Sleeve through Rogowski coil current mutual sensor

Abstract

The invention relates to the technical field of sensors, and discloses a sleeve straight-through Rogowski coil current mutual sensor, which comprises a high-inductance framework, a winding, a composite shielding layer, an epoxy resin insulating castable, a sleeve secondary signal element, a fixing bolt, a combined secondary signal output cable and a sensor outer shell, wherein the winding comprises a coil which is uniformly wound on the high-inductance framework, the tail end of the coil is connected with a return turn to form a closed loop, the composite shielding layer is composed of a stainless steel shielding cover and a copper foil coated on the coil, the measurement range is wide, the precision is higher, the saturation is avoided, the anti-interference capability is strong, the broadband response is realized, the noise is low, the transmission signal is stable, and the size is small. The current sensor saves space, is convenient to install, and is more suitable for the field of intelligent power grid upgrading and high-voltage equipment monitoring.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, in particular to a bushing through type Rogowski coil current transformer suitable for ring main unit power distribution network, smart grid and traveling wave positioning system; in particular to a bushing through type Rogowski coil current transformer, which combines wide frequency response, self-integration characteristics and composite shielding technology, and can be widely applied to the fields of current measurement, fault protection and high-precision insulation monitoring. BACKGROUND

[0002] With the rapid development of China's economic construction, the demand for electricity is increasing, and the power distribution system in China is developing towards large capacity and super high voltage. Correspondingly, the development of electrical equipment in this direction has become an inevitable trend. As an important device for measuring line and equipment current signals, electronic current sensors will inevitably have a large demand. With the development of power distribution networks, the development trend of intelligence, integration and miniaturization, the traditional electromagnetic transformer has the disadvantages of large size, heavy weight, easy saturation and poor linearity, which cannot meet the requirements of new intelligent power systems. SUMMARY

[0003] The purpose of the present application is to solve the above problems, and a bushing through type Rogowski coil current transformer is designed to complete the important technical problems of intelligence, systematization, integration and miniaturization. Modern low-power coil sensing technology and non-contact measurement technology based on Faraday's law of electromagnetic induction, high-inductance skeleton coil self-integration technology, wide frequency response technology, and power metering technology are used to form a device that converts large current signals into small analog signals through sensing.

[0004] The present application provides a bushing through type Rogowski coil current transformer, which comprises a high inductance skeleton, a winding, a composite shielding layer, an epoxy resin insulation casting material, a bushing secondary signal element, a fixing bolt, a combined secondary signal output cable and a sensor shell, wherein the winding comprises a coil uniformly wound on the high inductance skeleton, the coil end is connected to the return turn to form a closed loop, and the composite shielding layer is composed of a stainless steel shielding cover and a copper foil wrapped on the coil.

[0005] Optionally, in the first implementation manner of the present application, the entire coil of the winding is uniformly wound on a ring-shaped non-magnetic high inductance skeleton, and a current-carrying conductor carrying the measured current is arranged in the ring-shaped non-magnetic high inductance skeleton of the air core coil and parallel to the axis of the ring-shaped non-magnetic high inductance skeleton.

[0006] Optionally, in the second implementation manner of the present application, for a sinusoidal current in a steady state, the output voltage of the air core coil can be expressed as: e=M·jω·I Wherein, I represents the measured current, M represents mutual inductance coefficient, omega represents the angular frequency of sinusoidal current, and e represents the output voltage of the air core coil.

[0007] Optionally, in the third implementation mode of the present application, the coil on the high inductance skeleton generates an inductance self-integration function to convert the signal into a secondary signal.

[0008] Optionally, in the fourth implementation mode of the present application, the sensor housing is embedded with a high inductance skeleton, a winding, an epoxy resin insulation casting material, a bushing secondary signal element, and a combined secondary signal output cable.

[0009] Optionally, in the fifth implementation mode of the present application, the current-carrying wire flowing with the measured current is placed behind the high inductance skeleton, the bushing secondary signal element is installed at the secondary output end, and the combined secondary signal output cable is welded, and the epoxy resin insulation casting material is cast in the sensor housing.

