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A current sensor is a detection device that detects current information, converts it into electrical signals that meet certain standards or other signals that can be analyzed, and performs operations such as transmitting, storing, and displaying these signals.   Current measurement can meet current monitoring, control, analysis and other requirements. For example, during the use of power supply, it is necessary to monitor the current, activate automatic protection devices in time when overcurrent, overvoltage, etc. occur, or help realize intelligent control to avoid equipment damage. In addition, current monitoring is equally important during the power supply technology upgrade process. Therefore, power supply technology using current sensors has gradually become a development trend.   Current sensors generally have the characteristics of high sensitivity, high temperature stability, strong anti-interference, and low power consumption. They can realize power measurement and current control, thereby monitoring energy systems and protecting power systems. According to different principles, current sensors can be divided into several categories such as electromagnetic current transformers, electronic current transformers, and fiber optic current sensors. Among them, the electronic current transformer sub-product Hall current sensor is the mainstream of the market, with demand accounting for than more than 50%.   Current sensors can be widely used in electronics, home appliances, new energy vehicles, new energy power generation, smart grids, industrial equipment, medical equipment and other fields. Among them, in the field of new energy vehicles, current sensors are indispensable and are widely used in battery management systems BMS, current distribution units PDU, motor controllers, on-board chargers OBC, DCDC converters, charging piles, etc.; in the field of medical equipment , many devices need to accurately control the current passing through the device to ensure patient safety and device safety, and high-precision current sensors are required.   According to the "2023-2028 China Current Sensor Industry Market In-depth Research and Development Prospects Forecast Report", with the continuous expansion of application fields and the continuous advancement of downstream industry technology, the performance of current sensors continues to upgrade, and the market development space continues to increase. In 2022, the global current sensor market will be approximately 18.9 billion yuan; it is expected that the global current sensor market will grow at a compound annual growth rate of approximately 8.1% from 2022 to 2028, and the market size will reach 30.2 billion yuan by 2028.   Industry analysts said that after continuous development, the number of current sensor manufacturers in my country is increasing. However, my country still has deficiencies in the development of high-precision current sensors, and there is still room for greater progress in the industry in the future.   Read more:  https://www.hemeielectricpower.com/

The zero-sequence current transformer is an important instrument in the power system and is used to measure the zero-sequence current in the power system. The power system is composed of three phases, namely A, B, and C. Each phase can operate independently. However, in power systems, there is a current called zero sequence current that exists in three phases simultaneously. With zero-sequence current transformers, we can measure this current to ensure proper operation of the power system. The difference between a current transformer and a zero-sequence current transformer is the type of current measured. Typically, current transformers are used to measure on-load current or load current, while zero-sequence current transformers are used to measure zero-sequence currents in power systems. Therefore, the zero-sequence current transformer needs to have special structure and measurement capabilities to ensure accurate measurement of the zero-sequence current. current transformer power supply split core current transformer current transformer coils   1. Zero sequence current In power systems, there is a current called zero sequence current that exists in three phases simultaneously. Zero sequence current is caused by various factors and should not exist as it may cause system failure or equipment damage. In power systems, the importance of measuring and monitoring zero-sequence currents is self-evident. To clearly understand zero sequence current, let us look at the basics of the system. The power system consists of three phases, including phase A, phase B and phase C. Under normal conditions, these phases should have equal voltages and currents, resulting in a balanced system. However, under certain circumstances, such as faults or unbalanced loads, zero-sequence currents may occur in the power system. Zero-sequence currents are caused by unpaired charges, which can be any number of charges scattered throughout the system or present in ungrounded equipment or cables. If there are unpaired charges or ungrounded devices in the system, current imbalances and zero-sequence currents can result.   2. Working principle of zero sequence current transformer The main function of the zero-sequence current transformer is to measure the zero-sequence current in the power system and output the corresponding electrical signal. Its working principle is very simple: when a current flows in the cable through the transformer, the transformer generates a magnetic field proportional to the current. This magnetic field is then passed to a current sensor and generates a corresponding current signal.   3. Application of zero sequence current transformer Zero sequence current transformers have many applications including: 1. Power system protection: In the power system, zero sequence current can be used as a fault indicator to detect and protect equipment in the power system. 2. Power quality monitoring: Zero sequence current can be used to monitor the quality of the power system and indicate problems and faults in the power system. 3. Ground fault detection: Ground fault is a common fault type in power systems. By using zero-sequence current transformers, fault conditions present in equipment that are not paired with charges or are not grounded can be detected.   4. Conclusion In short, the zero-sequence current transformer is an important measuring device in the power system and is used to detect the zero-sequence current in the power system. Unlike current transformers, zero-sequence current transformers require special structure and measurement capabilities to ensure accurate measurement of zero-sequence current. Zero-sequence current transformers can be used in power system protection, power quality monitoring, ground fault detection and other fields, and play a very important role in the power system.   Read more:  https://www.hemeielectricpower.com/

