Voltage and current combined transformer for ring main unit

Abstract

The utility model relates to the field of power equipment measurement, in particular to a voltage and current combined transformer for a ring main unit. The utility model provides a combined mutual inductor which comprises a conducting rod, an insulating sleeve wrapping the conducting rod and a shielding network arranged in the insulating sleeve. An insulating layer is arranged between the shielding network and the conducting rod, a primary capacitor is formed between the shielding network and the conducting rod, the shielding network comprises a first shielding net and a second shielding net which are electrically connected, the shielding network is connected with a secondary capacitor, and the secondary capacitor and the primary capacitor form a capacitance voltage dividing structure of the voltage transformer. And the current transformer is arranged around the conducting rod. According to the utility model, integration of voltage and current measurement functions is realized, and the device has the advantages of compact structure, high measurement precision, strong anti-interference capability and the like, is especially suitable for being used in a ring main unit with a limited space, and can improve the monitoring and protection capability of an electric power system.

Description

Technical Field

[0001] The utility model relates to the field of power equipment measurement, in particular to a voltage-current combined transformer for a ring main unit. Background Art

[0002] In the power system, accurately measuring voltage and current is the key to ensuring the safe operation of the system. Traditional voltage transformers and current transformers are usually designed and installed separately, and this method will face the problem of difficult installation in a ring main unit with limited space. In addition, the separate design also increases the complexity and cost of the equipment.

[0003] Existing voltage transformers often face the problem of insufficient accuracy when measuring high voltages, especially in an environment with electromagnetic interference. This accuracy problem may affect the monitoring and protection functions of the power system, increasing the risk of system failures.

[0004] At the same time, traditional current transformers often need to replace devices of different specifications when measuring a wide range of currents, which not only increases the maintenance cost but also reduces the flexibility of the system. Under rapidly changing load conditions, this limitation may lead to a decrease in measurement accuracy.

[0005] In addition, existing transformers generally lack effective electromagnetic shielding measures, making them vulnerable to interference in a complex electromagnetic environment and affecting the reliability of measurement results. This interference may not only cause measurement errors but also affect the normal operation of adjacent devices.

[0006] In the application of ring main units, the compactness and integration of equipment are particularly important. However, existing transformer designs often have difficulty achieving high accuracy, wide range, and good electromagnetic compatibility simultaneously in a limited space. This design limitation restricts the overall performance and reliability of the ring main unit. Summary of the Utility Model

[0007] The purpose of the utility model is to provide a voltage-current combined transformer for a ring main unit to solve the problems of difficult installation and high cost in the prior art.

[0008] To achieve the above purpose, the utility model provides a voltage-current combined transformer for a ring main unit, including: a conductive rod; an insulating sleeve wrapping the conductive rod; a shielding network disposed in the insulating sleeve, an insulating layer is provided between the shielding network and the conductive rod, and a primary capacitance is formed between the shielding network and the conductive rod.

[0009] Further, the shielding network includes a first shielding net and a second shielding net, the first shielding net and the second shielding net are arranged at different axial positions along the conductive rod, and the first shielding net is electrically connected to the second shielding net.

[0010] Specifically, the insulating layer is epoxy resin.

[0011] Furthermore, it further includes a secondary capacitor connected to the shielding network, and the secondary capacitor and the primary capacitor together form a capacitive voltage division structure of the voltage transformer.

[0012] More specifically, the rated voltage of the voltage transformer is (5kV / √3 to 20kV / √3):(1V / √3 to 5V / √3).

[0013] In addition, the combined voltage and current transformer for the ring main unit further includes a current transformer disposed around the conductive rod.

[0014] Furthermore, the current transformer includes: a current amorphous core disposed around the conductive rod; a current coil wound around the current amorphous core; and a current signal shielding double winding electrically connected to the current coil.

[0015] Specifically, the rated current of the current transformer is (20A to 1000A):0.225V.

[0016] Even further, the combined voltage and current transformer for the ring main unit further includes a non-inductive resistor electrically connected to the current transformer.

[0017] In addition, the insulating bushing is epoxy resin.

