Power transformers are electrical equipment used to change the voltage of alternating current. Based on the principle of electromagnetic induction, the transformer exchanges a certain level of AC voltage into another level of AC voltage to meet the needs of different loads.
There are many types of transformers, which can be based on step-up and step-down transformers (step-up transformers and step-down transformers), a number of phases (three types of single-phase transformers, three-phase transformers, and multiple transformers), and uses (power transformers used in power supply systems); Instrument transformers used for measurement and relay protection, etc.), structure, cooling method (there are dry-type transformers cooled by air; oil-immersed transformers cooled by oil; water-cooled transformers cooled by water), etc.
The output voltage of the generator is limited by the insulation level of the generator, usually, 6.3KV, 10.5KV, and the highest do not exceed 20KV. When delivering a certain power of electrical energy, the lower the voltage, the greater the current, and most of the electrical energy may be consumed by the resistance of the transmission line.
Therefore, a step-up transformer can only be used to increase the terminal voltage of the generator to tens of thousands of volts to hundreds of thousands of volts in order to reduce the transmission current and reduce the energy loss on the transmission line without increasing the cross-section of the wire to transmit the electric energy over a long distance.
After the transmission line transmits tens of thousands of volts or hundreds of thousands of volts to the load area, the high voltage must be reduced to a low voltage suitable for use by electrical equipment through a step-down transformer.
For this reason, in the power supply system, a step-down transformer is required to convert the high voltage transmitted by the transmission line into various levels of voltage to meet various complex needs(portable step down transformer). Therefore, the transformer occupies a very important position in the power system and the power supply system.