Maintenance-free intelligent explosion-proof circuit breaker and three-phase current sensor thereof

Abstract

The utility model provides a maintenance-free intelligent explosion-proof circuit breaker and a three-phase current sensor thereof. The maintenance-free intelligent explosion-proof circuit breaker comprises a housing; the phase sequence coil is arranged in the shell; the zero sequence coil is arranged in the shell; the organic pouring sealant is filled among the phase sequence coil, the zero sequence coil and the shell; and the non-inductive resistor is arranged on the side wall in the shell and is connected in parallel with the secondary wire outlet end of the current coil so as to be suitable for an underground coal mine with explosive hazardous gas. A power supply system with a three-phase alternating-current neutral point not directly grounded outputs small signals and can be used for current control, protection and measurement of a circuit breaker, and the explosive-proof performance and the electrical performance both meet national standard and industrial standard requirements.

Description

Technical Field

[0001] The utility model relates to the technical field of automatic control, in particular to the field of three-phase current sensors of maintenance-free intelligent explosion-proof circuit breakers. Background Art

[0002] With the rapid development of the industrial field and the continuous advancement of technological progress, explosion-proof circuit breakers, as an important electrical protection device, are playing an increasingly significant role in ensuring the safe and stable operation of industrial equipment. Especially in high-risk industries such as petroleum, chemical, and coal mines, the wide application of explosion-proof circuit breakers has become a key link in ensuring production safety. The increasing dependence of these industries on explosion-proof circuit breakers has also driven the continuous rise in market demand.

[0003] At present, the electromagnetic current transformers for explosion protection on the market are large in volume, have many circuit wiring, and there are problems in product withstand voltage, partial discharge, and lightning impulse. Moreover, their performance and functions are single, and they cannot achieve the integration of three-phase phase-zero integrated current sensors. Due to the problem of magnetic saturation, it is difficult for electromagnetic current transformers to achieve large-range measurement, and it is difficult for a single electromagnetic current transformer to meet the needs of high-precision metering and relay protection at the same time. The harm caused by the secondary open circuit of traditional electromagnetic current transformers to equipment and personnel, especially when used in coal mines, greatly reduces the safety and reliability. And traditional electromagnetic current transformers are analog output, which cannot meet the requirements of digital substations.

[0004] Therefore, it is urgent to invent a maintenance-free intelligent explosion-proof circuit breaker and its three-phase current sensor to effectively solve the above technical problems. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a maintenance-free intelligent explosion-proof circuit breaker and its three-phase current sensor to effectively solve at least one of the problems in the AC current sensor that is applicable to coal mine shafts with explosive dangerous gases, a power supply system where the three-phase AC neutral point is not directly grounded, has a small signal output, can be used for current control, protection, and measurement of the circuit breaker, and whose explosion-proof performance and electrical performance meet the requirements of national standards and industry standards.

[0006] To achieve the above purpose, the utility model provides a three-phase current sensor for a maintenance-free intelligent explosion-proof circuit breaker, including:

[0007] A housing;

[0008] Phase sequence coils, arranged inside the housing;

[0009] Zero sequence coils, arranged inside the housing;

[0010] Organic potting glue, filled between the phase sequence coils, the zero sequence coils, and the housing;

[0011] The non-inductive resistor is arranged at the side wall inside the housing and is connected in parallel to the secondary outgoing terminal of the current coil.

[0012] Furthermore, the secondary outgoing line of the current sensor uses a mining flame-retardant shielded five-core cable.

[0013] Furthermore, the inner core of the mining flame-retardant shielded five-core cable is made of oxygen-free purple copper, and the material of the outer insulation is polyurethane.

[0014] Furthermore, the material of the housing is flame-retardant ABS composite engineering plastic.

[0015] Furthermore, the material of the phase sequence coil is nano-gold alloy and high-quality silicon steel sheet.

[0016] Furthermore, the zero-sequence coil adopts the principle of three-phase current magnetic potential synthesis.

[0017] Furthermore, the material of the iron core in the zero-sequence coil is permalloy.

[0018] Furthermore, the outer surfaces of both the phase sequence coil and the zero-sequence coil are wrapped with copper braid and semi-conductive corrugated paper.

[0019] Furthermore, the number of the phase sequence coils is 3, and the number of the zero-sequence coils is 3.

