A transformer is a device that uses the principle of electromagnetic induction to change alternating voltage. Its main components are the primary coil, secondary coil, and iron core (magnetic core). In electrical equipment and wireless circuits, it is commonly used for voltage step-up and step-down, impedance matching, safety isolation, etc.
When a transformer leaves the factory, it is determined whether it will be used as a step-up transformer or a step-down transformer, and its relay protection settings are specified accordingly. If the transformer is a step-up transformer, it is determined to start voltage boosting from the low-voltage side at zero voltage. If reverse charging is applied from the high-voltage side, the low-voltage side is open-circuited. Due to the capacitive current on the high-voltage side, overvoltage may be induced on the low-voltage side by electrostatic induction, which can easily damage the low-voltage winding. If the transformer is normally charged from the high-voltage side, and reverse charging is applied from the low-voltage side, the high-voltage side is open-circuited. However, due to the large inrush current (which can reach 6 to 8 times the rated current), the resulting electromagnetic force can seriously threaten the mechanical strength of the transformer.