[0018] For the combined voltage and current transformer for the ring main unit provided by the present utility model, by arranging an insulating layer between the shielding network and the conductive rod to form a primary capacitor and connecting the shielding network to a secondary capacitor, a capacitive voltage division structure is gradually formed, effectively improving the integration degree of voltage measurement. Secondly, a current transformer is also provided to realize the integration of voltage and current measurement functions, and electromagnetic interference is reduced through the arrangement of the shielding network, thereby improving the reliability and stability of measurement.

[0019] Furthermore, by arranging and electrically connecting a first shielding net and a second shielding net at different axial positions, the configuration difficulty of the combined voltage and current transformer is reduced. The designs of the voltage transformer and the current transformer enable the device to maintain high-precision measurement within a wide voltage and current range. The introduction of the non-inductive resistor further optimizes signal processing, and the use of the epoxy resin insulating bushing improves the insulation performance and durability of the device. These features work together to significantly improve the combined voltage and current transformer for the ring main unit of the present utility model in terms of compactness, measurement accuracy, anti-interference ability and application range, and it is particularly suitable for use in a ring main unit with limited space. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1Schematic diagram of the overall structure of a voltage-current combined transformer for a ring main unit in an embodiment of the present utility model;

[0021] Figure 2 Schematic diagram of the structural principle of a voltage transformer in an embodiment of the present utility model;

[0022] Figure 3 Schematic diagram of the structural principle of a current transformer in an embodiment of the present utility model.

[0023] In the figure: 1, conductive rod; 2, insulating sleeve; 3, first shielding net; 4, first shielding net fixing member; 5, voltage signal shielded twisted pair; 6, voltage secondary signal converter; 7, second shielding net fixing member; 8, second shielding net; 9, current signal shielded twisted pair; 10, current coil; 11, current amorphous iron core; 12, non-inductive resistor. Specific embodiments

[0024] The technical solutions of the present utility model will be elaborated in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the described embodiments are only used to explain the technical principle of the present utility model, rather than limiting the scope of its patent protection. Those skilled in the art should understand that various transformations, modifications or equivalent replacements can be made to these embodiments without departing from the spirit and scope of the present utility model. These transformations, modifications or equivalent replacements should all be regarded as falling within the protection scope defined by the claims of the patent of the present utility model. The specific embodiments of the present utility model have been described by way of examples. However, it should be understood that the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0025] As Figure 1 shown, a voltage-current combined transformer for a ring main unit provided by the present utility model includes a conductive rod 1, an insulating sleeve 2, a shielding network, a voltage transformer and a current transformer. The conductive rod 1 serves as the main current path and is preferably made of a highly conductive material such as copper or aluminum. The insulating sleeve 2 wraps the conductive rod 1 to provide necessary insulation protection. Preferably, the insulating sleeve 2 is made of epoxy resin material, which has excellent insulation performance and mechanical strength.

[0026] The shielding network is arranged inside the insulating sleeve 2 and includes a first shielding net 3 and a second shielding net 8. The first shielding net 3 is installed on the insulating sleeve 2 through a first shielding net fixing member 4, and its position is biased towards the left end of the conductive rod 1. The second shielding net 8 is installed on the insulating sleeve 2 through a second shielding net fixing member 7, and its position is biased towards the right end of the conductive rod 1.

[0027] In a specific embodiment, the first shielding net 3 and the second shielding net 8 are connected by a welding process to form an integral shielding network structure. The integral shielding network is isolated from the conductive rod 1 by an epoxy resin material to form a primary capacitor with a specific capacitance value. This structure not only enhances the overall shielding effect but also provides a basis for capacitive voltage division for subsequent voltage measurement.

[0028] As Figure 1 shown, the voltage transformer includes a voltage signal shielded twisted pair 5 and a voltage secondary signal converter 6. One end of the voltage signal shielded twisted pair 5 is for output, and the other end is connected to one end of the voltage secondary signal converter 6; the other end of the voltage secondary signal converter 6 is connected to the shielding network. The voltage transformer utilizes the principle of capacitive voltage division between the shielding net and the conductive rod. Specifically, a secondary capacitor is provided inside the voltage secondary signal converter 6, and the primary capacitor and the secondary capacitor together form a capacitive voltage division structure of the voltage transformer, reducing the high voltage to a measurable level. This design simplifies the structure.