[0020] The present utility model also provides a maintenance-free intelligent explosion-proof circuit breaker, which adopts the three-phase current sensor made of the above materials.

[0021] Compared with the prior art, the beneficial effects of the present utility model are mainly reflected in: providing a maintenance-free intelligent explosion-proof circuit breaker and its three-phase current sensor, which are applicable to the coal mine underground with explosive dangerous gases. The three-phase AC neutral point is not directly grounded in the power supply system, and the small signal output can be used for the current control, protection and measurement of the circuit breaker, and both the explosion-proof performance and the electrical performance meet the requirements of national standards and industry standards. Brief Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present utility model;

[0023] Figure 2 It is the electrical schematic diagram of the current sensor of an embodiment of the present utility model;

[0024] Figure 3 It is the coil design schematic diagram of the current sensor of an embodiment of the present utility model.

[0025] In the figure, 101, housing; 102, organic potting compound; 104, zero-sequence coil; 105, non-inductive resistor; 106, mining flame-retardant shielded five-core cable. Detailed implementation mode

[0026] The following will combine the accompanying drawings to describe a maintenance-free intelligent explosion-proof circuit breaker and its three-phase current sensor of the present utility model in more detail. The preferred embodiments of the present utility model are shown, and it should be understood that those skilled in the art can modify the present utility model described herein while still achieving the advantageous effects of the present utility model. Therefore, the following description should be understood as broad knowledge for those skilled in the art and not as a limitation to the present utility model.

[0027] In the following paragraphs, the present utility model will be described more specifically by way of example with reference to the accompanying drawings. According to the following description, the advantages and features of the present utility model will be clearer. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise scales, only for the purpose of conveniently and clearly assisting in explaining the embodiments of the present utility model.

[0028] As Figure 1 shown, this embodiment proposes a three-phase current sensor for a maintenance-free intelligent explosion-proof circuit breaker, including:

[0029] A housing 101;

[0030] Phase sequence coils, arranged inside the housing 101, used to provide a magnetic flux path, improve the magnetic permeability of the magnetic circuit, and reduce the eddy current loss of the iron core;

[0031] Zero-sequence coil 104, arranged inside the housing 101, used to provide a magnetic flux path, improve the magnetic permeability of the magnetic circuit, and reduce the eddy current loss of the iron core;

[0032] Organic potting glue 102, filled between the phase sequence coil 103, the zero-sequence coil 104, and the housing 100, used for insulation and heat dissipation;

[0033] A non-inductive resistor 105, arranged on the side wall inside the housing 101, connected in parallel to the secondary output terminal of the current coil, capable of converting a small current signal into a small voltage signal.

[0034] The phase sequence coil 103 is usually used to detect the phase sequence of the current in a three-phase system. In a three-phase system, the phase sequence of the current refers to the order of the current in three phases. The setting of the phase sequence coil 103 usually involves three independent coils, each coil corresponding to one phase, and these coils can be current transformers (CTs). For reference, see Figure 2As shown, taking the number of phase sequence coils 103 as 3 as an example, it includes a current transformer TA1 for phase A, a current transformer TA2 for phase B, and a current transformer TA3 for phase C. They are respectively wound around the three-phase wires and are used to measure the current of each phase. The setting of the phase sequence coils 103 helps to ensure that the current in the system flows in the correct order, which is crucial for the rotation direction of the motor and the stable operation of the system.

[0035] Correspondingly, for the non-inductive resistor 105, it specifically includes a secondary current load R1 for phase A, connected in parallel at the secondary outgoing terminal AS1 of phase A; a secondary current load R2 for phase B, connected in parallel at the secondary outgoing terminal BS1 of phase B, and a secondary current load R3 for phase C, connected in parallel at the secondary outgoing terminal CS1 of phase C.

[0036] The zero-sequence coil 104, also known as the zero-sequence current transformer, is used to detect the zero-sequence current in the three-phase system. The zero-sequence current usually appears when a ground fault or unbalanced load occurs, and it is a non-zero value of the vector sum of the three-phase currents. The setting of the zero-sequence coil 104 can be to let the three-phase wires pass through a zero-sequence current transformer together, or to install a zero-sequence CT on the neutral line N. When the three-phase load is completely balanced and there is no ground fault, the zero-sequence current should be zero. If there is an imbalance or ground fault, the zero-sequence current will not be zero, and at this time, the zero-sequence coil 104 can detect this abnormal situation and trigger the protection device to act, such as cutting off the power supply or sending an alarm.

