High-precision air core current transformer and integrated measurement and control protection device

Abstract

The utility model discloses a high-precision air core current transformer and integrated measurement and control protection device, which comprises an annular framework, even number layers of first enameled coils are uniformly and densely arranged on the annular framework, two adjacent layers of first enameled coils are symmetrically arranged and have the same number of turns, and the two adjacent layers of first enameled coils are oppositely arranged along the winding direction of the annular framework. The inner layer head end and the outer layer tail end of the first enameled coil are current signal output connecting ends, and the shielding layer is wound on the outer side of the first enameled coil on the outermost layer. The influence of the installation position change of a busbar or a cable penetrating through the annular structure of the air-core current transformer on the secondary mutual inductance output of the mutual inductance coil can be solved through the balance symmetry of the mutual inductance coil; and meanwhile, the mutual inductance output of the two layers of coils with the same number of turns and opposite winding directions also eliminates interference signals which are superposed on the two layers of coils by an external magnetic field or a magnetic field between phases of a three-phase circuit.

Description

Technical Field

[0001] The utility model relates to the field of relay protection, in particular to a high-precision air-core current transformer and an integrated measurement, control and protection device. Background Art

[0002] Current transformers are basic sensing electrical appliances in the field of electrical measurement and protection, with a wide range of demand and large quantities. There are many types of current transformers according to different usage locations and requirements. Among them, the Rogowski coil, also known as the air-core current transformer, is a type of current transformer that uses non-magnetic materials as the coil skeleton. Ring-shaped, circular, elliptical, rectangular, and other uniformly dense coils are often used. Corresponding to the primary loop current passing through the coil, based on the law of electromagnetic induction and Ampere's loop law, the coil induction output e(t) = -M[dit / dt], where M is the mutual inductance coefficient, that is, a voltage signal proportional to the primary loop current can be obtained by integration. Since the non-magnetic material used as the coil skeleton will not saturate, this type of coil has a large dynamic measurement current range and a high short-circuit current resistance capability. It has been widely used in the fields of medium and low voltage measurement, control, and protection. In particular, the densely packed coils processed with a circular skeleton have the best output stability. However, the processing requirements for air-core coils are relatively high. In addition to the requirements of the integral circuit design, the changes in the self-inductance and stray capacitance of the air-core coil itself have a significant impact on output accuracy. To achieve products with relatively stable performance and consistent repeatable processing parameters, the current production and processing of air-core transformers for power frequency applications mostly considers the use of materials with relatively small thermal deformation, such as PPS and PEI, for the bobbin. A circular ring structure is used whenever possible, and the coil winding process adopts a close-packed winding process as much as possible. For some products with higher requirements, the outer layer of the air-core coil is also added with an insulating layer and then a copper shielding layer is wrapped around it for grounding, further reducing various spatial stray interference. However, this also leads to complex production processes for air-core transformers, low production efficiency, and high overall production and processing costs. In particular, the processing efficiency of the additional shielding and grounding measures is even lower, making it difficult to meet the needs of large-scale production and supporting equipment.

[0003] At the same time, AC motors are the core electrical appliances for industrial automation drive and transmission, with a wide range of demand and large quantities. Various measurement, control and protection devices are used in their engineering applications. According to different usage sites and process operation requirements, there are many varieties and specifications of measurement, control and protection devices. In order to facilitate the production and maintenance of multiple varieties of products, different manufacturers currently use a modular structure in which the current transformer and the measurement, control and protection device body are designed and produced separately. This has led to quality risks such as disconnection of the connection between the transformer and the body, as well as the defect that the measurement accuracy deviation is large and is not suitable for motor energy consumption statistics due to the inability to perform pairing calibration. Utility Model Content

[0004] The technical problem solved by the utility model is to provide a high-precision air-core current transformer with better stability and measurement accuracy.