Relay protection generally consists of three parts: measurement part, logic part and execution part. The function of the measurement part is to measure the physical quantity of the working state of the protected component and compare it with the given setting value to determine whether the protection should be activated. The function of the logic part is to make the protection device work according to a certain logic program based on the size, nature, order of appearance, etc. of each output of the measurement part, and finally pass it to the execution part. The function of the execution part is to complete the task of the protection device according to the signal sent by the logic part. Such as sending a signal, tripping or not acting, etc. Classification of relay protection 1) Classification according to the protected objects: transmission line protection, generator protection, transformer protection, busbar protection, motor protection, etc. 2) Classification according to protection principles: current protection, voltage protection, distance protection, differential protection, direction protection, zero sequence protection, etc. 3) Classification according to the type of faults reflected by the protection: phase-to-phase short-circuit protection, ground short-circuit protection, inter-turn short-circuit protection, disconnection protection, out-of-step protection, loss of excitation protection and over-excitation protection, etc. 4) Classification according to the implementation technology of relay protection devices: electromechanical protection, rectifier protection, transistor protection, integrated circuit protection, and microcomputer protection. 5) Classification of the relationship between relay protection measured value and set value: over-protection (measured value > set value), under-protection (measured value > set value) 6) Classification according to the role of protection: main protection, backup protection, auxiliary protection, etc. Main protection: protection that reflects the fault of the protected component itself and removes the fault in the shortest possible time. Backup protection: Protection used to remove faults when the main protection or circuit breaker refuses to operate. It is further divided into near backup protection and far backup protection. Near backup protection: Install two sets of protection at this component. When the main protection refuses to operate, the other set of protection of this component will act. Remote backup protection: When the main protection or circuit breaker refuses to operate, the backup protection is implemented by the protection of adjacent power equipment or lines.   Principle analysis of relay protection devices Relay protection devices include a measurement part (and a fixed value adjustment part), a logic part, and an execution part. 1. Sampling unit It electrically isolates the physical quantities (parameters) in the operation of the protected power system and converts them into signals that can be accepted by the comparison and identification unit in the relay protection device. It is composed of one or several sensors such as current and voltage transformers. 2. Comparative identification unit Including a given unit, the signal from the sampling unit is compared with the given signal to determine what signal the next-level processing unit sends out. (Normal state, abnormal state or fault state) The comparison and identification unit can be composed of 4 current relays, two of which are quick-break protection and the other two are over-current protection. The setting value of the current relay is the given unit. The current coil of the current relay receives the current signal from the sampling unit (current transformer). When the current signal reaches the current setting value, the current relay acts and passes to the next level through its contacts. The processing unit sends a signal that causes the circuit breaker to eventually trip; if the current signal is less than the set value, the current relay does not act, and the signal transmitted to the downstream unit does not act. The information of "quick break" and "over current" of the identification and comparison signal is sent to the next unit for processing. 3. Processing unit It accepts the signal from the comparison and identification unit, processes it according to the requirements of the comparison and identification unit, and determines whether the protection device should act according to the size, nature, and order of combinations of the outputs of the comparison link; it is composed of time relays, intermediate relays, etc. . Current protection: quick break---intermediate relay action, overcurrent, time relay action. 4. Execution unit Fault handling is implemented through execution units. Execution units are generally divided into two categories: one is a sound and light signal relay; (such as an electric whistle, an electric bell, a flashing signal light, etc.) and the other is the opening coil of the operating mechanism of the circuit breaker to open the circuit breaker. 5. Control and operating power supply The relay protection device requires its own independent AC or DC power supply, and the power of the power supply increases or decreases depending on the number of devices controlled; the AC voltage is generally 220V or 110V.   Read more:  https://www.hemeielectricpower.com/

