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# We all know that a transformer is a device that changes voltage, so how does a transformer change voltage?

163.com | 22/04/2021

## Why can the transformer change the voltage level?

Let's first understand the structure of the transformer. Although there are many types of transformers and their sizes are quite different, their basic structure is similar. Both sets of coils are wound on the same iron core. These two sets of coils are called primary coils and secondary coils. Electric current goes in from the primary coil and flows out from the secondary coil. If the primary coil has more turns than the secondary coil, the voltage on the secondary coil will decrease, which is a step-down transformer; conversely, if the primary coil has fewer turns than the secondary coil, the voltage on the secondary coil will be Increase, this is the step-up transformer.

In fact, the working principle of the transformer is not complicated. According to the principle of electromagnetic induction, when a conductive object is in a changing magnetic field, a current can be induced in the conductor. When the transformer is connected to the AC grid, the current is input to the primary coil of the transformer, and at this time, a magnetic field will be generated around the current. As the current direction of the input alternating current changes continuously, a magnetic field that changes synchronously with the current will be generated, and the generated magnetic field will form a closed loop along the transformer core. As the size and direction of the magnetic field are constantly changing, a current is induced in the secondary coil. Because the voltage on each coil is equal, the more turns of the secondary coil, the higher the voltage output from the secondary coil. What if the direct current is input to the transformer? Since the current of the direct current is always in one direction, the direction of the generated magnetic field will not change, so no voltage will be induced on the secondary coil. Therefore, the transformer can only change the voltage of the alternating current.

Transformers mainly use the principle of electromagnetic induction to transfer electrical energy or signals from one circuit to another, or as an important component of signal transmission. When there is an alternating current in the primary coil, alternating magnetic flux is generated in the iron core (or magnetic core), causing a voltage (or current) to be induced in the secondary coil. The transformer is composed of iron core (or magnetic core) and coil. The coil has two or more windings. The winding connected to the power supply is called the primary winding, and the remaining windings are called the secondary winding.

Changing the ratio of the turns of the two coils will result in a different voltage in the second coil L. The transformer is a device that transforms AC voltage, current and impedance based on this principle. The number of turns of the primary coil and the secondary coil With an appropriate ratio, the voltage in the circuit can be increased or decreased. It can be expressed by a formula, namely:

## Primary voltage (U1)/secondary voltage (U2) = number of primary turns (n1)/number of secondary turns (n2)

It should be noted that any transformer can only transfer electric energy from the primary to the secondary. It can increase or decrease the voltage, but cannot increase the power. The ratio of the voltage between the primary and secondary of the transformer is equal to the ratio of the secondary and primary currents. Without considering the loss of the transformer, it can be said that the power input by the primary is equal to the power output by the secondary.

Transformer is a static electrical device. It is a device that converts a certain level of AC voltage and current into another level of voltage and current at the same frequency based on the principle of electromagnetic induction. Function: transform AC voltage, exchange AC current and transform impedance.

Basic principle: A simple single-phase transformer consists of two conductors. When a certain amount of current (such as alternating current or pulsed direct current) passes through one of the conductors, it will produce a fluctuating magnetic field. According to the principle of electromagnetic mutual inductance, this changing magnetic field will cause the second conductor to generate a potential difference. If the second conductor is part of a closed circuit, then the closed circuit will generate current. Electricity is then transmitted.

In general transformers, the relevant conductor is a coil composed of (mostly copper) wires, because the magnetic field generated by the coil is much larger than that of a straight wire.

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