[0005] The technical solution adopted by the utility model to solve its technical problems is: a high-precision air-core current transformer, including an annular frame, on which an even number of first enameled coils are evenly and densely arranged, two adjacent layers of the first enameled coils are symmetrically wound and have the same number of turns, and the two adjacent layers of the first enameled coils are arranged in opposite directions along the winding direction of the annular frame, the inner head end and the outer tail end of the first enameled coil are current signal output connection terminals, and the utility model also includes a shielding layer wound around the outside of the outermost first enameled coil.

[0006] Furthermore, the enameled wires of two adjacent layers are connected end to end.

[0007] Furthermore, the shielding layer is a second enameled wire, and both ends of the second enameled wire are grounded ends.

[0008] The present invention also discloses an integrated measurement, control and protection device, including the high-precision air-core current transformer described above, including a bottom shell, wherein a partition is provided in the bottom shell, so that a current transformer installation cavity and a circuit board installation cavity are formed in the bottom shell, a main control board and a power relay board are sequentially arranged from top to bottom in the circuit board installation cavity, a first Phoenix terminal card interface and a second Phoenix terminal card interface are provided on a side plate of the bottom shell close to the circuit board installation cavity from top to bottom, a first Phoenix terminal card interface is clamped in the first Phoenix terminal card interface, a second Phoenix terminal is clamped in the second Phoenix terminal card interface, the main control board is connected to the first Phoenix terminal signal, and the power relay board is connected to the second Phoenix terminal signal;

[0009] Three air-core current transformers corresponding to three-phase current are arranged in the transformer installation cavity, and connecting terminals for connecting the air-core current transformers are arranged on the main control board, and the connecting ends of the air-core current transformers are wound on the connecting terminals.

[0010] Furthermore, a support block for supporting the power relay board and the main control board is provided in the circuit board installation cavity.

[0011] Furthermore, a ring cavity for positioning and passing three-phase cables is provided in the transformer installation cavity.

[0012] Furthermore, the invention also includes an upper cover arranged on the bottom shell.

[0013] The beneficial effects of the utility model are:

[0014] 1. In this structure, by evenly arranging an even number of layers of enameled wire on the annular frame, the influence of changes in the installation position of the busbar or cable passing through the annular structure of the air-core current transformer on the secondary mutual inductance output of the mutual inductance coil can be solved through the balance and symmetry of the mutual inductance coil. At the same time, the mutual inductance output of the two layers of coils with the same number of turns and opposite winding directions can also eliminate the interference signal superimposed on the two layers of coils by the external or three-phase circuit phase-to-phase magnetic field.

[0015] 2. This structure always adds a shielding layer outside the first enameled coil, that is, the second coil output grounding is used to replace the traditional shielding layer, thereby further improving the measurement accuracy of the air-core current transformer.

[0016] 3. This structure integrates the Rogowski air-core current transformer and the measurement, control and protection device into an integrated design, unifying the appearance and structure of products of 160A and below, thus meeting the requirements of various specifications and grades of AC motors.

[0017] 4. The output signal of the Rogowski air-core current transformer of this structure will not be saturated and distorted. In conjunction with the measurement, control and protection devices, it can achieve a measurement and protection range of more than 20 times the maximum rated current. It can collect the actual current during motor startup and short-circuit faults, making protection safer and more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a structural schematic diagram of a high-precision air-core current transformer according to an embodiment of the present application.

[0019] Figure 2 This is a schematic structural diagram of the integrated measurement, control and protection device of an embodiment of the present application.

[0020] Figure 3 This is a schematic diagram of the internal structure of the integrated measurement, control and protection device of an embodiment of the present application.

[0021] Figure 4 This is a cross-sectional view of the integrated measurement, control and protection device of an embodiment of the present application.