Compared with traditional silicon steel, iron-based amorphous alloys have the advantages of high saturation magnetization, low iron loss and low coercive force, making them an ideal choice for soft magnetic materials. Iron-based amorphous alloys have attracted the attention of many researchers due to their excellent mechanical strength, high thermal stability and corrosion resistance. At present, iron-based amorphous alloys have been widely used in fields such as marine engineering and power electronics. However, with the deepening of engineering applications, further optimizing the amorphous formation ability and soft magnetic properties of iron-based alloys has become one of the main research directions. Heavy rare earth elements Gd and Dy can reduce the Curie temperature of iron-based metallic glass, increase magnetic entropy change and refrigeration capacity, and are suitable for the production of low-cost magnetic refrigeration materials. Of course, the addition of rare earth elements will also affect the amorphous oxidation performance. Rare earths have a strong affinity for oxygen and are therefore easily oxidized, which limits their applications. Studying the oxidation mechanism of rare earth-containing amorphous alloys plays an important guiding role in expanding their application scope. Wei Bingbo and others from Northwestern Polytechnical University improved the amorphous formation ability of the ternary Fe73B22Nb5 alloy by adding Gd element. The effect of Gd element content on the thermal stability and room temperature magnetic properties of the alloy was clarified, and the mechanism of rare earth elements in the alloy oxidation process was systematically revealed, providing an optimization solution for the composition design of iron-based amorphous alloys. Relevant research results will be published online in Acta Physica Sinica in March 2024.   This work was funded by the National Key Research and Development Program, the National Natural Science Foundation and the Shaanxi Provincial Natural Science Foundation. Read more:  https://www.hemeielectricpower.com/

Currently, the most widely used power supply method is solar power supply, but this method is greatly affected by climate conditions and lacks long-term maintenance-free capabilities. Laser power supplies have been used in electronic current transformers and active optical current transformers, but this type of power supply is not suitable for field work. A more promising power supply method is to extract electric energy from overhead transmission lines, place an energy coil on the line, and convert the energy of the line to the secondary side to achieve isolated power supply. Power equipment installed on the high-voltage side of high-voltage transmission lines: conductor temperature, breeze vibration, secondary pitch oscillation tension, ice coating monitoring device, etc. of high-voltage overhead transmission lines. Power equipment that is difficult to obtain power near high-voltage transmission lines: various monitoring equipment on underground power cable lines, monitoring equipment in ring main units, etc. energy harvesting current transformer current transformer coils switch mode power supply - Performance characteristics: Induction energy harvesting, stable and safe, maintenance-free Open energy harvesting transformer, easy to install and simple to wire. The energy harvesting module is packaged with metal shielding, which has good sealing performance, adapts to harsh environments, and operates stably. Able to maintain stable output despite changes in line current. Adopts switching voltage stabilization standard design. The output voltage is stable and the ripple is small. The output power can reach more than 300W Can work continuously under 3000A current Can be installed on transmission lines with any voltage level from 6kV to 500kV. The battery pack is optional to maintain normal use during power outages. Working principles: The energy harvesting device of the transmission line consists of an energy harvesting transformer and an energy harvesting power module.   Read more:  https://www.hemeielectricpower.com/

