Zero sequence current transformer

Abstract

The utility model relates to a zero sequence current transformer, and belongs to the technical field of transformer manufacturing. According to the technical scheme, a secondary winding (6) is wound on an iron core (4), the secondary winding (6) is a first secondary winding (1), a second secondary winding (2) and a third secondary winding (3) which are connected in parallel, the number of turns of the three secondary windings is the same, the winding direction of the three secondary windings is the same, and the number of turns of the three secondary windings is evenly distributed, and a metal shielding shell (8) and a shielding winding (10) are arranged outside the secondary winding (6). The shielding winding is divided into four sections of windings which are equal in number of turns, same in winding direction and uniform in number of turns, starting ends of the four sections of windings are connected together, and tail ends of the four sections of windings are connected together. The zero sequence current transformer has the advantages that secondary output is not affected by position changes of the primary cross-core wire, electromagnetic interference of various electrified bodies on the periphery of the outside is effectively reduced, and accuracy and stability of the zero sequence current transformer are guaranteed.

Description

Technical Field

[0001] The utility model relates to a zero-sequence current transformer, in particular to an anti-interference zero-sequence current transformer, belonging to the technical field of current transformer manufacturing. Background Art

[0002] A zero-sequence current transformer (CCT) is a current transformer specifically designed to transform zero-sequence current. In power systems, CCTs are typically used in conjunction with relay protection devices. When a zero-sequence ground current (or ground fault) is generated in the line, the device components are selectively tripped or signaled to protect or detect normal line operation. In a CCT, the primary system's A, B, and C phase conductors are typically routed simultaneously through an internal window. When the primary system current is high or the voltage is high, the A, B, and C phase busbars are often arranged side by side, while the CCT is designed in a runway or rectangular shape. Furthermore, the CCT's secondary output current (or voltage) is relatively small, making it susceptible to electromagnetic interference. The zero-sequence current transformer is easily affected by the position of the A, B, and C phase busbars and the electromagnetic interference of various charged bodies in the external surroundings, resulting in unstable secondary output data of the current transformer and failure to accurately feed back primary circuit information to the secondary protection device, which can easily cause "false operation" or "refusal to operate" and make the protection device unable to achieve accurate protection and monitoring functions, endangering equipment and human safety. Utility Model Content

[0003] The purpose of the utility model is to provide a zero-sequence current transformer, so that the electrical performance of the zero-sequence current transformer is not interfered with by other factors during operation, greatly improving the accuracy and stability of the zero-sequence current transformer, avoiding the phenomenon of "false operation" or "refusal to operate" of the relay protection device due to inaccurate and unstable output of the zero-sequence current transformer, ensuring the safety of equipment and personnel, and also ensuring the stability and safety of the power system operation, solving the above-mentioned technical problems existing in the background technology.

[0004] The utility model proposes the following technical solutions:

[0005] A zero-sequence current transformer comprises an iron core, a secondary winding, a metal shielding shell and a shielding winding. The iron core is wound with a secondary winding. The secondary winding is composed of three secondary windings with the same number of turns, the same winding direction and evenly distributed turns connected in parallel, namely secondary winding one, secondary winding two and secondary winding three. A metal shielding shell and a shielding winding are provided outside the secondary winding.

[0006] The shielding winding is divided into four sections of windings with equal number of turns, same winding direction and evenly distributed number of turns. The starting ends of the four sections of windings are connected together, and the ending ends of the four sections of windings are connected together.

[0007] The core shape is a racetrack shape or a rectangle.

[0008] The secondary winding one is located on the left side of the iron core; the secondary winding two is located in the middle of the iron core, and the secondary winding two is divided into two parts with equal number of turns, which are located in the upper half of the middle part and the lower half of the middle part of the iron core respectively. The two parts are connected in series to form the secondary winding two; the secondary winding three is located on the right side of the iron core.

[0009] The iron core is provided with an insulating layer 1, and a secondary winding is provided outside the insulating layer 1. The secondary winding is provided with an insulating layer 2 outside the secondary winding, and a metal shielding shell is provided outside the insulating layer 2. The iron core and secondary winding of the zero-sequence current transformer are protected within the metal shielding shell. The metal shielding shell can be made of silicon steel laminates, stainless steel, copper, aluminum, or other materials.

