Analysis of the working principle of current transformer
In modern power systems, current transformer (CT) is an important device widely used in current measurement and protection. It undertakes the dual mission of "amplifying the accuracy of power system information while reducing risks". For suppliers, a clear understanding of the working principle of current transformers not only helps to convey technical value to customers, but also lays the foundation for product optimization and application expansion.
1. What is a current transformer?
A current transformer is an electrical device used to convert high current into low current. Since direct measurement of high voltage and high current is not only dangerous but also inconvenient for accurate reading, it is necessary to use a current transformer to convert the high current on the primary side (original current) into a small current on the secondary side (measurement system) at a fixed ratio, generally 5A or 1A, for use by instruments, relay protection devices and other equipment.
2. Working mechanism based on the principle of electromagnetic induction
The working principle of current transformers is derived from the law of electromagnetic induction. Its basic structure consists of a primary winding, an iron core and a secondary winding:
Primary side (primary winding): usually only one turn, connected in series in the main circuit, directly carrying the system current.
Iron core: made of high magnetic permeability material, guides magnetic flux and forms a closed magnetic circuit.
Secondary side (secondary winding): multi-turn winding, inducing a secondary current proportional to the primary current.
When a high current passes through the primary side, an alternating magnetic flux is generated in the iron core, and according to Faraday's law of electromagnetic induction, a current is induced in the secondary winding. This current maintains a fixed ratio with the primary current, usually 100:5, 200:5, 1000:5, etc., to facilitate the subsequent instrument to accurately measure or protect the equipment.
Based on electromagnetic induction, current transformers convert high currents into safe and measurable low currents, and are key components to ensure safe, reliable, and efficient operation of power systems. For suppliers, a deep understanding of their working principles and application requirements will not only help optimize product design and improve accuracy, but also more accurately meet customers' supporting requirements in various scenarios such as industry, energy, and construction.