[0010] Optionally, in the sixth implementation mode of the present application, the sensor generates a proportional current signal through the high inductance skeleton, the winding, and the epoxy resin insulation casting material, and converts and outputs an analog voltage signal through the bushing secondary signal element, and finally outputs the signal to the customer end for metering through the combined secondary signal output cable.

[0011] Optionally, in the seventh implementation mode of the present application, the bushing secondary signal element of the sensor uses a twisted shielded wire to shield the corresponding pins of the combined secondary signal output cable.

[0012] Optionally, in the eighth implementation mode of the present application, the fixing bolt is arranged at the bottom of the sensor.

[0013] Optionally, in the ninth implementation mode of the present application, the lower end of the sensor is provided with a sealing ring, and the sealing ring is combined with the combined secondary signal output cable to realize sealing and limiting.

[0014] The bushing through type Rogowski coil current mutual sensor provided by the present application has a wide measurement range, higher precision, no saturation, strong anti-interference ability, wide frequency response, low noise, stable transmission signal, small size, space saving, convenient installation, and is more suitable for current sensors in the fields of smart grid upgrading and high-voltage equipment monitoring. BRIEF DESCRIPTION OF DRAWINGS

[0015] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments with reference made to the accompanying drawings. The drawings are for purposes of illustration only and are not intended to be limiting of the application.

[0016] Figure 1 A circuit schematic diagram of a bushing through-type Rogowski coil current sensor is provided for an embodiment of the present application, wherein Figure 1 (a) is a structural schematic diagram of the sensor, Figure 1 (b) is an equivalent circuit model of the sensor; Figure 2 A perspective view of a bushing through-type Rogowski coil current sensor is provided for an embodiment of the present application; Figure 3 An internal component assembly diagram of a bushing through-type Rogowski coil current sensor is provided for an embodiment of the present application; Figure 4 An assembly diagram of a bushing through-type Rogowski coil current sensor and a split-type combined sensor that acts on the bushing is provided for an embodiment of the present application; Figure 3 Reference numerals: 1, high inductance skeleton; 2, winding; 3, composite shielding layer; 4, epoxy resin insulation casting material; 5, bushing secondary signal element; 6, fixing bolt; 7, combined secondary signal output cable; 8, sensor housing. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present application.

[0018] Please refer to Figures 1-4 The present embodiment provides a bushing through-type Rogowski coil current sensor, which comprises a high inductance skeleton 1, a winding 2, a composite shielding layer 3, an epoxy resin insulation casting material 4, a bushing secondary signal element 5, a fixing bolt 6, a combined secondary signal output cable 7, and a sensor housing 8. The winding comprises a coil uniformly wound on the high inductance skeleton, and the coil is connected to a return turn at the end to form a closed loop. The composite shielding layer is composed of a stainless steel shielding cover and a copper foil wrapped on the coil.

[0019] In Figure 1 , the present embodiment provides a bushing through-type Rogowski coil current sensor, which comprises a high inductance skeleton 1, a winding 2, a composite shielding layer 3, an epoxy resin insulation casting material 4, a bushing secondary signal element 5, a fixing bolt 6, a combined secondary signal output cable 7, and a sensor housing 8. The winding comprises a coil uniformly wound on the high inductance skeleton, and the coil is connected to a return turn at the end to form a closed loop. The composite shielding layer is composed of a stainless steel shielding cover and a copper foil wrapped on the coil. Figure 1(a) is a structural diagram of the sensor: a conductor passes through a hollow coil, the coil is supported by a high inductance skeleton, the winding is uniformly wound and forms a closed loop, the end is connected through a return turn to reduce electromagnetic interference, when current flows in the conductor, a magnetic field B is generated around it, which is coupled into the coil, according to Faraday's law of electromagnetic induction, a voltage output Vout proportional to the rate of change of current is induced at both ends of the coil; Figure 1 (b) is an equivalent circuit model of the sensor: the magnetic flux generated by the primary current ip is induced to the secondary side through mutual inductance M, the secondary loop includes the inductance Ls, resistance Rs and parasitic capacitance Cs of the coil, the load is high impedance burden RB, the induced electromotive force E is proportional to the rate of change of the primary current, and the output voltage Us reflects the dynamic change of the measured current.

