Combined current transformer module with zero sequence CT

Abstract

The utility model discloses a combined current transformer module with a zero sequence CT, which comprises a shell, a three-phase current transformer and a zero sequence current transformer, and the three-phase current transformer and the zero sequence current transformer form a transformer group with parallel axes and are arranged in the shell. A circuit board connected with a secondary output signal line of the mutual inductor group is arranged in the shell, a wiring terminal extending out of the shell is arranged on the circuit board, threading holes are formed in the two opposite sides of the shell, and the axes of the threading holes are parallel to the axis of the mutual inductor group; the three-phase current transformer and the zero-sequence current transformer are combined into a whole, the size specification, the wire outlet aperture, the transformation ratio parameter and the like all meet the actual requirements of the photovoltaic micro circuit breaker, and meanwhile the three-phase current and zero-sequence current conversion capacity is achieved, and the photovoltaic micro circuit breaker has the advantages of being simple in structure, small in size and convenient to install.

Description

Technical Field

[0001] The utility model relates to the technical field of electric quantity measurement, in particular to a combined current transformer module with a zero-sequence CT. Background Art

[0002] Current transformer is an important component for current detection in the electrical field. It can convert large load current into a small current that can be used for collection, facilitating the measurement and calculation of electrical quantity.

[0003] At present, the load current measurement of photovoltaic micro-breakers mainly adopts three-way split open CT, and then the vector data of the three-phase current is combined and calculated to obtain the zero-sequence current; however, although the split open CT used is easy to install, it is large in size, high in cost, low in precision, and has messy wiring. In particular, the zero-sequence current synthesized by vector is easily affected by harmonics and three-phase imbalance, resulting in large errors and frequent malfunctions of the switch. Utility Model Content

[0004] The technical problem to be solved by the utility model is that when the existing three-way split open CT is used to measure the load current of the photovoltaic micro-breaker, the volume is large, the cost is high and the accuracy is low.

[0005] In order to solve the above technical problems, the utility model provides a technical solution: a combined current transformer module with a zero-sequence CT, comprising a shell, a three-phase current transformer and a zero-sequence current transformer, characterized in that: the three-phase current transformer and the zero-sequence current transformer form a transformer group with axes parallel to each other and are arranged in the shell, a circuit board connected to the secondary output signal line of the transformer group is arranged in the shell, the circuit board is provided with wiring terminals extending out of the shell, and wire holes are provided on opposite sides of the shell, and the axes of the wire holes are parallel to the axis of the transformer group.

[0006] Furthermore, the three three-phase current transformers are arranged on the circuit board in a front-to-back staggered manner.

[0007] Furthermore, the housing includes an L-shaped left housing and a right housing, the left housing and the right housing are buckled together to form a chamber for storing the mutual inductor group and the circuit board, and are connected and fixed by bolts.

[0008] Furthermore, a groove is provided on one side of either the left shell or the right shell, and forms a lead hole for the connecting terminal to extend out with a side of the other shell.

[0009] The beneficial effects of the utility model are:

[0010] 1. This application combines a three-phase current transformer and a zero-sequence current transformer into one. The size specifications, lead-out line aperture, transformation ratio parameters, etc. all meet the actual needs of photovoltaic micro-breakers. At the same time, it has the ability to convert three-phase current and zero-sequence current, and has the characteristics of simple structure, small size, and easy installation.

[0011] 2. The present application is small in size and can be placed directly inside a narrow photovoltaic grid-connected box. Because of its simple manufacturing process, the cost is significantly lower than that of an open CT, especially for the zero-sequence current transformer. Compared with the vector synthesis method, the use of an independent CT can improve the anti-interference ability and stability, and the accuracy is significantly improved. At the same time, the rated transformation ratio of the three-phase current transformer and the zero-sequence current transformer can be selected according to actual conditions to meet actual needs.

[0012] 3. In this application, the secondary output signals of the three-phase current transformer and the zero-sequence current transformer are led out through the wiring terminals on the PCB circuit board. The output signals are transmitted using flat cables. The wiring is simple and neat, and there will be no phenomenon of split CT signal lines being randomly coiled.

[0013] In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the description of the embodiments are briefly introduced below. Obviously, the drawings described below are only two of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0015] Figure 1 This is a schematic diagram of the structure of this application.

[0016] Figure 2 This is the wiring diagram after implementation of this application.