Current induction power supply, also known as CT power supply or current transformer power supply, draws power from the magnetic field induced by wires. The isolation transformation of the power supply mainly relies on the principle of electromagnetic induction, and can perform both voltage conversion and current conversion; At present, various types of power conversion are mainly based on voltage conversion, from high-voltage power generation and transmission to low-voltage conversion inside electrical appliances. Their basic structures are derived from the voltage conversion mode (such as PT voltage transformer, etc.). energy harvesting current transformer split core power supply CT power supply CT permalloy core   The current induction power supply is different from common power supplies. Its theoretical basis is based on the current transformation of the electromagnetic induction principle. The premise of its energy transformation is that the primary side (often the transmission wire) has sufficient AC current transmission, and no matter how the wire current fluctuates , the power output must remain stable. The current transformer commonly used in the power industry can be regarded as a typical application for drawing power from the power supply.   Read more:  https://www.hemeielectricpower.com/

A detection device used to indicate the occurrence of short-circuit faults and ground faults in distribution lines in a power distribution system and to indicate the phase of faults. According to the use can be divided into cable and overhead type. The main role of the fault indicator in the distribution network automation is firstly to monitor the real-time operation status of the distribution network, and secondly to achieve rapid fault location and isolation in the event of grid faults, and to shorten the fault processing time. 　　This will shorten the outage time and improve the stability of power supply. The development of power distribution automation makes the fault indicator widely used. 　　Line fault indicator can be directly installed in the 6KV to 35KV voltage level line, through the scene flap, flash indication way to check the line grounding, short-circuit faults, line management personnel to find faults to provide technical support. 　　At present, generally provided by the solar cell to the battery charging, so worried about the rainy day power shortage, at the same time, large solar panels, when the wind swings, pit wind ability is poor.   　　Ideal way is through the current transformer induction to take power directly to the battery charging (for data collectors and other electronic devices to provide working power, for wireless telecommunication equipment to provide communication power, for the electric mechanism to provide driving power, and can be on the backup battery and energy storage capacitor charging. Due to the small size and easy installation, the current transformer inductive power supply has become a more dominant way of drawing power in the fault indicator system. Currently there are some difficulties in implementation, because the current is too variable, and the excess energy is not well released when the current is high. What is needed is a wide-range input CT energy harvesting circuit to realise micro-power high-voltage power taking. Power industry standard DL/TL1157-201 Technical conditions for distribution line fault indicators. (Requirements: the standby state of the line fault indicator of the whole machine operating current is not greater than 20UA). Adopted the power supply design combining power taking by line induction and battery standby, which solves the problem of short service life of the fault indicator in the market due to only relying on battery power supply.   Read more:  https://www.hemeielectricpower.com/

Switch Mode Power Supply (SMPS), also known as switching power supply and switching converter, is a high-frequency power conversion device and a type of power supply. Its function is to convert a level of voltage into the voltage or current required by the user through different forms of architecture. The input of a switching power supply is mostly AC power (such as mains) or DC power, and the output is mostly equipment that requires DC power, such as a personal computer, and the switch mode power supply converts the voltage and current between the two.   Switch mode power supplies are different from linear power supplies. Most of the switching transistors used by switch mode power supplies switch between fully open mode (saturation area) and fully closed mode (cutoff area). Both modes have the characteristics of low dissipation. The conversion will have higher dissipation, but the time is very short, so it saves energy and generates less waste heat. Ideally, the switching power supply itself consumes no power. Voltage regulation is achieved by adjusting the turn-on and turn-off times of transistors. On the contrary, when a linear power supply generates an output voltage, the transistor works in the amplification area and consumes power itself. The high conversion efficiency of the switch mode power supply is one of its major advantages, and because the switch mode power supply has a high operating frequency, it can use a small-sized, lightweight transformer. Therefore, the switch mode power supply will be smaller and lighter than a linear power supply. If high efficiency, size and weight of the power supply are important considerations, switch mode power supplies are better than linear power supplies. However, the switch mode power supply is more complicated, and the internal transistors will switch frequently. If the switching current is not processed, noise and electromagnetic interference may be generated that affects other equipment. Moreover, if the switch mode power supply is not specially designed, its power factor may not be high. There are two types of modern switch mode power supplies: one is DC switch mode power supply; the other is AC switch mode power supply. What is mainly introduced here is only the DC switch mode power supply. Its function is to convert the original power supply (coarse power) with poor power quality, such as mains power or battery power, into a higher quality DC voltage (fine power) that meets the requirements of the equipment. . The core of the DC switch mode power supply is the DC/DC converter. Therefore, the classification of DC switch mode power supplies relies on the classification of DC/DC converters. In other words, the classification of DC switch mode power supplies is basically the same as the classification of DC/DC converters. The classification of DC/DC converters is basically the classification of DC switch mode power supplies.   Learn more:  https://www.hemeielectricpower.com/