[0022] Marked in the figure are: air-core current transformer 1, annular skeleton 101, first enameled coil 102, shielding layer 103, bottom shell 2, partition 3, main control board 4, power relay board 5, first Phoenix terminal 6, second Phoenix terminal 7, connecting terminal 8, support block 9, positioning ring cavity 10, and upper cover 11. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0024] like Figure 1As shown, an embodiment of the present application discloses a high-precision air-core current transformer, comprising an annular skeleton 101, on which an even number of first enameled coils 102 are evenly and densely arranged, and two adjacent layers of the first enameled coils 102 are symmetrically wound and have the same number of turns, and the two adjacent layers of the first enameled coils 102 are arranged in opposite directions along the winding direction of the annular skeleton 101, the inner head end and the outer tail end of the first enameled coil 102 are current signal output connection terminals, and also includes a shielding layer 103 wound around the outside of the outermost first enameled coil 102.

[0025] Specifically, in this structure, a winding machine is used to perform winding operations on the annular skeleton 101, that is, when the annular winding equipment is processed, it is immediately returned to the dense winding process for one circle after it is densely wound in a counterclockwise or clockwise direction to the end, so as to achieve a completely symmetrical processing process in which the two layers of coils have the same number of turns and the annular winding directions are opposite. The air-core current transformer 1 processed in this way can solve the influence of the change in the installation position of the busbar or cable passing through the annular structure of the air-core current transformer 1 on the secondary mutual inductance output of the mutual inductance coil through the balanced symmetry of the mutual inductance coil. At the same time, the mutual inductance output of the two layers of coils with the same number of turns and opposite winding directions also eliminates the interference signal superimposed on the two layers of coils by the external or three-phase circuit phase-to-phase magnetic field. After the two layers of coils are processed and tapped by the annular winding equipment, another layer of coils can be densely wound. The lead of this layer of coils is directly used to replace the shielding grounding, effectively reducing the influence of various stray interferences in the space and improving the measurement accuracy of the air-core current transformer 1.

[0026] In this embodiment, the enameled wires of two adjacent layers are connected end to end.

[0027] The above-mentioned structure allows the annular winding equipment to perform winding operations on the annular skeleton 101 without the need for wire breaking in the middle. When performing the second layer of winding, only reverse winding is required, thereby increasing the production efficiency of this structure.

[0028] In this embodiment, the shielding layer 103 is a second enameled wire, and both ends of the second enameled wire are grounded.

[0029] In this structure, enameled wire is used as the shielding layer 103 structure. On the one hand, it can replace the existing shielding cover to play a shielding role, thereby further improving the measurement accuracy of the air-core current transformer. On the other hand, during the winding operation, the same winding equipment can be used, and during the winding operation, there is no need to change the wire operation, which makes the current transformer more convenient during production.

[0030] like Figures 2 to 4As shown, the present invention also discloses an integrated measurement, control and protection device, including the high-precision air-core current transformer described above, including a bottom shell 2, a partition 3 is provided in the bottom shell 2, so that a current transformer installation cavity and a circuit board installation cavity are formed in the bottom shell 2, and a main control board 4 and a power relay board 5 are arranged in the circuit board installation cavity from top to bottom. A first Phoenix terminal 6 card interface and a second Phoenix terminal 7 card interface are provided on the side plate of the bottom shell 2 close to the circuit board installation cavity from top to bottom, the first Phoenix terminal 6 card interface is clamped with the first Phoenix terminal 6, and the second Phoenix terminal 7 card interface is clamped with the second Phoenix terminal 7, the main control board 4 is connected to the first Phoenix terminal 6 signal, and the power relay board 5 is connected to the second Phoenix terminal 7 signal;

[0031] Three hollow-core current transformers 1 corresponding to three-phase current are arranged in the transformer installation cavity. The main control board 4 is provided with a connection terminal 8 for connecting the hollow-core current transformer. The connection end of the hollow-core current transformer 1 is wound on the connection terminal 8, and the output end of the shielding layer is connected through the terminal on the main control circuit board to achieve grounding.

[0032] Specifically, each circuit board module used on the main control board 4 and the power relay board 5 may use an existing circuit module.

[0033] In this structure, the power relay board 5 is provided with a switching power supply module and a multi-way relay, a three-phase power signal circuit, and an analog and communication module for signal and control signal output, three-phase voltage signal access, analog output, and communication transmission; the main control board 4 is provided with multiple switching inputs, a human-machine interface and a status indication; the air-core current transformer 1 is an air-core coil.

