Power transformer is a kind of stationary electrical equipment, which is used to change the AC voltage (current) of a certain value into another or several different values of voltage (current). When the primary winding is connected with alternating current, the alternating magnetic flux is produced, and the alternating magnetic flux induces the AC electromotive force in the two winding through the magnetic conduction of the iron core.
Power transformer is one of the main equipments in power plant and substation. The function of transformer is various, it can not only increase the voltage, send the electric energy to the power supply area, but also reduce the voltage to the use voltage at all levels, in order to meet the needs of electricity. In short, step-up and step-down must be done by transformers. In the process of transmission of electric energy in power system, two parts of voltage and power will inevitably be produced. When the same power is transported, the voltage loss is inversely proportional to the voltage, and the power loss is inversely proportional to the square of the voltage. The transformer is used to increase the voltage and reduce the loss of power supply.
The transformer is composed of two or more coil windings around the same core. The windings are connected by alternating magnetic field and work according to the electromagnetic induction principle. The winding is composed of two windings. Transformer installation location should be considered for easy operation, maintenance and transportation, and safe and reliable places should be selected. The rated capacity of transformer must be selected reasonably when using transformer. When the transformer is running without load, it needs larger reactive power. These reactive power should be supplied by the power supply system. If the transformer capacity is too large, not only increase the initial investment, but also the transformer no-load or light load operation in the long term, to increase the proportion of no-load loss, lower power factor, network loss increase, so the operation is not economical and reasonable. Transformer capacity selection is too small, will make the transformer long-term overload, easy damage to equipment. Therefore, the rated capacity of transformer should be chosen according to the needs of power load, not too