Isolation transformation of power supply mainly relies on the principle of electromagnetic induction for both voltage conversion and current conversion; at present, various types of power conversion are mainly voltage conversion, current induction power supply and people's common power supply is different, its theoretical basis stems from the electromagnetic induction principle of power conversion, the premise of its energy conversion is that the primary side (often the transmission conductor) has sufficient AC current transmission, and regardless of the Conductor current fluctuations, the power output should remain stable. 　　Therefore, the current-sensing power supply can not use conventional CT, plus a simple rectifier, voltage regulator circuit to obtain power. Use: Mainly used in power cable accessories, no DC power supply work site; energy harvesting CT starting current is small, energy harvesting CT with overcurrent protection device, can be used to install in the current range of larger cables, the output of a stable standard DC power supply. 　　General current transformer power take-off of the power supply is used in the way of capacitance (such as capacitors) energy storage, energy storage is relatively small (can be instantaneous high-power power supply to meet the current requirements of many high-voltage online monitoring systems and instrumentation power supply; a certain amount of power storage, line short-term blackout continue to be able to power supply), the current-sensing power supply (energy harvesting CT ) is the cable-type fault indicator communication terminals power supply is the ideal choice. Cost-effective and easy to install, taking into account the service life and the need for small maintenance workload, we recommend the use of super capacitors for energy storage components. energy harvesting current transformer switch mode power supply current transformer core   　　Current transformer taking power combined with battery storage power supply storage device is the battery, energy storage capacity is larger, a complete charging time is longer, for a few hours to a dozen hours ranging. After the charging is completed, it can protect the distribution automation terminal equipment for more than ten hours of power supply (the distribution automation terminal equipment can obtain normal working power through DC-DC converter). Intelligent ring network cabinet, ring network cabinet wireless temperature measurement system, high voltage overhead transmission line detection system is recommended to use capacitor or storage battery (lithium battery) as the energy storage element. 　　Current transformer power taking combined with battery energy storage power supply as shown in the figure, the circuit mainly includes power taking transformer, relay switch, rectifier bridge, energy storage battery and DC-DC converter part.   Read more： https://www.hemeielectricpower.com/

Current induction power supply, also known as CT power supply or current transformer power supply, draws power from the magnetic field induced by wires. The isolation transformation of the power supply mainly relies on the principle of electromagnetic induction, and can perform both voltage conversion and current conversion; At present, various types of power conversion are mainly based on voltage conversion, from high-voltage power generation and transmission to low-voltage conversion inside electrical appliances. Their basic structures are derived from the voltage conversion mode (such as PT voltage transformer, etc.). The current induction power supply is different from common power supplies. Its theoretical basis is based on the current transformation of the electromagnetic induction principle. The premise of its energy transformation is that the primary side (often the transmission wire) has sufficient AC current transmission, and no matter how the wire current fluctuates , the power output must remain stable. The current transformer commonly used in the power industry can be regarded as a typical application for drawing power from the power supply. In the power system, CT is the abbreviation of Curren Transformer, that is, current transformer.

