The transformer works on the principle of electromagnetic induction. A transformer has two sets of coils. primary coil and secondary coil. The secondary coil is outside the primary coil. When the primary coil is supplied with alternating current, the transformer core generates an alternating magnetic field, and the secondary coil generates an induced electromotive force. The turns ratio of the coils of the transformer is equal to the voltage ratio. For example: the primary coil is 500 turns, the secondary coil is 250 turns, the primary is connected to 220V AC, and the secondary voltage is 110V. A transformer can step down as well as step up. If the primary coil has fewer turns than the secondary coil, it is a step-up transformer, which can increase the low voltage to a high voltage.
Transformer components include body (iron core, winding, insulation, lead wire), transformer oil, oil tank and cooling device, pressure regulating device, protection device (moisture absorber, safety gas Road, gas relay, oil conservator and temperature measuring device, etc.) and outlet bushing. The specific composition and functions are as follows.
(1) Iron core. The iron core is the main magnetic circuit part of the transformer. It is usually made of stacked hot-rolled or cold-rolled silicon steel sheets with high silicon content, thicknesses of 0.35mm, 0.3mm, and 0.27mm, and insulating paint on the surface. The iron core is divided into two parts: the iron core column and the horizontal piece. The iron core column is covered with windings; the horizontal piece is used to close the magnetic circuit.
(2) Winding. The winding is the circuit part of the transformer, which is wound with double-wire insulated flat wire or enamelled round wire. The basic principle of the transformer is the principle of electromagnetic induction. Now take the single-phase double-winding transformer as an example to illustrate its basic working principle: when the voltage U1 is applied to the primary side winding, the current I1 flows, and an alternating magnetic flux is generated in the iron core. O1, these fluxes are called the main flux, under its action, the windings on both sides induce potentials respectively, and finally drive the transformer control device.
The function of AC transformer: voltage transformation, current transformation, impedance transformation, isolation, voltage stabilization (magnetic saturation transformer)
1) Power transformer: used for raising and lowering the voltage of the power transmission and distribution system.
2) Instrument transformers: such as voltage transformers, current transformers, used for measuring instruments and relay protection devices.
3) Test transformer: It can generate high voltage and conduct high voltage test on electrical equipment.
4) Special transformers: such as electric furnace transformers, rectifier transformers, adjustment transformers, capacitive transformers, phase-shifting transformers, etc.