[0020] In Figure 2 , the ring structure is used to pass through the primary conductor to realize non-contact current measurement, the sensor internally includes a high inductance skeleton, a uniformly wound winding and a composite shielding layer composed of a stainless steel shielding cover and a copper foil, which effectively suppresses electromagnetic interference and improves signal stability, the entire device is sealed and insulated by epoxy resin insulation casting material to ensure safe operation in harsh environments such as high pressure and high humidity, a combined secondary signal output cable is led out from the bottom of the sensor, the end is connected to an RJ45 interface, which is convenient for docking with external monitoring systems or data acquisition equipment, the terminal pin positions of the RJ45 connector are marked in the figure: S1 / PIN1 and S2 / PIN2 are signal output terminals, a / PIN7 and b / PIN8 are ground or auxiliary signal terminals, indicating that the sensor supports differential signal output, improves anti-interference ability, and the overall design is compact and easy to install.

[0021] In this embodiment, the transformer body and the secondary signal RJ45 shielded output cable are designed with anti-interference shielding function, among which the CAT6 standard RJ45 shielded output cable line reduces the influence of EMI, maintains data integrity and improves high-speed performance.

[0022] In this embodiment, the Rogowski Coil is a hollow ring coil, and its output signal is caused by the change of the alternating magnetic field generated by the measured current. According to Faraday's law of electromagnetic induction: ; Among them, represents the induced voltage at the output end of the coil, represents the mutual inductance coefficient between the coil and the measured conductor, represents the rate of change of the measured current with time.

[0023] In the embodiment, the sleeve through core type Rogowski coil current sensor is uniformly wound on a ring-shaped non-magnetic high inductance skeleton, the current-carrying wire flowing with the measured current is placed in the ring-shaped non-magnetic high inductance skeleton of the air core coil and is parallel to the axis of the ring-shaped non-magnetic high inductance skeleton, and for a steady-state sinusoidal current, the output voltage of the air core coil can be represented as: e = M j omega I; Wherein, I represents the measured current, M represents the mutual inductance coefficient, omega represents the angular frequency of the sinusoidal current, and e represents the output voltage of the air core coil.

[0024] In the embodiment, in the current sensor, the high inductance skeleton of the current sensor is placed in the shielding shell, the bidirectional transient suppression diode plays a role of overcurrent protection, the skeleton coil generates an inductance self-integration function to convert the signal into a secondary signal, and the self-integration function is realized.

[0025] In the embodiment, a sleeve through core type main body is provided, which directly acts on the high voltage sleeve ground end or the outside of the bus cylinder; wherein the coil is uniformly wound on a high inductance skeleton, and the end is connected to a return turn to form a closed loop, and the magnetic field coupling efficiency of the coil is improved; wherein the composite shielding layer adopts a stainless steel shielding cover and a copper foil coating of the coil to form a kind of electrostatic shielding and electromagnetic shielding function, reducing external interference and position sensitivity error.

[0026] In the embodiment, a sleeve through core type main body is provided, which directly acts in the sleeve, and the effect of non-contact sleeve is achieved; two bolts are reserved at the bottom of the sensor body lower end for actual installation environment installation and fixation, and the position fixation also avoids the influence of position error on the sensor.

[0027] In the embodiment, the enameled wire is uniformly wound on the high inductance skeleton; through the new type of multi-layer winding process, the coil is uniformly arranged on the high inductance skeleton, wherein the end forms a closed loop through the return turn to enhance the magnetic field coupling efficiency; the high number of turns multi-layer winding design improves the inductance of the coil and supports the self-integration function; wherein the air core coil avoids the core hysteresis loss and supports the measurement of transient current above 50kA, and realizes the monitoring of the power system in the high voltage, high frequency and complex electromagnetic environment.