The power supply current transformer(CT) is mainly used in the power line, can solve the equipment can not get other ways to power supply problems. 1) high-voltage transmission and distribution field: current induction power supply is mainly used for the lack of conventional power supply measures in the field of high-voltage transmission and distribution, in the transmission and distribution network, the voltage is as high as 10KV-1150KV, the working current of tens of amps to thousands of amps, although there is a huge transmission of electricity, many intelligent electronic equipment is lacking due to Although there is huge power transmission, many intelligent electronic equipments cannot be installed due to lack of electricity, or they have to be equipped with expensive and bulky solar or wind power generating equipments, which is like having no water to drink by the Yangtze River. 2) Smart Grid: With the development of the Smart Grid, the demand for intelligent electronic equipments on primary high-voltage equipments (e.g., overhead transmission lines, cables, ring cabinets, etc.) is enhanced, and the applications of the current sensing power supply are becoming more and more widely used, including, but not limited to, power distribution automation, intelligent ring cabinets, overhead transmission lines and cables, and intelligent ring cabinets. The applications of current-sensing power supply are getting wider and wider, including but not limited to: power distribution automation, intelligent ring main unit, overhead transmission line and cable monitoring, high-voltage power-carrying maintenance tools, and other extended applications (such as field communication base station, high-voltage transmission line indicator, etc.), such as: power supply for intelligent switchgear cabinet, power supply for ring main unit, power supply for transmission and distribution detection, and special power supply for fault indicator, and so on.   Specific applications: power distribution automation (distribution line fault indicator), outdoor intelligent switchgear, power on-line detection system (high-voltage transmission monitoring, cable status monitoring), electric power wireless temperature measurement system, active electronic transformer, high-voltage power line operation tools, other high-voltage power line electronic equipment (such as high-voltage power line indicator, etc.).   Read more:  https://www.hemeielectricpower.com/

High-voltage induction power take-off device is a new type of induction power take-off device that uses the electromagnetic energy induced around high-voltage transmission lines to obtain electrical energy. This device converts the electromagnetic energy around the transmission line into electric energy, providing stable power supply for the electrical equipment installed in the vicinity. It can ensure the long-term stable power supply of the load equipment, and is suitable to be used as the power supply device for on-line testing, monitoring, inspection, anti-theft and other electrical equipments on the high-voltage transmission line. TLTP series of high-voltage induction power supply device is a split installation, consisting of split core energy harvesting currrent transformer (TLTP-CT) and induction power supply module (TLTP-PM) two parts, split core energy harvesting current transformer can be directly suspended in the transmission line, can also be installed in the cable trench, the induction power supply module can be integrated with the user's equipment design, common equipment chassis. This device is suitable for 10kV, 35kV, 110kV, 220kV, 500kV and other voltage levels of high-voltage transmission lines. Split high-voltage induction power taking device is mainly used to provide long-term stable power supply for outdoor power line online detection device, line equipment anti-theft device, high-voltage line filth online monitoring device and other power equipment. This device consists of energy extraction coil, energy extraction power control circuit, energy storage circuit, voltage regulator circuit, etc. The circuit composition is shown in the figure; split type current transformer power supply current transformer clamp on current transformer   According to the size of the current on the transmission line, the high-voltage induction power taking device has three working states: 1, the current on the transmission line is very small, not enough to make the circuit work, the device is in the un-started state, not on the load output voltage and power. 2, the current on the transmission line is large enough, or even very large: at this time, the power taking power control circuit to control the power to take energy, after the energy storage circuit is full of energy, the power obtained is equal to the power consumed by the load. Strictly limit the excess energy into the circuit, to protect the normal operation of the circuit. 3, the current on the transmission line can make the device start working, but the energy obtained is less than the power of the load: the circuit is in intermittent operation. At this time, the circuit to take the maximum efficiency of the energy, and charge the energy storage circuit, in the energy storage circuit to store full energy before the first not to the load output voltage and power, when the energy storage circuit to store full energy, and then to the load power supply. Note: When designing and selecting or purchasing, be sure to clarify the following parameters: 1. High-voltage induction power device power requirements, that is, the maximum power consumption of user equipment. 2. The rated output voltage requirements. 3. The diameter of the transmission line, the line of normal operating current range and the maximum operating current. 4. Installation requirements: indoor, outdoor installation, hanging, placing installation. 5. Power supply interface or power output cable length requirements. 6.If you need to configure lithium battery pack, please specify the optional battery capacity (ampere-hour).   Read more:  https://www.hemeielectricpower.com/