Electrical CT meter: the core component of current measurement

In complex power systems, current measurement and monitoring are important links to ensure stable operation of the system and timely detection and solution of problems. As a key device in this link, the electrical CT (current transformer) meter has an irreplaceable position in the power industry with its unique design and excellent performance. This article will take "Electrical CT meters usually have closed cores and windings, and their primary windings have fewer turns and are connected in series in the circuit of the current to be measured; the secondary windings have more turns and are connected in series in the measuring instrument and protection circuit" as the theme to deeply explore the structural characteristics, working principles and applications of electrical CT meters in power systems.

Structural characteristics of electrical CT meters
The core of the electrical CT meter lies in its unique structural design, which mainly includes closed cores and windings. As the main channel of magnetic flux, the core has the characteristics of high magnetic permeability and can effectively transmit and concentrate magnetic flux. The windings are divided into primary windings and secondary windings, which have different functions.

The primary winding has fewer turns and is directly connected in series in the circuit of the current to be measured. This design enables the primary winding to directly sense the current changes in the line and convert them into changes in magnetic flux. Since the primary winding has a small number of turns, its resistance and inductance are relatively small, and the impact on the line is minimal.

The secondary winding has a large number of turns and is usually connected in series in the measuring instrument and protection circuit. This design enables the secondary winding to sense the changes in magnetic flux generated by the primary winding and generate a secondary current proportional to the primary current. Since the secondary winding has a large number of turns, the secondary current it generates is relatively large, which is convenient for the use of measurement and protection devices.

Working principle of electrical CT meter
The working principle of electrical CT meter is based on the law of electromagnetic induction. When current flows through the primary winding, an alternating magnetic flux is generated in the iron core. This magnetic flux passes through the secondary winding, thereby inducing an electromotive force in the secondary winding. Since the secondary winding has a large number of turns, the induced electromotive force is also relatively large. When the secondary winding is closed, a secondary current is formed, which is proportional to the primary current, thereby realizing the conversion and measurement of current.

Application of electrical CT meter in power system
electrical CT meter is widely used in power system. They are used in various occasions where current measurement is required, such as generators, transformers, transmission lines, busbars, etc. Through electrical CT meters, the power system can monitor the current conditions in each line in real time, providing important data support for the system's dispatching, control, protection, etc.

In terms of protection, the electrical CT meter is used in conjunction with the relay protection device to achieve fast and accurate protection of the power system. When a system fault occurs, the electrical CT meter can quickly sense the change in current and transmit this information to the relay protection device. The relay protection device determines whether it is necessary to act to cut off the faulty part according to the preset protection logic and set value, thereby protecting the safe and stable operation of the system.

In addition, electrical CT meters are also widely used in the field of power metering. By accurately measuring the magnitude and phase of the current, accurate metering and billing of electric energy can be achieved. This is of great significance for maintaining the fairness, justice and orderly operation of the power market.

With its unique structural design and excellent performance characteristics, electrical CT meters play an irreplaceable role in the power system. They not only provide important data support for the dispatching, control, protection, etc. of the power system, but also promote the fairness, justice and orderly operation of the power market. With the continuous development of electric power technology, the performance and application scope of electrical CT meters will continue to expand and improve.