Electromagnetic Current Transformers

The primary voltage and current in power systems are very high, and the rated operating parameters vary widely. Instruments and protection devices used for measuring and controlling the primary system cannot be directly connected to it. The high current requirement of the primary system necessitates the use of current transformers for isolation, enabling secondary relay protection, automatic devices, and measuring instruments to safely and accurately obtain current information from the primary electrical circuit. Current transformers are mainly divided into electromagnetic current transformers and electronic current transformers. Today, Dingbo Power Generator Manufacturer will focus on introducing electromagnetic current transformers.

1.Working Principle of Current Transformers

The structure of a current transformer is relatively simple. It consists of a primary winding, a secondary winding, an iron core, a frame, a housing, terminals, etc.

It is made based on the principle of electromagnetic induction. A current transformer is composed of a closed iron core. Its primary winding has a very small number of turns, so a small amount of current passes through it. The secondary winding has a large number of turns and is connected in series with the measuring and protection circuits. During operation, the secondary circuit is always closed, so the impedance of the series coil of the measuring instrument and protection circuit is very small, and the operating state of the current transformer is close to a short circuit.

2.Functions of Current Transformers

The first function is for measurement, often used in billing or measuring the current of equipment in operation. When measuring large alternating currents, in order to facilitate instrument measurement and reduce the danger of directly measuring high-voltage electricity, it is often necessary to use current transformers to convert them into more consistent currents. In this case, the current transformer plays the role of a converter and electrical isolation. The current transformer converts high current into low current in proportion as needed. For measurement, the primary side of the current transformer is connected to the primary system, and the secondary side is connected to measuring instruments or relay protection devices, etc.

The second function is for protection, often used in conjunction with relay devices. When a fault such as a short circuit or overload occurs in the line, the current transformer sends a signal to the relay device to cut off the faulty circuit, thereby achieving the purpose of protecting the safety of the power supply system. Current transformers used for protection are different from those used for measurement. They are used when the current is several times or dozens of times larger than the normal current. They require reliable insulation, high limit coefficients, good thermal stability, and good dynamic stability.

Dingbo Power was founded in 1974 and is one of the earliest manufacturers of generators and diesel generator sets in China. If you want get more information, please feel free to send email to [email protected] we will pay highly attention on your question.