Self-Powered Current Transformer

Recently, the Chinese Electrical Engineering Society organized from the electric power, optical and other fields of experts, China's first "highly reliable and independent fiber optic current transformer" for technical appraisal. Chen Weijiang, academician of the Chinese Academy of Sciences, as the representative of the industry experts agreed that the project to form a full range of optical current transformer equipment, representing the field of the highest international level of technology, to realize the field of science and technology in the field of self-reliance and innovation beyond the important significance. 　　For a long time, fiber optic current transformer and its core optoelectronic devices are mainly dependent on imports, and because of its face of extreme low temperature, external vibration, strong electromagnetic interference and other complex and harsh operating environment, the failure rate remains high, many times leading to DC blocking and stopping, and has become a constraint on the reliable operation of DC engineering problems. 　　State Grid Corporation, deputy director of the equipment department Guo Xianshan said, "fiber optic current transformer oil-free, gas-free, safe and environmentally friendly, fast response speed, dynamic range, has become the main direction of development of the current measurement in the power system, especially in the DC power transmission project has an irreplaceable role, and its reliability directly affects the safe and stable operation of the system. " 　　In response to the current situation of operational failures in recent years, the Chinese Academy of Electric Sciences, State Grid Jiangsu Electric Power Company composed of a team after more than ten years of technical research, breakthroughs in fiber-optic current transformer polarization optics analysis method and disturbance mechanism, wave piece integrated sensing fiber development process, the core of the reliability of optoelectronic devices to grow the test method, the operational status of intelligent monitoring and early warning technology and other core problems. Finally, successfully developed the first 100% fully localized high reliability independent fiber optic current transformer, temperature, vibration resistance and other key indicators of environmental weathering and reliability of the comprehensive improvement, and ± 800kV Qingnan converter station successfully network operation, marking China's complete solution to the field of optical current measurement of the "neck" The project team has accumulated a lot of experience in this process. In the process, the project team has published 19 standards, 46 invention patents, 49 papers and monographs, and 17 software copyrights.   Learn more :  https://www.hemeielectricpower.com/

November 20, this reporter learned from the Chinese Academy of Electric Sciences Wuhan Branch was informed that after two years of technological research, the hospital successfully developed a low-voltage current transformer (i.e., CT) full-range calibration equipment under charged conditions, for the first time with a non-stop state of the low-voltage current transformer to carry out the periodic calibration capacity. At present, the device has been in the State Grid Shanghai Electric Power Company and other units of the pilot application, the follow-up will be carried out in many parts of the country to carry out network operation work. Energized calibration is one of the most widely used techniques in energized operation, capable of accurately diagnosing faulty equipment and effectively detecting operational safety hazards. Previously, the commonly used method was the traditional detection technology relying on power outages, and the time window for power outage detection is difficult to coordinate, which is not conducive to the business environment and power supply reliability; in addition, the use of banding detection means can only detect the error situation of the user's current load point, and can not comprehensively reflect the user's operation process of all the actual error, the accuracy is difficult to ensure. As a measuring instrument, the transformer full-range energized calibration equipment can measure the amplitude and phase errors of the operating low-voltage current transformers in full range in accordance with the national calibration regulations. The technology adopts electromagnetic induction to calibrate the signal coupling and injection of low-voltage CT, without the need to make electrical connection to the running power supply line, and without adding any auxiliary device or module to the original power supply line, which makes the operation process simple and can effectively guarantee the safety of the personnel and the operation of the power grid. Wuhan Branch of the Chinese Academy of Electric Sciences charged calibration research team leader, professor-level senior engineer Zhang Jun told reporters that, in this case, the development of a can be carried out with electricity, high accuracy and high correlation with the traditional volume of transmission system there is a high degree of correlation between the transformer error calibration technology, appears to be very urgent. Since 2022, under the support of the State Grid Corporation, the Chinese Academy of Electric Sciences and the State Grid Shanghai Electric Power Company set up a project team, relying on the national high-voltage metering station, to jointly carry out the "low-voltage CT full-range calibration under electrified conditions" technology research. The research team through the field demand collection, the overall design of the system program, laboratory development and testing, project site debugging, prototype production and other aspects, repeated attempts, continued research, and the results will be completed on the grid pilot, and achieved good results. According to reports, low-voltage CT charged full-range calibration technology successfully implemented, can realize the normalization of low-voltage CT full-range charged calibration business, to ensure the stability of low-voltage CT metering performance, to avoid the user and the State Grid Corporation's power measurement losses. At the same time, it can improve the technical means of measurement and calibration of transformers, without affecting the quality of power supply services, and effectively improve the level of supervision and control of low-voltage CT operation quality.   Learn more :  https://www.hemeielectricpower.com/

