.A current transformer (CT) is an electrical device that converts high primary current into low secondary current. It is mainly used for measuring instruments and relay protection devices to achieve monitoring, control, and protection of power systems. The working principle of a current transformer is based on the law of electromagnetic induction, which converts the current through a closed iron core and winding. .A current transformer consists of a closed iron core and winding. The number of turns in a winding is very small, and it is connected in series in the current line that needs to be measured, so all the current of the line often flows through; The secondary winding has a large number of turns and is connected in series with measuring instruments and protection circuits. During operation, the secondary circuit is always closed, and the impedance of the measuring instrument and protection circuit series coil is very small. The working state of the current transformer is close to a short circuit of 13. .Measurement instrument: Convert the high current of a primary system into low current, so that the measurement instrument can work safely and accurately. For example, in high-voltage power systems, the primary side current may reach thousands or even tens of thousands of amperes, which can be converted into standard 5A or 1A small currents through current transformers. .Relay protection device: When a fault occurs in the power system, the protection device needs to accurately reflect the changes in the primary side current in order to act in a timely manner. The current transformer maintains a certain output characteristic under high current, ensuring reliable operation of the relay protection device. .Type and Characteristics .Measurement current transformer: mainly used for measurement and measurement in power systems, requiring high accuracy and good stability. The accuracy level is usually divided into 0.1, 0.2, 0.5, 1.0, etc. The smaller the number, the higher the accuracy. .Protective current transformer: mainly used as a relay protection device in power systems, it is required to accurately reflect the changes in primary side current in case of faults. The protective current transformer has good saturation characteristics and anti-interference ability under fault current.
