How does a transformer change voltage?



The transformer is made of electromagnetic induction. It consists of an iron core laminated with silicon steel sheets (or silicon steel sheets) and two groups of coils wound on the iron core. The iron core and coils are insulated from each other without any electrical connection, as shown in the figure. The coil connecting the transformer and the power supply side is called the primary coil (or the primary side), and the coil connecting the transformer and the electrical equipment is called the secondary coil (or the secondary side). When the primary coil of the transformer is connected to the AC power supply, there will be variable magnetic lines of force in the iron core. As the secondary coil is wound on the same iron core, the magnetic line of force cuts the secondary coil, and the induced electromotive force will inevitably be generated on the secondary coil, causing voltage at both ends of the coil. Because the magnetic line of force is alternating, the voltage of the secondary coil is also alternating. And the frequency is exactly the same as the power frequency.

The manager demonstrated that the voltage ratio of the transformer primary coil to the secondary coil and the ratio of the turns of the primary coil to the secondary coil are related, which can be expressed by the following formula: the voltage of the primary coil/the voltage of the secondary coil=the turns of the primary coil/the turns of the secondary coil. The more turns, the higher the voltage. Therefore, it can be seen that the secondary coil is less than the primary coil and is a step-down transformer. On the contrary, it is a step-up transformer.