[0037] Please continue to refer to Figure 2 , taking the number of zero-sequence coils 104 as 3 as an example, the three-phase wires pass through a zero-sequence current transformer TA4 together. Correspondingly, for the non-inductive resistor 105, it also includes a zero-sequence secondary current load R4 connected in parallel at the secondary outgoing terminal NS1.

[0038] In practical applications, the setting of the zero-sequence coil 104 needs to consider the grounding method of the system and possible fault types. For example, in a high-voltage distribution system, the grounding method of the neutral point may directly affect the setting of the zero-sequence coil 104 and the detection of the zero-sequence current. In some systems, the transformation ratio (K) of the zero-sequence current transformer is small, which helps to improve the detection accuracy and anti-interference ability.

[0039] In addition, there is also a zero-sequence circulating current suppression algorithm based on a three-phase PWM rectifier, which suppresses the zero-sequence circulating current in the circuit by adjusting the action time of the zero vector in SVPWM (Space Vector Pulse Width Modulation), thereby improving the performance and stability of the circuit.

[0040] In this embodiment, the secondary outgoing line of the current sensor uses a mining flame-retardant shielded five-core cable 106, which is used to directly transmit the secondary voltage signal of the current sensor to the terminal, that is, output a small voltage signal.

[0041] In a specific example, all primary and secondary parts of the current sensor are integrated within the sensor housing 101, and parameters such as phase sequence current, zero sequence current, and power of the circuit breaker are monitored online through signal transmission. The present invention belongs to a low-power core current sensor (LPCT). LPCT has the characteristics of high output sensitivity, mature technology, stable performance, and being easy for mass production; in addition, due to its small secondary load and the application of high-permeability core materials, it can achieve the measurement of currents with a large dynamic range.

[0042] The formula for measuring voltage in this embodiment is:

[0043]

[0044] Reference can be made to Figure 3 the schematic diagram of the coil design of the current sensor according to an embodiment of the present utility model shown in the figure, where V s is the secondary side voltage, which is the voltage signal generated by connecting a sampling resistor R sh in parallel on the secondary side; N P , N S are the number of turns of the primary side and secondary side coil windings respectively, I is the current flowing through the primary side winding of the current transformer; R b is the load carried.

[0045] Furthermore, the inner core of the mining flame-retardant shielded five-core cable 106 is made of oxygen-free purple copper, and the outer insulation material is polyurethane, which has the characteristics of flame retardancy, high temperature resistance, and strong anti-interference ability, and can be directly interfaced with instruments and relay protection devices to achieve the functions of metering, control, measurement, and protection.

[0046] Specifically, the material of the housing 101 is flame-retardant ABS composite engineering plastic, which has good thermal stability, good fire resistance, no pollution, and can resist magnetic field interference.

[0047] In an alternative embodiment, the organic potting adhesive 102 can be well cured without heating. The organic potting adhesive 102 can be a room-temperature curing epoxy potting adhesive or room-temperature vulcanizing silicone rubber or silicone gel, etc. The cured elastomer has the following characteristics: 1. Resist moisture, dirt, and other atmospheric components. 2. Alleviate mechanical stress and tension caused by mechanical, thermal shock, and vibration. 3. Good high-frequency electrical performance. 4. Good adhesion performance. 5. Can be used between -50 and 150 °C.

[0048] Furthermore, the material of the phase sequence coil 103 is nano gold alloy and / or high-quality silicon steel sheet alone or in combination, and its performance can meet both measurement-level parameters and protection-level parameters.

[0049] In this example, the zero-sequence coil 104 adopts the principle of three-phase current magnetic potential synthesis, and the core is made of Permalloy IJ85 material, which has outstanding performance, better magnetic properties than silicon steel material, and higher temperature stability and aging stability.

[0050] Furthermore, the non-inductive resistor 105 is made of precision metal foil and packaged with alumina ceramics, and has the characteristics of low temperature drift and good heat dissipation.

[0051] Furthermore, the outer surfaces of the phase sequence coil 103 and the zero sequence coil 104 are both wrapped with copper braided tape and semi-conductive corrugated paper. This technology is a double shielding technology of copper braided tape and semi-conductive corrugated paper, which can make the partial discharge performance index more excellent.

