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What is Current Transformer?

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Today, the use of devices at the right voltage is an issue that users need to keep in mind. Current transformers are designed to change the amperage as desired. Please learn more about the characteristics of current transformers in the following article.

What is Current Transformer?

Is a type of voltage transformer commonly used to reduce an alternating current (AC). It produces a current in its secondary coil proportional to the current passing through it.

Structure of Current Transformers

Current transformers consist of the following main parts:

  • Primary Current
  • Secondary Winding
  • Hollow Core
  • Ammeter

Principle of operation of Current Transformers

Based on the phenomenon of electromagnetic induction. When alternating current flows through a wire, around it will appear an electric field, this field will induce on the coil and an electric current will appear in it. This ratio of current is based on the number of turns of the winding in a variable current winding.

Classification of Current Transformers

Classification by structure:

+ Wound Current Transformer: For the primary winding of the current transformer, it will be connected directly to the conductors to help measure the current flowing in the circuit. Usually the current in the secondary winding will depend entirely on the winding ratio of the current transformer.

+ Toroidal Current Transformer: The primary winding of the current transformer will be connected directly to the conductors to measure the current flowing in the circuit. The amperage in the ring current transformer will not be composed of the primary winding. Instead, the current flowing in the circuit will be transmitted and run straight through the secondary slot or winding hole depending on the winding ratio of the current transformer.

+ Bar-type Current Transformer: This type of current transformer uses the actual cable or bus-bar of the main circuit as the primary winding, which is equivalent to a single turn. They are fully insulated from the high operating voltage of the system and are usually bolted to the current carrying device.

Classification by voltage used: Low voltage current transformer, medium voltage current transformer, high voltage current transformer.

How to read the current value 5A?

Most electrical cabinets use mechanical watches that can read the value of 5A. Today with increasing demand, we need to transmit this 5A signal to the PLC or other devices for monitoring and control. However, PLC and other control devices cannot read this 5A directly.
All control devices today come in standard 4-20mA or 0-10V format because we have to use a 5A value converter (10A, 20A, …) to Analog format 4- 20mA (0-10V, …)

Application of current transformers

Current transformers are an indispensable device in power monitoring and measurement systems. In simple terms, a current transformer is an electrical device used to convert high-value current to standard 5A and 1A currents. To provide safe voltage for circuit measurement, control and protection.
In addition to the classical current transformer that works on the principle of electromagnetism, there are now new current transformers for ultra-high voltage grids to reduce the cost of insulation of classical current transformers.
There are a wide range of current measurement and measurement equipment, such as wattmeter, power factor meter, power meter, protection relays or examples. release coils in magnetic circuit breakers …

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