Split core currrent transformer

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/