Straight-through type medium-voltage current transformer

Abstract

The utility model discloses a cross-core type medium-voltage current transformer, which comprises a shell and a central hole arranged on the inner side of the shell along the axial direction of the shell, insulating materials are filled in the shell, a plurality of iron core coils are arranged in the shell, a tubular net is arranged on the inner side wall of the central hole, an equipotential line is connected on the tubular net, and the equipotential line is connected with the shell. The equipotential line extends to the inner side of the center hole, annular nets are arranged at the two ends of the shell respectively, and the two annular nets are both connected with the tubular net. According to the utility model, the annular net and the tubular net form a whole body, the electric field distribution of two end faces is effectively improved, and arc light flashover does not radially appear on the end faces during a withstand voltage test.

Description

Technical Field

[0001] The utility model belongs to the field of circuit elements, and in particular relates to a through-type medium-voltage current transformer. Background Art

[0002] At present, the demand for high current in medium voltage distribution network, including wind and solar power generation stations, is increasing. However, the existing closed pillar type 35kV current transformer has poor heat dissipation, and its temperature rise under high current conditions needs special attention. The excessive temperature rise may even exceed the glass transition temperature of epoxy cured material, which significantly reduces the mechanical strength and causes insulation failure.

[0003] A better option for monitoring and protecting high-current lines is the through-type transformer. The busbar passes directly through the center hole of the transformer. The heat generated by the busbar is dissipated through the hollow core and will not directly cause the transformer temperature to rise significantly.

[0004] For through-type medium-voltage transformers, the general structure is to add a non-magnetic tubular metal mesh on the inner wall of the center hole, and connect a wire on the mesh. When in use, the wire is connected to the busbar, so that the inner wall of the transformer and the busbar form an equal potential, avoiding electrical gaps in the center hole and discharge during operation and voltage withstand tests.

[0005] However, through experiments, it was found that simply adding an equipotential network on the inner wall does not completely solve the problem. When doing a withstand voltage test, if no ring network is added to the surface or surface of the two ends of the product, radial flashover discharge will occur along the end surface. This is not allowed. Through software simulation, it was found that when no flange-shaped ring network is added here, a higher electric field is formed on the end surface, which also explains the reason for the radial flashover to the surroundings during the withstand voltage test. Utility Model Content

[0006] The technical problem to be solved by the present invention is to provide a through-type medium-voltage current transformer in view of the deficiencies of the above-mentioned prior art, in which the annular network and the tubular network form a whole, effectively improving the electric field distribution at both end faces, and no arc flashover will appear radially on the end faces during the withstand voltage test.

[0007] The technical solution adopted by the utility model is: a through-type medium-voltage current transformer, comprising a shell and a center hole arranged on the inner side of the shell along the axial direction of the shell, the shell is filled with insulating material, a plurality of iron core coils are arranged in the shell, a tubular net is arranged on the inner wall of the center hole, equipotential lines are connected to the tubular net, the equipotential lines extend to the inner side of the center hole, annular nets are respectively arranged at both ends of the shell, and both of the annular nets are connected to the tubular net.

[0008] In one embodiment, the insulating material is epoxy resin.

[0009] In one embodiment, the core coil is disposed in the insulating material through a coil fixing member.

[0010] In one embodiment, the coil fixing member is made of non-magnetic metal.

[0011] In one of the embodiments, a connecting flange is provided in the middle portion of the outer side of the shell.

[0012] In one embodiment, the connecting flange is provided with a connecting terminal, and the connecting terminal is connected to the iron core coil.

[0013] In one of the embodiments, a first umbrella skirt and a second umbrella skirt are respectively provided on the outer side of the shell.

[0014] In one embodiment, the first umbrella skirts and the second umbrella skirts are both in two groups and are respectively arranged on both sides of the connecting flange.

[0015] The beneficial effect of the utility model is that the annular network and the tubular network form a whole, which effectively improves the electric field distribution at both end faces, and no arc flashover will appear radially on the end faces during the withstand voltage test. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the utility model;

[0017] Figure 2 It is a side view of the utility model.

[0018] In the figure: 1, shell; 2, center hole; 3, insulating material; 4, iron core coil; 5, tubular network; 6, equipotential lines; 7, annular network; 8, coil fixing parts; 9, connecting flange; 10, first umbrella skirt; 11, second umbrella skirt. DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] like Figure 1 and Figure 2 As shown, a through-type medium-voltage current transformer comprises a shell 1 and a center hole 2 arranged on the inner side of the shell 1 along the axial direction of the shell 1, the shell 1 is filled with insulating material 3, a plurality of iron core coils 4 are arranged in the shell 1, a tubular net 5 is arranged on the inner wall of the center hole 2, an equipotential line 6 is connected to the tubular net 5, and the equipotential line 6 extends to the inner side of the center hole 2, and annular nets 7 are respectively arranged at both ends of the shell 1, and both of the annular nets 7 are connected to the tubular net 5.

