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How does a Transformer Works for Electrical Industry?

Updated: Aug 20, 2021

A transformer is an electrical device that transmits alternating current from one circuit to another or multiple circuits at a constant frequency based on the principle of electromagnetic induction. The amount of electrical energy transmitted is determined by the power of the electrical appliance. It can increase or decrease the AC voltage. Transformers have a wide range of uses that can meet various needs. The strength of the voltage can be adjusted by the transformer to cope with various devices with different voltages. The shape design of the transformer is also divided into different sizes, but no matter its size, its purpose is the same.

The transformer is mainly composed of four parts: iron core, coil, input connection, and output connection.

Iron core

The iron core is usually made of ferromagnetic material. The main purpose is the magnetic flux generated in the transformer to provide a magnetic circuit and avoid the loss of electricity. Most iron cores are usually not solid steel rods but are made of laminated steel plates. This structure can avoid the elimination of energy loss and uniform heat dissipation. If it is a solid rod, it will produce eddy currents and lose a lot of energy. The iron core is mainly divided into two types: magnetic core type (windings surround the laminated iron core) and shell-type (windings are surrounded by the laminated iron core).


Coils are also called windings and can be divided into primary windings and secondary windings. The primary winding is mainly a winding that draws power from alternating current. The secondary winding is the coil that transfers the changed voltage to the load.

Input connection

The input connection is mainly the input side (primary side) of the transformer, which is used to change the original power supply.

Output connection

The input connection is the output side (secondary side) of the transformer, which is used to transfer power to the load.

The main operating principle of the transformer is that when an alternating current is applied to the primary winding, the alternating current will cause the coil to generate a magnetic field. The iron core of the transformer will transfer this alternating current to the secondary winding. When the magnetic field passes through the secondary winding, it will cause the electrons in it to move, thereby forming an induced electromotive force and generating an electric current. If the secondary winding is larger than the primary winding, it means that the output voltage of the transformer is greater than the input voltage, so it is called a "step-up transformer". On the contrary, when the secondary winding is smaller than the primary winding, the output voltage is smaller than the input voltage, which is a "step-down transformer".

Types of Transformer

According to the number of turns of the primary and secondary winding, it can be divided into the step-up transformer and step-down transformer two types.

The step-up transformer mainly converts the low voltage and large current value on the primary side into the high voltage and low current value on the secondary side. When the number of voltage turns of the secondary winding (output side) is greater than the number of voltage turns of the primary winding (input side), this is called a step-up transformer.

The step-down transformer converts the high voltage and low current values on the primary side of the transformer into low voltage and high current values on the secondary side of the transformer. When the number of turns of the secondary winding is less than the number of turns of the primary winding, the voltage on the output side is lower than the voltage on the input side.

According to the usage, it can be classified into three types: Power Transformer, Distribution Transformer, and Instrument Transformer.

Power Transformer:

Power transformers are mainly used in high-voltage transmission networks. It is often installed in power stations and transmission substations. The maximum efficiency can be exerted at a high load or close to full load. Large volume and good insulation.

Distribution Transformer:

Distribution transformers are mainly used to reduce the voltage in order to distribute power to users in the home or business field. It can be used to regulate voltage stations below 33KV. The primary coil of the distribution transformer is made of enameled copper wire or ordinary aluminum wire, and the secondary coil is made of thick aluminum and copper. This type of transformer has good voltage regulation efficiency.

Instrument Transformer:

An instrument transformer is a device used to convert voltage and current. It reduces the high voltage and large current on the primary side to a level that can be measured by conventional instruments to avoid damage to the secondary side. Instrument transformers can be categorized into Current Transformer and Potential Transformer.

  • Current Transformer:

The function of the current transformer is that when a large amount of current enters the transformer, it can convert the large current into the amount of current required by the circuit. This type of transformer has the effect of detection and protection.

  • Potential Transformer:

The function of the potential transformer is to reduce the voltage to a safe range. The primary winding of the transformer serves as a safe point and is connected to the high-voltage line of the measured voltage, while other measuring instruments are connected to the secondary side of the transformer.

According to the phrase, it can be classified into two types: Single-phase Transformer and Three-phase Transformer.

Single-phase Transformer:

A single-phase transformer is a static and fixed device. Its working principle is mainly to use Faraday's law of mutual inductance. Faraday's law of mutual inductance states that under constant frequency and voltage changes, this type of transformer will transfer alternating current from one circuit to another. The two windings of a single-phase transformer, the primary winding is used to provide AC power, and the secondary winding is used to connect the load.

Three-phase Transformer:

The three-phase transformer has six windings, three primary windings, and three secondary windings. In order to input different voltages, the input winding can use multiple windings to adapt to different input voltages. Each primary winding and secondary winding will have a star or delta configuration. In theory, a three-phase transformer is formed by connecting three single-phase transformers. This type of three-phase transformer is suitable for power generation and distribution in industrial applications.


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