[0029] As Figure 2 shown, in order to prevent the primary capacitor from being broken down by C1 and affecting the secondary circuit, a discharge tube (not shown in the figure) is connected in parallel to the secondary capacitor provided inside the voltage secondary signal converter. When the primary capacitor C1 breaks down, the voltage penetrating to the secondary capacitor C2 is directly zero, protecting the secondary capacitor C2 from damage. At the same time, a resistor R1 is connected in parallel to the secondary capacitor C2 to play a role in phase difference adjustment.

[0030] As Figure 1 shown, the output terminals of the voltage transformer are marked as u+ and u-. Among them, u+ represents the positive output terminal of the voltage signal, and u- represents the negative output terminal of the voltage signal. These two terminals provide a low-voltage measurement signal after capacitive voltage division and can be directly connected to the corresponding measurement equipment or control system to monitor the voltage status in the ring main unit.

[0031] The rated voltage of the voltage transformer is preferably 13.8 kV / √3:3.25 V / √3 V. This rated voltage range is applicable to most medium-voltage distribution systems and can meet the common application requirements of the ring main unit. In addition, the measurement accuracy of the voltage transformer of the present utility model reaches level 1, which means that its measurement error does not exceed ±1% of the rated value, and it can provide high-precision voltage measurement results.

[0032] As Figure 1As shown, the current transformer includes a current amorphous core 11 that surrounds the conductive rod 1; a current coil 10 wound around the current amorphous core 11; and a current signal shielding twisted pair 9 that is electrically connected to the current coil 10. The current amorphous core 11 is preferably a small-sized high-performance current amorphous core. As Figure 3 As shown, the current transformer part adopts the design principle of a small-sized core coil type with low power. This current transformer consists of a primary winding, the current amorphous core 11, and a low-loss secondary winding. The secondary winding is connected to an integrated component Ra (not shown in the figure). This design makes the secondary output a voltage signal. When the primary current passes through the primary winding ports P1 and P2, a secondary current I2 is induced in the secondary winding. This secondary current I2 flows through the integrated component R, generating a voltage drop Us. The amplitude of the voltage drop Us is proportional to the primary current and the phase remains consistent. An important feature of this structure is that by reducing the internal loss of the transformer and the power of the secondary load, the measurement range can be expanded to a certain extent and the measurement accuracy can be improved. Specifically, the smaller the internal loss and the power of the secondary load, the wider the measurement range of the transformer and the higher the accuracy. This low-power structure not only improves the measurement performance but also reduces the equipment volume, making it more suitable for use in ring main units with limited space.

[0033] As Figure 1 and Figure 3 As shown, the secondary output terminals of the current transformer are marked as S1 and S2. These two terminals represent the two ends of the secondary winding of the current transformer and provide a low-current signal output proportional to the primary current. These two terminals can be connected to the corresponding measuring instruments or protection devices to monitor the current status in the ring main unit.

[0034] The rated current of the current transformer is preferably 800A:0.225V or 40A:0.225V. These two rated current specifications can cover most application scenarios of ring main units and meet the measurement requirements under different load conditions. At the same time, the current transformer of the present utility model also reaches Class 1 accuracy, that is, its measurement error does not exceed ±1% of the rated value, ensuring high-precision current measurement.

[0035] In addition, the voltage-current combined transformer for a ring main unit of the present utility model further includes a non-inductive resistor 12, and the non-inductive resistor 12 is electrically connected to the current transformer. The introduction of the non-inductive resistor 12 can optimize signal processing and improve measurement accuracy.

[0036] The voltage-current combined transformer for a ring main unit proposed by the present utility model has certain environmental adaptability and performance characteristics. Its structure enables the equipment to operate normally within a wide temperature range, applicable to an environmental temperature of -40°C to +70°C. The insulation performance and structural strength of the equipment enable it to operate reliably in areas below 1000 meters above sea level.

