet end (14), wherein the central sleeve (12), the inlet end (13) and the outlet end (14) are disposed at the top of the iron core area (11).

3. The high-efficiency three-phase five-limb voltage transformer for ring main units according to claim 1, characterized in that: The central core (2) includes a central core (21) and a secondary winding (22), the secondary winding (22) being wound around the outer wall of the secondary winding (22).

4. The high-efficiency three-phase five-limb voltage transformer for ring main units according to claim 1, characterized in that: The outgoing column (4) and the double column assembly (3) have the same structure.

5. A high-efficiency three-phase five-limb voltage transformer for ring main units according to claim 1, characterized in that: The fuse assembly (5) includes a fuse (51) and a lead wire (52), with the bottom end of the lead wire (52) disposed at the top end of the fuse (51).

6. A high-efficiency three-phase five-limb voltage transformer for ring main units according to claim 1, characterized in that: The outer walls of the central sleeve (12), the inlet end (13), and the outlet end (14) are all vulcanized and wrapped with silicone rubber skirts.

7. A high-efficiency three-phase five-limb voltage transformer for ring main units according to claim 1, characterized in that: The central core (21) is made of stacked 30Q130 oriented silicon steel sheets, and the outer wall is wrapped with epoxy glass cloth tube as an insulating bushing.

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