Totally-enclosed current transformer

Abstract

The utility model belongs to the technical field of transformers, and particularly relates to a totally-enclosed current transformer, which comprises an insulating shell, a protection iron core, a metering iron core, a secondary protection winding and a secondary metering winding, the insulating shell comprises a shell body, an annular base body protruding out of the shell body and an umbrella skirt arranged on the side portion of the shell body. The shell is provided with a circular through hole for a current-carrying conductor to pass through, the shell is provided with a rectangular fixing groove which is sunken towards the interior of the insulating shell at the position of the circular through hole, the circular through hole extends to the groove bottom of the rectangular fixing groove along the axis direction of the circular through hole, and the annular seat body and the circular through hole are coaxially arranged; the axis of the umbrella skirt is perpendicular to the axis of the circular through hole, a wiring board is arranged in the umbrella skirt, and wire inlet terminals and wire outlet terminals of the secondary protection winding and the secondary metering winding are connected to the wiring board. The device can realize protection and metering functions at the same time, and is convenient to install.

Description

Technical Field

[0001] The utility model belongs to the technical field of mutual inductors, and in particular relates to a fully enclosed current mutual inductor. Background Art

[0002] The current transformer is an instrument that converts the large current on the primary side into a small current on the secondary side for measurement based on the principle of electromagnetic induction. The current transformer is composed of a closed iron core and windings. Its primary winding has few turns and is connected in series in the circuit of the current to be measured, so it often has the entire current of the circuit flowing through it. The secondary winding has more turns and is connected in series in the measuring instrument and the protection circuit. When the current transformer is working, its secondary circuit is always closed, so the impedance of the series coil of the measuring instrument and the protection circuit is very small, and the working state of the current transformer is close to short circuit.

[0003] In the measurement and protection of power systems, current transformers can be used with measuring instruments to measure the current and electric energy of the system, and with relays to protect the system and equipment from overcurrent, overload and grounding. The use of current transformers must meet both the requirements of protection and measurement and the requirements of accuracy. Especially for high voltage and small ratio current transformers, they must meet the above requirements while maintaining product stability.

[0004] Most of the existing current transformers usually only have a measurement function or only have a protection function. For a high-voltage switch cabinet equipped with a measuring instrument and a protection device, at least two current transformers need to be installed to connect with the measuring instrument and the protection device respectively, which undoubtedly increases the number of current transformers used and increases the cost. In addition, the existing current transformers are usually installed by fixing the mounting plate on the current transformer to the corresponding structure in the cabinet with fasteners such as bolts and nuts. This installation method is relatively cumbersome. Utility Model Content

[0005] The purpose of the utility model is to overcome the deficiencies of the prior art and provide a fully enclosed current transformer.

[0006] In order to solve the above problems, the fully enclosed current transformer provided by the utility model adopts the following technical solutions:

[0007] A fully enclosed current transformer comprises an insulating shell and a protective iron core, a metering iron core, a secondary protective winding and a secondary metering winding cast inside the insulating shell, wherein the secondary protective winding is wound on the protective iron core and the secondary metering winding is wound on the metering iron core;

[0008] The insulating shell comprises a shell, an annular seat protruding out of the shell, and an umbrella skirt arranged on the side of the shell;

[0009] The shell is provided with a circular through hole for the current-carrying conductor to pass through, and the shell is provided with a rectangular fixing groove recessed toward the inside of the insulating shell at the position of the circular through hole, the circular through hole extends along its axial direction to the bottom of the rectangular fixing groove, and the annular seat is coaxially arranged with the circular through hole;

[0010] The axis of the umbrella skirt is perpendicular to the axis of the circular perforation. A wiring board is arranged inside the umbrella skirt. The incoming and outgoing terminals of the secondary protection winding and the secondary metering winding are connected to the wiring board.

[0011] Furthermore, the shell is an annular column structure, and the axis of the shell is the same as the axis of the circular through hole.

[0012] Furthermore, the shed is arranged at the center position of the axial direction of the shell, the axis of the wiring board is the same as the axis of the shed, and the incoming and outgoing terminals of the secondary protection winding and the secondary metering winding are arranged in a rectangular array on the wiring board.