[0037] Through the adopted sealing technology and material selection, the utility model can maintain stable performance in an environment containing pollutants such as a small amount of dust, smoke, corrosive gas, steam or salt. The moisture-proof structure of the equipment ensures its normal operation in an environment with a relatively high humidity. Even under the condition that the average relative humidity reaches 95% within 24 hours, it can still maintain stable performance.

[0038] The insulation structure and materials adopted for the voltage transformer part of the utility model enable it to operate reliably for a long time under 1.9 times the rated voltage, greatly improving the overload capacity and safety of the equipment. Similarly, through the optimized magnetic circuit structure and material selection for the current transformer part, it realizes long-term stable operation under 2 times the rated current, and to a certain extent improves the overload capacity and measurement range of the equipment.

[0039] These performance characteristics enable the utility model to maintain high precision and reliability in various complex working environments, providing a strong guarantee for the safe and stable operation of the power system.

[0040] The combined voltage and current transformer for ring main unit of the utility model realizes the integration of voltage and current measurement functions through an improved structure. The structure of the multi-layer shielding network reduces electromagnetic interference to a certain extent and improves the measurement accuracy. The optimized structures of the voltage transformer and current transformer enable the equipment to maintain high-precision measurement within a wide range of voltages and currents. The introduction of non-inductive resistors further optimizes the signal processing. The use of epoxy resin insulating sleeves improves the insulation performance and durability of the equipment. The combination of these features makes the combined voltage and current transformer for ring main unit of the utility model have certain improvements in terms of compactness, measurement accuracy, anti-interference ability and application range, and is especially suitable for use in ring main units with limited space. This structure not only simplifies the installation process, reduces costs, but also improves the reliability and stability of the entire measurement system.

[0041] The utility model has been described in detail through the above specific embodiments. However, it should be understood that the above content is only illustrative and not used to limit the scope of the utility model. Those of ordinary skill in the art can make various modifications and variations to the utility model according to the specific application scenarios and actual needs without departing from the spirit and scope of the utility model, and these modifications and variations are within the protection scope of the utility model.

Claims

1. A voltage and current combined mutual inductor for a ring main unit, characterized in that Comprising: A conductive rod; An insulating sleeve that wraps the conductive rod; A shielding network disposed within the insulating sleeve, with an insulating layer provided between the shielding network and the conductive rod, and a primary capacitance formed between the shielding network and the conductive rod.

2. The voltage-current combined transformer for ring main unit according to claim 1, wherein The shielding network includes a first shielding mesh and a second shielding mesh, the first shielding mesh and the second shielding mesh are disposed at different axial positions along the conductive rod, and the first shielding mesh is electrically connected to the second shielding mesh.

3. The voltage-current combined transformer for a ring main unit according to claim 1, wherein, The insulating layer is epoxy resin.

4. The voltage-current combined transformer for ring main unit according to claim 1, wherein, It further includes a secondary capacitance connected to the shielding network, and the secondary capacitance and the primary capacitance together form a capacitive voltage division structure of a voltage transformer.

5. The voltage-current combined transformer for ring main unit according to claim 4, characterized in that The rated voltage of the voltage transformer is (5kV / √3 to 20kV / √3):(1V / √3 to 5V / √3).

6. The voltage-current combined transformer for ring main unit according to claim 1, wherein, It further includes a current transformer disposed around the conductive rod.

7. The voltage-current combined transformer for ring main unit according to claim 6, characterized in that, The current transformer includes: A current amorphous core that surrounds the conductive rod; A current coil wound around the current amorphous core; and A current signal shielding double winding that is electrically connected to the current coil.

8. The voltage-current combined transformer for ring main unit according to claim 6, characterized in that, The rated current of the current transformer is (20A to 1000A):0.225V.

9. The combined voltage and current transformer for ring main unit according to claim 6, characterized in that, It further includes a non-inductive resistor, and the non-inductive resistor is electrically connected to the current transformer.

10. The voltage-current combined transformer for ring main unit according to claim 1, wherein The insulating sleeve is epoxy resin.

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