[0017] In the figure, 1-three-phase current transformer, 2-zero-sequence current transformer, 3-circuit board, 4-connection terminal, 5-threading hole, 6-left housing, 7-right housing, 8-groove, 9-bolt;

[0018] A-photovoltaic micro-breaker, B-cable, C-signal line. DETAILED DESCRIPTION

[0019] The embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as being limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0020] It should be understood that the various steps described in the method implementation of the present utility model can be performed in different orders and / or performed in parallel. In addition, the method implementation may include additional steps and / or omit the steps shown. The scope of the present utility model is not limited in this respect.

[0021] The names of the messages or information exchanged between multiple devices in the implementation manner of the present utility model are only used for illustrative purposes, and are not used to limit the scope of these messages or information. Embodiment 1

[0022] like Figure 1-2 As shown, a combined photovoltaic micro-breaker A current transformer module with a zero-sequence CT includes a shell, a three-phase current transformer 1 and a zero-sequence current transformer 2. The three-phase current transformer 1 and the zero-sequence current transformer 2 form a transformer group with axes parallel to each other and are arranged in the shell. The three-phase current is measured by three three-phase current transformers 1, and the zero-sequence current is measured by an independent CT to improve the anti-interference ability and stability, and the accuracy is significantly improved; a circuit board 3 connected to the secondary output signal line C of the transformer group is arranged in the shell, and the three three-phase current transformers 1 are arranged on the circuit board 3 in a front-to-back staggered manner. The circuit board 3 is provided with a wiring terminal 4 extending out of the shell, and the secondary output signals of the three-phase current transformer 1 and the zero-sequence current transformer 2 are both led out through the wiring terminal 4 on the pcb circuit board 3. The output signal is transmitted using a wiring arrangement, and the wiring is simple and neat. The split CT signal line C will not be randomly coiled. Wire holes 5 are provided on opposite sides of the shell to facilitate the cable B to pass through this application. Embodiment 2

[0023] like Figure 1-Figure 2 As shown, this embodiment is obtained by further describing the technical features such as the shell on the basis of the first embodiment. The remaining technical features are the same as those of the first embodiment, and the similarities are not repeated here. The difference between this embodiment and the first embodiment is that: the shell includes an L-shaped left shell 6 and a right shell 7, the left shell 6 and the right shell 7 are interlocked to form a chamber for storing the mutual inductor group and the circuit board 3, and are connected and fixed by bolts 9; a groove 8 is provided on one side of either the left shell 6 or the right shell 7, and a lead hole for the terminal 4 to extend is formed with the other side.

[0024] In this embodiment, the shell includes an L-shaped left shell 6 and a right shell 7, so that the chamber opening is larger, which is convenient for the installation of the three-phase current transformer 1, the zero-sequence current transformer 2 and the circuit board 3 (by snapping and pressing the left shell 6 and the right shell 7 together), and the lead hole is a groove 8 set on one side of either the left shell 6 or the right shell 7, which is convenient and simple to manufacture.

[0025] When used after assembly, the present application is placed under the photovoltaic micro-breaker switch A, the wire hole 5 is aligned with the switch terminal of the photovoltaic micro-breaker switch A, and the primary cable B is connected to the switch terminal through the wire hole 5; the output signal of the transformer group is led out from the terminal row formed by the wiring terminals 4 on the circuit board 3 and connected to the external signal line C, where the terminal row sequence is: Ia+ Ia-Ib+ Ib- Ic+ Ic- I0+ I0-.

[0026] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A combined current transformer module with a zero-sequence CT, comprising a housing, a three-phase current transformer and a zero-sequence current transformer, characterized in that: The three-phase current transformer and the zero-sequence current transformer form a transformer group with axes parallel to each other and are arranged in the shell. A circuit board connected to the secondary output signal line of the transformer group is arranged in the shell. The circuit board is provided with wiring terminals extending out of the shell. Wire holes are provided on opposite sides of the shell, and the axes of the wire holes are parallel to the axis of the transformer group.

2. The combined current transformer module with zero-sequence CT according to claim 1 is characterized in that: The three three-phase current transformers are arranged on the circuit board in a front-to-back staggered manner.

3. The combined current transformer module with zero-sequence CT according to claim 2 is characterized in that: The housing comprises an L-shaped left housing and a right housing, the left housing and the right housing are buckled together to form a chamber for storing the mutual inductor group and the circuit board, and are connected and fixed by bolts.

4. The combined current transformer module with zero-sequence CT according to claim 3 is characterized in that: A groove is arranged on one side of either the left shell or the right shell, and a lead hole for the connecting terminal to extend is formed with one side of the other shell.

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