how do power transformers work

Power transformer is a device that uses the principle of electromagnetic induction to change the AC voltage and transmit electrical energy. Its main components include the primary coil, secondary coil and iron core (magnetic core).(click to know what is inside a transformer )

When alternating current passes through the primary coil, an alternating magnetic field is generated, which passes through the core and causes an induced electromotive force in the secondary coil. By adjusting the turns ratio of the coil, the voltage can be increased or decreased.

Specifically, if the number of turns of the primary coil is more than that of the secondary coil, then the output voltage will be lower than the input voltage to achieve a step-down transformation; conversely, if the number of turns of the primary coil is less than that of the secondary coil, then the output voltage will be higher than the input voltage to achieve a step-up transformation. At the same time, the transformer can also achieve the transformation of current and impedance transformation.

In addition, power transformers play a role in stabilising the voltage in the power system. Since the voltage in the power grid may fluctuate due to changes in the load, the power transformer can maintain the stability of the output voltage by adjusting the turns ratio and the tap position, thus protecting the load equipment from voltage fluctuations.

Overall, the work of power transformer is based on the principle of electromagnetic induction. By changing the turns ratio of the coil and the magnetic flux of the core, it can realise the transformation of voltage, current and impedance, while maintaining the stability of the output voltage to provide reliable power supply for the power system.

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The working principle of the transformer is electromagnetic induction, but strictly speaking, it is because of the mutual induction phenomenon. The following is an explanation of the induction law and the mutual induction phenomenon:

Principle of electromagnetic induction: When the magnetic flux associated with the coil changes (or we can understand that the magnetic flux passing through or through the coil changes), the coil will induce an electromotive force (electromotive force is a physical quantity used to characterize the power supply, commonly known as current), and when the magnetic flux passing through the coil keeps changing continuously, this induced electromotive force (induced current) will be generated continuously accordingly. This is the most intuitive explanation of "electromagnetism".

Specifically, according to Faraday's electromagnetic induction principle, the amplitude of the induced electromotive force (induced current) is proportional to the rate of change of the magnetic flux passing through the coil. We can explain this statement more intuitively in a mathematical way,, where E is the induced electromotive force, N is the number of turns of the coil, and is the rate of change of the magnetic flux.

Let's look at mutual inductance: the changing alternating current in the primary coil generates a changing magnetic field, and the changing magnetic field passes through the secondary coil, which induces an electromotive force in the secondary coil, that is, an induced current: EMF. Mutual inductance is a direct result of Faraday's law.

Transformers are the best example of mutual inductance, and we define it as follows: when a changing current in one coil induces an electromotive force (current) in another adjacent coil, the phenomenon that occurs is called mutual inductance (which is what we commonly call "electricity generates magnetism, magnetism generates electricity").

In detail, according to Lenz's law, the current generated by the mutual inductance between two coils is affected by the mutual inductance coefficient (the mutual inductance coefficient (M) quantifies the degree of mutual inductance between the two coils), which is measured in Henry (H) according to electronic data. The mutual inductance of the two coils is the same. .