[0013] Furthermore, the insulating shell is integrally cast by epoxy resin.

[0014] Furthermore, the lengths of the groove walls of the rectangular fixing groove are the same.

[0015] Furthermore, the four vertices of the rectangular fixing groove are in contact with the inner wall of the annular seat body.

[0016] The beneficial effects of the fully enclosed current transformer of the utility model are:

[0017] The fully enclosed current transformer of the utility model is provided with a secondary protection winding and a secondary metering winding at the same time, and can be connected to a measuring device and a protection device at the same time, outputting a protection current and a metering current. It can be applied in a high-voltage switch cabinet to reduce the number of current transformers used. In addition, through integral casting of epoxy resin, a fully enclosed structure is formed, the overall insulation performance is good, an umbrella skirt is provided, the creepage distance is large, and maintenance is convenient. Compared with the existing current transformers, the utility model does not provide a corresponding connection fixing plate structure on the insulating shell of the current transformer, but instead uses the inner cavity formed by the rectangular fixing groove and the annular seat body to be clamped and fixed with the corresponding structure in the switch cabinet, thereby reducing the use of components such as bolts and nuts, and making installation more convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By reading the detailed description below with reference to the accompanying drawings, the above and other purposes, features and advantages of the exemplary embodiments of the present invention will become easy to understand. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0019] Figure 1It is a front view of the fully enclosed current transformer of the utility model;

[0020] Figure 2 A top view of a fully enclosed current transformer of the utility model;

[0021] Figure 3 The utility model is a schematic diagram of the installation between the protection iron core, the metering iron core, the secondary protection winding and the secondary metering winding in the fully enclosed current transformer.

[0022] Description of reference numerals:

[0023] 1. Insulating shell; 2. Shell; 3. Annular seat; 4. Umbrella skirt; 5. Terminal block; 6. Protective iron core; 7. Circular perforation; 8. Rectangular fixing groove; 9. Protective winding incoming terminal; 10. Protective winding outgoing terminal; 11. Metering winding incoming terminal; 12. Metering winding outgoing terminal; 13. Insulating layer; 14. Metering iron core; 15. Secondary protection winding; 16. Secondary metering winding. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0025] The principle and spirit of the present invention are explained in detail below with reference to several representative embodiments of the present invention.

[0026] Embodiment 1 of the fully enclosed current transformer provided by the utility model:

[0027] like Figure 1 , Figure 2 and Figure 3 As shown, the fully enclosed current transformer includes an insulating casing 1 and a protective iron core 6, a metering iron core 14, a secondary protective winding 15 and a secondary metering winding 16 cast inside the insulating casing 1, the secondary protective winding 15 is wound on the protective iron core 6, the secondary metering winding 16 is wound on the metering iron core 14, and the secondary protective winding 15 and the secondary metering winding 16 are both covered with an insulating layer 13, and the insulating layer 13 includes insulating cardboard, a gasket and corrugated paper.

[0028] In this embodiment, the insulating housing 1 is integrally cast by epoxy resin to form a fully enclosed structure. The insulating housing 1 includes a housing 2, an annular seat 3 protruding from the housing 2, and an umbrella skirt 4 arranged on the side of the housing 2, wherein the housing 2 is an annular cylindrical structure, and a coaxial circular perforation 7 is provided on the housing 2, and the circular perforation 7 can allow the current-carrying conductor to pass through. A rectangular fixing groove 8 recessed toward the inside of the housing 2 is provided on the housing 2 at the position of the circular perforation 7, and the rectangular fixing groove 8 has a certain depth, and the end of the circular perforation 7 extends along the axis of the housing 2 to the bottom of the rectangular fixing groove 8. The annular seat 3 and the rectangular fixing groove 8 are located on the same axial side of the housing 2, and the annular seat 3 is coaxially arranged with the housing 2. The rectangular fixing groove 8 and the circular perforation 7 are both located inside the annular seat 3, and the lengths of the groove walls of the rectangular fixing groove 8 are the same, and there is a certain distance between the four vertices of the rectangular fixing groove 8 and the inner wall of the annular seat 3.