[0010] An insulating layer three is arranged outside the metal shielding shell, and a shielding winding is wound outside the insulating layer three.

[0011] A fourth insulating layer is provided outside the shielding winding, and a layer of epoxy resin is poured on the outermost surface.

[0012] The beneficial effects of the present invention are as follows: three secondary windings with the same number of turns, the same winding direction, and uniform distribution are wound on the same iron core at the same time, and used in parallel, which can ensure that their own electrical performance is not affected by changes in the position of the primary through-core conductor, and the secondary output is stable. At the same time, a metal shielding shell and a shielding winding are provided to improve the anti-electromagnetic interference capability of the zero-sequence current transformer, and effectively reduce the electromagnetic interference of various external charged bodies on the zero-sequence current transformer. The electrical performance of the zero-sequence current transformer is not affected by other factors during operation, which greatly improves the accuracy and stability of the zero-sequence current transformer, avoids the phenomenon of "false operation" or "refusal to operate" of the relay protection device due to inaccurate and unstable output of the zero-sequence current transformer, ensures the safety of equipment and personnel, and also ensures the stability and safety of the power system operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the runway-shaped structure of the first embodiment of the present utility model;

[0014] Figure 2 This is a schematic diagram of the rectangular structure of the second embodiment of the present utility model;

[0015] Figure 3 This is a schematic diagram of the secondary winding of an embodiment of the utility model;

[0016] Figure 4 This is a schematic diagram of the shielding winding of an embodiment of the present utility model;

[0017] Figure 5 It is a cross-sectional view of an embodiment of the utility model;

[0018] In the figure: secondary winding one 1, secondary winding two 2, secondary winding three 3, iron core 4, insulation layer one 5, secondary winding 6, insulation layer two 7, metal shielding shell 8, insulation layer three 9, shielding winding 10, insulation layer four 11, epoxy resin 12. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. The following is a further explanation of the present invention through embodiments in conjunction with the drawings.

[0020] A zero-sequence current transformer includes an iron core 4, a secondary winding 6, a metal shielding shell 8 and a shielding winding 10. The secondary winding 6 is wound on the iron core 4. The secondary winding 6 is composed of three secondary windings with the same number of turns, the same winding direction, and uniformly distributed turns connected in parallel, namely secondary winding 1, secondary winding 2 and secondary winding 3. A metal shielding shell 8 and a shielding winding 10 are provided outside the secondary winding 6.

[0021] The shielding winding is divided into four sections of windings with equal number of turns, same winding direction and evenly distributed number of turns. The starting ends of the four sections of windings are connected together, and the ending ends of the four sections of windings are connected together.

[0022] The core 4 is in a racetrack or rectangular shape.

[0023] The secondary winding 1 is located on the left side of the iron core 4; the secondary winding 2 is located in the middle of the iron core, and the secondary winding 2 is divided into two parts with equal number of turns, which are located in the upper half of the middle part and the lower half of the middle part of the iron core respectively. The two parts are connected in series to form the secondary winding 2; the secondary winding 3 is located on the right side of the iron core.

[0024] The secondary winding 1 1, secondary winding 2 2 and secondary winding 3 3 are evenly distributed on the iron core, each occupying one-third of the iron core. The number of turns of the secondary winding 1 1, secondary winding 2 2 and secondary winding 3 3 is also evenly distributed. The secondary winding 1 1, secondary winding 2 2 and secondary winding 3 3 are connected in parallel, and the connected starting and ending ends serve as the secondary output end of the zero-sequence current transformer.

[0025] An insulating layer 1 5 is provided outside the iron core 4, and a secondary winding 6 is provided outside the insulating layer 1 5. An insulating layer 2 7 is provided outside the secondary winding 6, and a metal shielding shell 8 is provided outside the insulating layer 2 7. The iron core and secondary winding of the zero-sequence current transformer are protected within the metal shielding shell. The metal shielding shell can be made of silicon steel laminates, stainless steel, copper, aluminum, or other materials.

[0026] The metal shielding shell 8 is provided with an insulating layer 3 9 on the outside, and a shield winding 10 is wound around the outside of the insulating layer 3 9. The shield winding consists of four sections with the same number of turns and the same winding direction. The four sections are evenly distributed throughout the core, and the starting and ending ends of the four sections are connected together, that is, the four sections are connected in parallel.