[0028] In the embodiment, the plastic shell is embedded with the secondary winding of the sensor and the sleeve secondary signal element part, the so-called secondary winding is designed and wound by high-quality high inductance skeleton and multi-turn enameled wire, and is filled with epoxy resin insulating material, the sleeve through core type Rogowski coil current sensor passes through the secondary winding after the primary winding, and the corresponding proportional current signal is inducted, and the analog voltage small signal is converted and output through the secondary signal conversion unit, and finally the output signal is output to the client for metering, protection and collection.

[0029] In this embodiment, the secondary output cable outputs signals to the client for metering use; the secondary output signal of the sensor's internal use of the double-twisted shielded cable sleeve acts on the corresponding pins of the sensor's internal signal RJ45 shielded output cable, realizing the split type of the secondary signal and the integrated output structure of the sleeve and the sensor; both shielded wires are designed with shielded wires, which play an anti-interference shielding function in the output of the secondary signal; among them, the CAT6 standard RJ45 shielded output cable line reduces the influence of EMI, maintains data integrity and improves high-speed performance.

[0030] In this embodiment, the sleeve secondary signal element is the total inductance of the coil wound on the high inductance skeleton of the sensor itself, which is converted to realize the self-integral voltage signal for the downstream measurement and protection device collection in the power distribution network; the transformer body is a high inductance skeleton, a secondary coil, a shield cover, and an RJ45 secondary output shielded wire which are poured together with epoxy insulating glue inside the shell. Two bolts are designed at the lower end of the transformer body, which can be used by users for installation and fixation.

[0031] In this embodiment, the core component of the sensor is its high inductance skeleton, which not only provides physical support for the wound coil, but also greatly improves the inductance value of the sensor through its special material and structure design; this makes the sensor be able to provide higher sensitivity and more stable performance without increasing the size; the winding inside the sensor is composed of coils uniformly wound on the high inductance skeleton, the ends of which are connected to form a closed loop to reduce electromagnetic interference and improve signal quality; this design not only improves the response speed of the sensor, but also enables it to maintain linear response in a wide frequency range, which is very suitable for detecting rapidly changing current signals such as transient processes or fault currents in power systems; the composite shielding layer is composed of a stainless steel shield cover and a copper foil wrapped on the coil, which further enhances the anti-interference ability of the sensor; this double shielding design effectively isolates the interference of external electromagnetic fields, ensuring the purity and stability of the output signal; in addition, the entire sensor is sealed with epoxy resin insulating casting material, which not only enhances the mechanical strength, but also provides excellent electrical insulation performance, ensuring the reliable operation of the equipment in harsh environments; The sleeve secondary signal element refers to the function of the sensor itself converting the total inductance of the coil wound on the high inductance skeleton to realize the self-integral voltage signal; this feature enables the sensor to directly generate a voltage signal proportional to the primary current, without the need for additional integration circuits for downstream measurement and protection devices in the power distribution network; this design simplifies the system integration process, reduces costs, and improves the overall system reliability; The transformer body includes key components such as a high inductance skeleton, a secondary coil, a shielding cover and an RJ45 secondary output shielding line, which are all cast together with epoxy insulating glue inside the shell to form a solid and compact whole. This integrated design not only improves the durability and protection level of the device, but also facilitates on-site installation and maintenance. In particular, two bolts are designed at the lower end of the transformer body, providing a simple and effective fixing solution that allows the sensor to be easily installed on various supports or panels, adapting to different application scenarios.

[0032] In this embodiment, the enameled copper wire is uniformly wound on a ring-shaped non-magnetic high inductance skeleton, the current-carrying wire carrying the measured current is placed in the ring of the air core coil, a sleeve secondary signal element is then added at the secondary output end, and a secondary output cable is welded, and finally the elements are cast in the shell with epoxy resin.

