The Research And Design On Sensor Head Of Electronic Current Transducer

With the continuous improvement of transmission capacity and voltage level in power system, the traditional electromagnetic current transformers have more and more weaknesses and have been difficult to meet the need that network develops towards automation and digitized direction. In recent years, the electronic current transformer(ECT) is studied extensively at home and abroad, become a revolutionary research. The paper focuses on the current sensor and solves the problem that electronic current transformer is difficult to measure low-current accurately.At first, the paper summarizes the significance of studying electronic current transformer, and analyses the situation of studying electronic current transformer at home and abroad. All kinds of current sensing head are studied, and their shortcomings are analysed. According to electromagnetic theory analysis, the paper proposes that spiral-tube hollow coil can be used as the current sensing head of ECT, and gives two types of spiral-tube hollow coils which are long straight spiral-tube hollow coil based on manual and planar spiral-tube hollow coil based on PCB. Their working principle and anti-interference mechanism of external magnetic fieldis are given. Their formulas for calculating the coil's coefficient of mutual inductance are derived. The various structures of spiral-tube hollow coil are reserched and explored with the practical engineering. The paper analyses the factors affecting its performance, and gives the corresponding solution. Experimental models are made and tested for experimental research. At last, the paper studies and explores ECT based on spiral-tube hollow coil for application technology in the high-voltage system, medium-voltage system and the low-voltage device, and proposes that the planar spiral-tube hollow coil based on PCB can be used as the future focus in research and application.Theoretical analysis and experimental results show that the current sensor based on spiral-tube hollow coil has great frequency bandwidth for measurement, fast response and strong ability of anti-electromagnetic interference, and can measure low-current accurately. It is suitable for a special current converter of electronic power meter and relay protection. Similarly, it is also suitable for high-current measurement in high-voltage and medium-voltage system. The technology has been the national patent. There are important theoretical significance and positive practical value for the development of new electronic current transformer.