[0034] In this structure, the Rogowski air-core current transformer 1 is integrated with the measurement, control and protection device, unifying the external structure of products of 160A and below, thereby meeting the requirements of various specifications and grades of AC motors.

[0035] In this embodiment, a support block 9 for supporting the power relay board 5 and the main control board 4 is provided in the circuit board installation cavity.

[0036] Specifically, the arrangement of the support block 9 provides certain support to the power relay board 5 when it is installed in the circuit board installation cavity, thereby preventing the power relay from being deformed due to being suspended in the air.

[0037] In this embodiment, a ring cavity 10 for positioning and passing three-phase cables is provided in the transformer installation cavity.

[0038] Specifically, when the air-core current transformer 1 is installed in the transformer installation cavity, the air-core current transformer 1 can be installed and positioned in the positioning ring cavity 10, that is, the positioning ring cavity 10 can, on the one hand, play a positioning role for the air-core current transformer 1 to prevent the air-core current transformer 1 from shaking, and on the other hand, it can also play a protective role for the air-core current transformer 1.

[0039] In this embodiment, an upper cover 11 is further included and is arranged on the bottom shell 2 .

[0040] In this structure, the upper cover 11 can protect the internal structures of the transformer installation cavity and the circuit board installation cavity, and prevent external structures such as dust from affecting the air-core current transformer 1 or the circuit board.

[0041] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-precision air-core current transformer, characterized by: The invention comprises an annular skeleton (101), on which an even number of first enameled coils (102) are evenly and closely wound. Two adjacent layers of the first enameled coils (102) are symmetrically wound and have the same number of turns. The two adjacent layers of the first enameled coils (102) are arranged in opposite directions along the winding direction of the annular skeleton (101). The inner head end and the outer tail end of the first enameled coils (102) serve as current signal output connection terminals. The invention also comprises a shielding layer (103) wound around the outer side of the outermost first enameled coil (102).

2. The high-precision air-core current transformer according to claim 1, characterized in that: The enameled wires of two adjacent layers are connected end to end.

3. The high-precision air-core current transformer according to claim 1, characterized in that: The shielding layer (103) is a second enameled wire, and both ends of the second enameled wire are grounded ends.

4. An integrated measurement, control and protection device, comprising the high-precision air-core current transformer according to any one of claims 1 to 3, characterized in that: The invention comprises a bottom shell (2), wherein a partition (3) is provided in the bottom shell (2), so that a current transformer installation cavity and a circuit board installation cavity are formed in the bottom shell (2), a main control board (4) and a power supply relay board (5) are sequentially provided in the circuit board installation cavity from top to bottom, a first Phoenix terminal (6) card interface and a second Phoenix terminal (7) card interface are provided on a side plate of the bottom shell (2) close to the circuit board installation cavity from top to bottom, a first Phoenix terminal (6) card interface is carded in the first Phoenix terminal (6), a second Phoenix terminal (7) card interface is carded in the second Phoenix terminal (7), the main control board (4) is signal-connected to the first Phoenix terminal (6), and the power supply relay board (5) is signal-connected to the second Phoenix terminal (7); Three air-core current transformers (1) corresponding to three-phase currents are arranged in the transformer installation cavity, and connection terminals (8) for connecting the air-core current transformers are arranged on the main control board (4), and the connection ends of the air-core current transformers (1) are wound around the connection terminals (8).

5. The integrated measurement, control and protection device according to claim 4, characterized in that: A support block (9) for supporting the power relay board (5) and the main control board (4) is provided in the circuit board installation cavity.

6. The integrated measurement, control and protection device according to claim 4, characterized in that: A ring cavity (10) for positioning and for passing a three-phase cable is provided in the mutual inductor installation cavity.

7. The integrated measurement, control and protection device according to claim 4, characterized in that: It also includes an upper cover (11) arranged on the bottom shell (2).

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