[0021] In this embodiment, the insulating material 3 is epoxy resin.

[0022] In this embodiment, the iron core coil 4 is disposed in the insulating material 3 through a coil fixing member 8 .

[0023] In this embodiment, the coil fixing member 8 is made of non-magnetic metal.

[0024] In this embodiment, a connecting flange 9 is provided in the middle of the outer side of the shell 1 .

[0025] In this embodiment, the connecting flange 9 is provided with a connecting terminal 12 , and the connecting terminal 12 is connected to the iron core coil 4 .

[0026] In this embodiment, a first umbrella skirt 10 and a second umbrella skirt 11 are respectively provided on the outer side of the shell 1 .

[0027] In this embodiment, the first umbrella skirts 10 and the second umbrella skirts 11 are both in two groups and are respectively arranged on both sides of the connecting flange 9 .

[0028] The through-type medium voltage current transformer, also called bushing type current transformer, is provided with a connecting flange 9 in the middle, which is installed on a support, and the high voltage current carrying busbar passes through the center hole 2 when in use.

[0029] The iron core coil 4 is the core component of the entire current transformer. When current passes through the center hole 2, a corresponding current will be induced in the iron core coil 4, which is used for monitoring the current of the power distribution device and also serves as a signal source for the action of the protection device. The number of the iron core coil 4 can be one or more, and the number and parameters are configured according to different project plans.

[0030] The coil fixing member 8 can effectively help fix the core coil 4 in the insulating material 3 when the current transformer is insulated and packaged; the material is selected from non-magnetic metal to avoid eddy current heating when large current occurs and the temperature exceeds the allowable value.

[0031] The insulating material 3 is made of epoxy resin, which is formed into a solid by a mold through a special process during the production process. It not only fixes the iron core coil 4 but also serves as the insulating material 3 and also presents the appearance of the product.

[0032] The tubular network 5 is made of non-magnetic metal and is placed on the inner wall of the product center hole 2. It is connected to the busbar passing through the middle through the equipotential line 6, so that there is no potential difference between the inner wall of the current transformer and the busbar, eliminating the discharge phenomenon of the intermediate air gap.

[0033] The annular net 7 is made of non-magnetic metal, placed on the end face or immersed in the end face shallowly, and combined with the tubular net 5 by soldering or wire. When charged, it has the same potential as the inner hole, which improves the electric field distribution on the end face, reduces the electric field gradient, and prevents flashover on the end face during the withstand voltage test.

[0034] The first shed 10 and the second shed 11 are provided to increase the surface creepage distance of the product and improve the insulation performance of the product when used in a dirty environment and high-altitude areas.

[0035] The connection terminal 12 is connected to the iron core coil 4 , and the outside can obtain the output signal of the iron core coil 4 by connecting the connection terminal 12 .

[0036] The above-mentioned embodiments only express the specific implementation methods of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the utility model. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model.

Claims

1. A through-type medium voltage current transformer, characterized in that: The invention comprises a shell (1) and a center hole (2) arranged on the inner side of the shell (1) along the axial direction of the shell (1), the shell (1) is filled with an insulating material (3), a plurality of iron core coils (4) are arranged in the shell (1), a tubular net (5) is arranged on the inner side wall of the center hole (2), an equipotential line (6) is connected to the tubular net (5), and the equipotential line (6) extends to the inner side of the center hole (2), and an annular net (7) is respectively arranged at both ends of the shell (1), and both annular nets (7) are connected to the tubular net (5).

2. A through-type medium voltage current transformer according to claim 1, characterized in that: The insulating material (3) is epoxy resin.

3. A through-type medium voltage current transformer according to claim 1 or 2, characterized in that: The iron core coil (4) is arranged in the insulating material (3) via a coil fixing member (8).

4. A through-type medium voltage current transformer according to claim 3, characterized in that: The coil fixing member (8) is made of non-magnetic metal.

5. A through-type medium voltage current transformer according to claim 4, characterized in that: A connecting flange (9) is provided at the middle portion of the outer side of the housing (1).

6. A through-type medium voltage current transformer according to claim 5, characterized in that: The connecting flange (9) is provided with a connecting terminal (12), and the connecting terminal (12) is connected to the iron core coil (4).

7. A through-type medium voltage current transformer according to claim 1, characterized in that: A first umbrella skirt (10) and a second umbrella skirt (11) are respectively provided on the outer side of the shell (1).

8. A through-type medium voltage current transformer according to claim 7, characterized in that: The first umbrella skirt (10) and the second umbrella skirt (11) are both in two groups and are respectively arranged on both sides of the connecting flange (9).

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