Current transformer is an important secondary device in the power system, widely used in metering, measurement, relay protection and other secondary circuits, in the high current or high voltage occasions we can not directly use the ammeter to measure the current size of the circuit, only through the secondary side of the current transformer to measure, so that it will be safe, then for the parameters of the current transformer, the 0.5 level, 1.0 level, as well as 10P20, 5P20 what does it mean? How do we choose to use it? The following will be carefully explained: 　　First, the principle of the current transformer 　　Current transformer and transformer is based on the principle of electromagnetic induction will be the primary side of the large current into the secondary side of the small current to measure the instrument. Current transformer is composed of a closed core and winding. The primary winding has a small number of turns and is strung in the line of the current to be measured. The secondary side of the winding turns is more, series in the measuring instrument and protection circuit, the current transformer in operation, its secondary side of the circuit is always closed, so the measuring instrument and protection circuit series coil impedance is very small, the current transformer's operating condition is close to a short circuit. 　　Types of current transformers 　　According to the use can be divided into: 　　Measuring current transformer: settlement of electricity costs 　　Measurement current transformer: measuring current, calculate the degree of electricity, etc., the accuracy is generally lower than the machine with two transformers, not as a settlement. 　　Protection current transformer: current speed protection, overcurrent protection, overload protection, etc.; 　　1. calibration current transformer accuracy: 0.1S level. Tolerance of 0.1%, commonly used in calibration measurement level current transformer accuracy.  　　2. measurement of current transformer accuracy: 0.2S 0.5 level. Tolerance of 0.2% and 0.5%, used for electricity billing basis, some occasions will also use the 0.5-level 　　3. Measuring current transformers: 0.5, 1.0, 2.0, etc., generally used for ammeters. 　　4. Protection of current transformer accuracy: 10P10, 10P20, 5P10, 5P20, etc., the meaning of accuracy: 10P10, for example, that is, the current flowing through the current transformer, is within 10 times its rated current, the inductor error within ± 10%. 　　5. In some special occasions, there are more accurate current transformers, there are 0.005 level, 0.05 level, etc., the use of occasions less.   Learn more :  https://www.hemeielectricpower.com/

What Is an Energy Harvesting Current Transformer?   An energy harvesting current transformer (energy harvesting CT) is designed to convert energy from the magnetic field generated by a current-carrying conductor into electrical energy for compatible electronic devices. Unlike conventional measuring current transformers, which primarily provide current signals for measurement and protection, energy harvesting CTs are designed to supply power to equipment such as power line monitoring terminals, sensors, and communication devices.         How Does an Energy Harvesting CT Work?   An energy harvesting current transformer operates based on electromagnetic induction. When AC current flows through a conductor, it generates a changing magnetic field. The magnetic core collects and guides the magnetic flux, inducing voltage in the secondary winding. A power management circuit can then convert this output into a suitable power supply for connected equipment. The system typically consists of a magnetic core, secondary winding, power management circuit, and, when required, an energy storage component. The actual output power depends on the primary current, core material, winding design, operating frequency, and electrical load.   Main Applications of Energy Harvesting Current Transformers Energy harvesting CTs are suitable for various power monitoring applications.   1. Overhead Power Line Monitoring They can provide local power for compatible monitoring terminals, sensors, and communication equipment installed on overhead power lines. 2. Underground Cable Monitoring They can support monitoring devices in underground cable systems where installing a separate power supply may be inconvenient. 3. Power Distribution Cabinets Energy harvesting CTs can supply power to selected monitoring terminals and sensors used in distribution cabinets and ring main units. 4. Smart Grid Monitoring They can help power compatible electronic devices used for remote monitoring, fault detection, and power distribution management.           How to Select the Right Energy Harvesting CT   When selecting an energy harvesting current transformer, consider the following parameters: Primary current range: Minimum operating current, normal current, and maximum continuous current. Output requirements: Required voltage, power, and load current. Inner diameter: The size must match the conductor and installation space. Magnetic core material: Silicon steel, nanocrystalline materials, and other magnetic alloys offer different performance characteristics. Installation environment: Consider temperature, humidity, corrosion protection, insulation, and enclosure requirements. The transformer and its power management circuit should be evaluated together to ensure that the system can meet the actual load requirements.   Customized Energy Harvesting CT and Magnetic Core Solutions   Different applications require different dimensions, magnetic properties, winding configurations, and output performance. Customized designs can help meet specific electrical and installation requirements. Hemei Electronics provides current transformers and magnetic core solutions for power monitoring and related applications. Our products can be evaluated according to your project specifications and application needs.   Looking for an energy harvesting current transformer for your project?   Contact Hemei Electronics to discuss your required current range, output voltage, power consumption, and installation dimensions. Visit our website to explore our current transformer and magnetic core products.