[0033] In this embodiment, the manufacturing process of the sleeve through type Rogowski coil current sensor embodies the deep integration of precision engineering and electromagnetic measurement principles. The enameled copper wire is uniformly wound on a ring-shaped non-magnetic high inductance skeleton. This non-magnetic material not only avoids the magnetic saturation problem that may occur in traditional iron core transformers under high current, but also ensures excellent linearity and frequency response characteristics of the sensor in the entire wide frequency band. The enameled copper wire, as the winding material, has good electrical conductivity and insulation strength, and the insulating paint layer on its surface effectively prevents turn-to-turn short circuit and ensures the electrical stability of the winding in long-term operation. During assembly, the primary current-carrying wire carrying the measured current is passed through the center hole of the air core coil to form a through structure. According to Faraday's law of electromagnetic induction, the alternating magnetic field generated by the change of primary current induces an electromotive force in the coil proportional to the rate of current change. To effectively process the original induced signal, a sleeve secondary signal element is added at the secondary output end of the sensor. This element is essentially a self-integration circuit structure based on high inductance characteristics, which can directly convert the induced voltage signal into an output voltage proportional to the primary current, eliminating the need for an external integrator required by traditional Rogowski coils, thereby simplifying the system architecture, improving reliability and reducing installation cost. The combined secondary output cable is welded to the output terminal of the signal element, and a shielding structure is designed to further suppress high frequency noise and external electromagnetic interference. All internal components, including the high inductance skeleton, winding, signal element, connection welding point and part of the cable root, are injected with high-performance epoxy resin insulating casting material and packaged in a solid shell. Epoxy resin not only provides excellent electrical insulation performance and mechanical support, but also effectively prevents moisture, corrosion and vibration, making the sensor suitable for harsh operating environments such as outdoor substations and industrial distribution cabinets.

[0034] The whole manufacturing process takes into account electromagnetic performance, structural strength and environmental adaptability, so that the current sensor shows excellent application value in key fields such as smart grid, new energy access, power quality monitoring and relay protection.

[0035] In the embodiment, the sensor is mainly used in the electrical cabinet such as the ring main unit, and is installed at the connection between the primary sleeve of the incoming line end or outgoing line end of the ring main unit and the primary cable head. The primary sleeve or primary cable of the ring main unit passes through the center hole of the mutual inductor, thereby forming the primary part of the sensor. According to the Faraday's law of electromagnetic induction, the coil acts on the high inductance skeleton to output stable secondary signals. The proportional signal induced by the secondary inductor is converted through processing, and is output to the terminal of the cabinet through the secondary cable, for use in metering, monitoring or protection terminal equipment. With the intelligentization and integration development of the power grid, the ring main unit and a series of electrical cabinets will be designed to be more compact and smaller. Since the conventional mutual inductor operates according to the principle of electro-magnetic induction, it is difficult for the shape and size of the conventional mutual inductor to meet the design requirements of the latest ring main unit and other electrical cabinet manufacturers. The application of the sleeve-penetration type Rogowski coil current sensor of the utility model fully meets the latest intelligentization and inductive material inductance conversion into secondary voltage output, stable high integration development trend, which effectively solves the problem to a great extent. The overall design is exquisite and small, the measurement range is wider, the precision is higher, the error curve is better, and the output signal of the sleeve-penetration type Rogowski coil skeleton type current transformer is essentially the induced voltage of the measured current change rate, which is restored to the original current waveform through the coil self-integration characteristic or external integration circuit. Its high linearity, wide frequency response and anti-interference ability make it have obvious advantages in high-voltage power grid fault positioning, intelligent device monitoring and other fields.

[0036] In the embodiment, the special interference signal shielding function is also designed. In the normal operation and use process of the sensor, different installation and use environments will have different degrees of signal interference and different types of signal interference. The shielding layer designed in the sensor can effectively shield the interference signals around the sensor and introduce them into the ground through the safety ground wire, thereby forming an effective anti-interference measure to ensure the stability and high reliability of the secondary output signal of the sensor.

