Transformers are made based on electromagnetic induction. It consists of a core made of stacked silicon steel sheets (or silicon steel sheets) and two sets of coils wound around the core. The core and coils are insulated from each other and have no electrical connection, as shown in the figure. We call the coil connected between the transformer and the power supply side the primary coil (or primary side), and the coil connected between the transformer and the electrical equipment the secondary coil (or secondary side). When the primary coil of a transformer is connected to an AC power source, magnetic field lines will change in the iron core. Due to the secondary coils being wound around the same iron core, magnetic field lines cut through the secondary coils, which inevitably generates induced electromotive force on the secondary coils, resulting in voltage at both ends of the coils. Because magnetic field lines are alternating, the voltage of the secondary coil is also alternating. And the frequency is exactly the same as the power frequency.
The manager argued that the voltage ratio between the primary and secondary coils of a transformer and the ratio of the number of turns between the primary and secondary coils are related, which can be expressed as follows: primary coil voltage/secondary coil voltage=primary coil turns/secondary coil turns, indicating that the more turns there are, the higher the voltage. Therefore, it can be seen that there are fewer secondary coils than primary coils, which is a step-down transformer. On the contrary, it is a step-up transformer.
The coil has dual windings and multiple windings, and is an autotransformer. It can be divided into oil immersed and air-cooled according to the cooling method.
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