Electrician: Basic knowledge of 16 transformers. Teacher Fu said that 12 is already very impressive!（Ⅰ）

1. What is a transformer?

In an AC circuit, the device that raises or lowers the voltage is called a transformer. The transformer can convert any value of voltage into the voltage value we need with the same frequency to meet the requirements of energy transmission, distribution, and use. For example, the electricity generated by a power plant has a low voltage level, and the voltage must be raised in order to be transmitted to a distant electricity consumption area. The electricity consumption area must be reduced to a suitable voltage level through voltage reduction to supply power equipment and daily electrical equipment.

2. How does a transformer change voltage?

Transformers are made based on electromagnetic induction. It consists of an iron core stacked with silicon steel sheets (or silicon steel sheets) and two sets of coils wound around the iron core. The iron core and coils are insulated from each other and have no electrical connection, as shown in the figure. We refer to the coil connecting the transformer to the power supply side as the primary coil (or primary side), and the coil connecting the transformer to the electrical equipment as the secondary coil (or secondary side). When the primary coil of a transformer is connected to an AC power source, a changing magnetic field line will be generated in the iron core. Due to the fact that the secondary coil is wound around the same iron core, the magnetic line of force cuts the secondary coil, which inevitably generates an induced electromotive force on the secondary coil, causing voltage to appear at both ends of the coil. Because the 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 has proven that the voltage ratio between the primary and secondary coils of a transformer is related to the ratio of turns between the primary and secondary coils, which can be expressed as follows: primary coil voltage/secondary coil voltage=number of turns in the primary coil/number of turns in the secondary coil, indicating that the more turns there are, the higher the voltage. Therefore, it can be seen that the secondary coil is less than the primary coil, which is a step-down transformer. On the contrary, it is a step-up transformer.

3. What are the types of transformer designs?

There are single-phase and three-phase transformers according to the number of phases. It is divided into power transformer, special power transformer, voltage regulating transformer, measuring transformer (Voltage transformer, current transformer), small power transformer (used for small power equipment) and safety transformer according to the purpose. It is divided into core type and shell type according to the structure. The coil has double winding and multi winding, and Autotransformer can be divided into oil immersed type and air cooled type according to the cooling mode.

4. What are the components of a transformer?

The transformer components are mainly composed of iron cores and coils, as well as oil tanks, conservators, insulation sleeves, and tapping heads. 5. What is the use of transformer oil?

The function of transformer oil is: (1) insulation effect. (2) Heat dissipation effect. (3) Eliminate the arc effect.