[0037] In the embodiment, the output signal processing is designed and the output signal characteristics are provided; in the normal operation of the sensor, the signal acquisition is met through the winding of the coil, the signal of the inductive voltage of the coil and the self-integration characteristics or the built-in wideband integrator restore the differential signal through the current of the cable; the self-integration characteristics of high frequency and low frequency and the digital correction module meet the compensation of high frequency signal attenuation, and ensure the fidelity of different transient signals such as line wave pulses. The output voltage signal meets the coverage of 0.1Hz-10MHz, supports power frequency steady-state measurement and nanosecond-level transient pulse at the same time, and the linearity of the output meets the non-magnetic core saturation, the linearity is better than 0.5%, and is suitable for wide range measurement from 5A to 50kA; it can be seen that the sleeve through type Rogowski coil current sensor has the advantages of wide measurement range, higher precision, no saturation, strong anti-interference ability, wide frequency response, low noise, stable transmission signal, small size, convenient installation, and is more suitable for current sensor in the field of intelligent power grid upgrading and high voltage equipment monitoring.

[0038] The basic principles, main features and advantages of the present application are shown and described above. Those skilled in the art should understand that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only preferred examples of the present application and are not intended to limit the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A bushing-type through-hole Rogowski coil current sensor, characterized in that, The device includes a high-inductance frame (1), a winding (2), a composite shielding layer (3), an epoxy resin insulating casting material (4), a bushing secondary signal element (5), a fixing bolt (6), a combined secondary signal output cable (7), and a sensor housing (8). The winding includes a coil uniformly wound on the high-inductance frame, and the end of the coil is connected to a return turn to form a closed loop. The composite shielding layer is composed of a stainless steel shield and copper foil covering the coil.

2. The bushing-type through-hole Rogowski coil current sensor as described in claim 1, characterized in that, The entire coil of the winding is uniformly wound on a toroidal non-magnetic high-inductance frame. The current-carrying wire carrying the measured current is placed inside the toroidal non-magnetic high-inductance frame of the air-core coil and is parallel to the axis of the toroidal non-magnetic high-inductance frame.

3. A bushing-type through-hole Rogowski coil current sensor as described in claim 2, characterized in that, For a sinusoidal current in steady state, the output voltage of an air-core coil can be expressed as: e = M·jω·I; Where I represents the measured current, M represents the mutual inductance coefficient, ω represents the angular frequency of the sinusoidal current, and e represents the output voltage of the air-core coil.

4. A bushing-type through-hole Rogowski coil current sensor as described in claim 2, characterized in that, The coils on the high-inductance frame generate an inductance self-integration function to convert the signal into a secondary signal.

5. A bushing-type through-hole Rogowski coil current sensor as described in claim 1, characterized in that, The sensor housing is internally embedded with a high-inductance frame, windings, epoxy resin insulating casting material, sleeve secondary signal elements, and combined secondary signal output cables.

6. A bushing-type through-hole Rogowski coil current sensor as described in claim 5, characterized in that, After placing the current-carrying wire carrying the measured current in the high-inductance frame, the bushing secondary signal element is installed at the secondary output end, and the combined secondary signal output cable is welded in. The cable is then cast into the sensor housing through the epoxy resin insulating casting material.

7. A bushing-type through-hole Rogowski coil current sensor as described in claim 5, characterized in that, The sensor, composed of a high-inductance frame, windings, and epoxy resin insulating casting material, senses a corresponding proportional current signal. This signal is then converted by a secondary signal element in a bushing to output a small analog voltage signal. Finally, the signal is output to the client for metering via a combined secondary signal output cable.

8. A bushing-type through-hole Rogowski coil current sensor as described in claim 1, characterized in that, The sensor's internal secondary signal element shielding uses a twisted-pair shielded cable to shield the corresponding pins of the secondary signal output cable.

9. A bushing-type through-hole Rogowski coil current sensor as described in claim 1, characterized in that, The fixing bolt is located at the bottom of the sensor.

10. A bushing-type through-hole Rogowski coil current sensor as described in claim 1, characterized in that, The lower end of the sensor is equipped with a sealing ring, which is combined with the secondary signal output cable for sealing and limiting.

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