[0027] An insulating layer 11 is provided outside the shielding winding 10, and a layer of epoxy resin 12 is poured on the outermost surface.

[0028] Example 1, refer to the attached Figure 1 , the shape of the core 4 is a racetrack shape.

[0029] Example 2, refer to the attached Figure 2 , the core 4 is rectangular in shape.

[0030] See also Figure 1-5 Secondary winding 1 starts at 1S1 and ends at 1S2. Secondary winding 2 is divided into two parts with the same number of turns: the lower part starts at 2S1 and ends at 2L1, while the upper part starts at 2L2 and ends at 2S2. 2L1 and 2L2 are connected together to form secondary winding 2. Secondary winding 3 starts at 3S1 and ends at 3S2. Secondary winding 1, secondary winding 2, and secondary winding 3 are connected in parallel, connecting 1S1, 2S1, and 3S1 together, and 1S2, 2S2, and 3S2 together, to form the secondary output of the zero-sequence current transformer. An insulating layer 2 7 is wound around the outside of secondary winding 6, and a metal shielding case 8 is provided outside of insulating layer 2 7. An insulating layer 3 9 is wound around the outside of metal shielding case 8, and a shielded winding 10 is wound around the outside of insulating layer 3 9. The shield winding 10 is divided into four evenly spaced sections with the same number of turns and the same winding direction. The starting and ending sections are S1, S1', S2, S2', S3, S3', S4, and S4'. S1, S2, S3, and S4 are connected together, and S1', S2', S3', and S4' are connected together. An insulating layer 11 is wound around the outside of the shield winding 10. Epoxy resin 12 can be poured over the insulating layer 11.

[0031] This zero-sequence current transformer ensures its electrical performance is unaffected by changes in the primary lead position, ensuring stable secondary output. The metal shielding case and shielded windings also enhance the zero-sequence current transformer's electromagnetic interference resistance, effectively reducing electromagnetic interference from various external live objects.

Claims

1. A zero-sequence current transformer, characterized in that: The invention comprises an iron core (4), a secondary winding (6), a metal shielding shell (8) and a shielding winding (10), wherein the iron core (4) is wound with a secondary winding (6), and the secondary winding (6) is composed of three secondary windings with the same number of turns, the same winding direction and uniformly distributed number of turns connected in parallel, namely, secondary winding one (1), secondary winding two (2) and secondary winding three (3), and a metal shielding shell (8) and a shielding winding (10) are provided outside the secondary winding (6).

2. A zero-sequence current transformer according to claim 1, characterized in that: The shielding winding is divided into four sections of windings with equal number of turns, same winding direction and evenly distributed number of turns. The starting ends of the four sections of windings are connected together, and the ending ends of the four sections of windings are connected together.

3. A zero-sequence current transformer according to claim 1 or 2, characterized in that: The shape of the core (4) is a racetrack shape or a rectangle.

4. A zero-sequence current transformer according to claim 1 or 2, characterized in that: The secondary winding 1 (1) is located on the left side of the iron core (4); the secondary winding 2 (2) is located in the middle of the iron core, and the secondary winding 2 (2) is divided into two parts with equal number of turns, which are located in the upper half of the middle part and the lower half of the middle part of the iron core respectively. The two parts are connected in series to form the secondary winding 2 (2); the secondary winding 3 (3) is located on the right side of the iron core.

5. A zero-sequence current transformer according to claim 1 or 2, characterized in that: An insulating layer 1 (5) is provided outside the iron core (4), and a secondary winding (6) is provided outside the insulating layer 1 (5); an insulating layer 2 (7) is provided outside the secondary winding (6), and a metal shielding shell (8) is provided outside the insulating layer 2 (7), protecting the iron core and the secondary winding of the zero-sequence current transformer in the metal shielding shell.

6. A zero-sequence current transformer according to claim 1 or 2, characterized in that: An insulating layer three (9) is provided outside the metal shielding shell (8), and a shielding winding (10) is wound outside the insulating layer three (9).

7. A zero-sequence current transformer according to claim 6, characterized in that: An insulating layer (11) is provided outside the shielding winding (10), and a layer of epoxy resin (12) is poured on the outermost surface.

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