[0052] This embodiment also provides a maintenance-free intelligent explosion-proof circuit breaker, which uses the three-phase current sensor described in the above material.

[0053] In summary, this embodiment provides a maintenance-free intelligent explosion-proof circuit breaker and a three-phase current sensor thereof, which achieve the following performance:

[0054] 1. Ambient temperature: -40℃∽+70℃.

[0055] 2. High precision: 0.1S / 0.2S level. This is mainly due to the following characteristics of this three-phase current sensor:

[0056] (1) The working temperature rise of the utility model is small, generally only about 1°C. The temperature characteristic consistency is good, and the voltage division ratio error band range is small.

[0057] (2) The outer surface of the nano-gold alloy and high-quality silicon steel sheet of the utility model is provided with a copper braided belt and a semi-conductive crepe paper double shielding technology, which makes the product have very good stability in performance. When the temperature and current change, its ratio error and phase error remain completely unchanged.

[0058] 3. High insulation level: Organic potting glue is used as the insulation body of the sensor. There will be no breakdown during operation, and the insulation strength between resistor poles is very high.

[0059] 4. No "charge trap": It can solve a series of problems caused by retained charge in the transient process of the power grid.

[0060] 5. Phase current and zero-sequence current can be measured simultaneously.

[0061] 6. Can be used to measure harmonics.

[0062] 7. The material cost and manufacturing cost are low, more than 20% lower than the traditional electromagnetic current transformer.

[0063] 8. Low operation and maintenance costs, and can avoid problems such as the lifespan of electronic components in conventional electromagnetic transformers not reaching 20 years.

[0064] The three-phase current sensor of the present utility model is fully sealed and fully insulated, and can be integrally designed with an explosion-proof circuit breaker switching mechanism, a voltage sensor, a power-taking capacitor, and an intelligent measurement and control terminal to realize information collection and remote control.

[0065] It should be understood that the above specific embodiments of the present invention are only used for exemplary illustration or explanation of the principle of the present invention, and do not constitute a limitation to the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A three-phase current sensor for a maintenance-free intelligent explosion-proof circuit breaker, characterized in that, Comprising: A housing; A phase sequence coil, disposed inside the housing; A zero sequence coil, disposed inside the housing; An organic potting compound, filled between the phase sequence coil, the zero sequence coil and the housing; A non-inductive resistor, disposed at the side wall inside the housing, and connected in parallel to the secondary outlet end of the current coil.

2. The three-phase current sensor of the maintenance-free intelligent explosion-proof circuit breaker according to claim 1, characterized in that, The secondary outlet of the current sensor uses a mining flame-retardant shielded five-core cable.

3. The three-phase current sensor of the maintenance-free intelligent explosion-proof circuit breaker according to claim 2, characterized in that, The inner core of the mining flame-retardant shielded five-core cable is oxygen-free copper, and the outer insulation material is polyurethane.

4. The three-phase current sensor of the maintenance-free intelligent explosion-proof circuit breaker according to claim 1, characterized in that, The material of the housing is flame-retardant ABS composite engineering plastic.

5. The three-phase current sensor of the maintenance-free intelligent explosion-proof circuit breaker according to claim 1, wherein, The material of the phase sequence coil is nano gold alloy and high-quality silicon steel sheet.

6. The three-phase current sensor of the maintenance-free intelligent explosion-proof circuit breaker according to claim 1, characterized in that, The zero sequence coil adopts the principle of three-phase current magnetic potential synthesis.

7. The three-phase current sensor of the maintenance-free intelligent explosion-proof circuit breaker according to claim 6, characterized in that, The material of the iron core in the zero sequence coil is permalloy.

8. The three-phase current sensor of the maintenance-free intelligent explosion-proof circuit breaker according to claim 1, characterized in that, The outer surfaces of the phase sequence coil and the zero sequence coil are both wrapped with copper braid and semi-conductive corrugated paper.

9. The three-phase current sensor of the maintenance-free intelligent explosion-proof circuit breaker according to claim 1, characterized in that, The number of the phase sequence coils is 3, and the number of the zero sequence coils is 3.

10. A maintenance-free intelligent explosion-proof circuit breaker, characterized in that, Comprising a three-phase current sensor according to any one of claims 1 to 9.

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