[0029] The umbrella skirt 4 is arranged on the side of the shell 2, and is arranged on the opposite side of the annular seat body 3. The axis of the umbrella skirt 4 is perpendicular to the axis of the circular through hole 7, which can increase the creepage distance. In order to ensure the stability of the overall structure, the umbrella skirt 4 is arranged at the center position of the axis direction of the shell 2, which is a symmetrical structure. There is a cavity in the umbrella skirt 4, and a circular terminal block 5 is installed in the cavity. The axis of the terminal block 5 is the same as the axis of the umbrella skirt 4. The protection winding incoming terminal 9 and the protection winding outgoing terminal 10 of the secondary protection winding 15 and the metering winding incoming terminal 11 and the metering winding outgoing terminal 12 of the secondary metering winding 16 are all connected to the terminal block 5 through the above-mentioned cavity, and the four terminals are arranged in a rectangular array on the terminal block 5.

[0030] In actual use, the protection winding inlet terminal 9 and the protection winding outlet terminal 10 are connected to the protection device, and the metering winding inlet terminal 11 and the metering winding outlet terminal 12 are connected to the metering device. During installation, the current transformer is clamped on the corresponding structure in the switch cabinet through the rectangular fixing groove 8 and the annular seat body 3 to achieve rapid installation of the current transformer.

[0031] The fully enclosed current transformer of the utility model has excellent insulation and mechanical properties, small overall size, light weight, large creepage distance, and easy maintenance. It can be used for current and electric energy measurement and relay protection in power systems with a voltage of 10kv and below, and can output 5A protection current and 1A metering current with accurate metering accuracy and stable performance.

[0032] Embodiment 2 of the fully enclosed current transformer provided by the utility model:

[0033] The main difference between this embodiment and the first embodiment is that in the first embodiment, there is a certain distance between the four vertices of the rectangular fixing groove and the inner wall of the annular seat body. In this embodiment, the four vertices of the rectangular fixing groove are in contact with the inner wall of the annular seat body, making the structure of the current transformer more compact and smaller in size.

[0034] Embodiment 3 of the fully enclosed current transformer provided by the utility model:

[0035] The main difference between this embodiment and the first embodiment is that in the first embodiment, the housing is an annular column structure. In this embodiment, the housing is a rectangular parallelepiped structure.

Claims

1. A fully enclosed current transformer, characterized in that: It includes an insulating shell and a protective iron core, a metering iron core, a secondary protective winding and a secondary metering winding cast inside the insulating shell, wherein the secondary protective winding is wound on the protective iron core, and the secondary metering winding is wound on the metering iron core; The insulating housing comprises a housing, an annular seat protruding from the housing, and an umbrella skirt arranged on the side of the housing; the housing is provided with a circular through hole for the current-carrying conductor to pass through, and the housing is provided with a rectangular fixing groove recessed toward the inside of the insulating housing at the position of the circular through hole, the circular through hole extends along its axial direction to the bottom of the rectangular fixing groove, and the annular seat is coaxially arranged with the circular through hole; The axis of the umbrella skirt is perpendicular to the axis of the circular perforation. A wiring board is arranged inside the umbrella skirt. The incoming and outgoing terminals of the secondary protection winding and the secondary metering winding are connected to the wiring board.

2. The fully enclosed current transformer according to claim 1, characterized in that: The shell is an annular column structure, and the axis of the shell is the same as the axis of the circular through hole.

3. The fully enclosed current transformer according to claim 2, characterized in that: The shed is arranged at the center of the shell in the axial direction, the axis of the wiring board is the same as that of the shed, and the incoming and outgoing terminals of the secondary protection winding and the secondary metering winding are arranged in a rectangular array on the wiring board.

4. The fully enclosed current transformer according to any one of claims 1 to 3, characterized in that: The insulating shell is integrally cast by epoxy resin.

5. The fully enclosed current transformer according to any one of claims 1 to 3, characterized in that: The lengths of the groove walls of the rectangular fixing groove are all the same.

6. The fully enclosed current transformer according to claim 1, characterized in that: The four vertices of the rectangular fixing groove are in contact with the inner wall of the annular seat body.

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