Transformer classification and characteristic analysis

Transformer is a device that uses the principle of electromagnetic induction to change the AC voltage. The main components are the primary coil, the secondary coil and the iron core (magnetic core). The main functions are: voltage conversion, current conversion, impedance transformation, isolation, voltage regulation (magnetic saturation transformer) and so on. According to the use, it can be divided into: distribution transformer, power transformer, fully sealed transformer, combined transformer, dry transformer, oil immersed transformer, single phase transformer, electric furnace transformer, rectifier transformer and so on. First, the production principle of the transformer: In the generator, whether the coil moves through the fixed coil through the magnetic field or the magnetic field, the potential can be induced in the coil. In both cases, the value of the magnetic flux is constant, but the number of magnetic fluxes intersecting the coil is Change, this is the principle of mutual induction. A transformer is a device that uses electromagnetic mutual induction to transform voltage, current, and impedance. Second, classification Classified by cooling method: dry (self-cooling) transformer, oil immersed (self-cooling) transformer, fluoride (evaporative cooling) transformer. Classified according to the moisture-proof method: open transformer, potted transformer, sealed transformer. According to the iron core or coil structure classification: core transformer (insert core, C core, ferrite core), shell transformer (insert core, C core, ferrite core), Ring transformer, metal foil transformer. Classified by power phase number: single-phase transformer, three-phase transformer, multi-phase transformer. Classified by use: power transformer, voltage regulating transformer, audio transformer, intermediate frequency transformer, high frequency transformer, pulse transformer. Third, the power transformer's characteristic parameters The working frequency transformer core loss has a great relationship with frequency, so it should be designed and used according to the frequency of use. This frequency is called the working frequency. Rated power At a specified frequency and voltage, the transformer can operate for long periods of time without exceeding the output power of the specified temperature rise. The rated voltage refers to the voltage that is allowed to be applied to the coil of the transformer and must not be greater than the specified value during operation. The voltage ratio refers to the ratio of the primary voltage to the secondary voltage of the transformer, and has the difference between the no-load voltage ratio and the load voltage ratio. When the no-load current transformer is open secondary, there is still a certain current in the primary. This part of the current is called no-load current. The no-load current consists of magnetizing current (generating magnetic flux) and iron loss current (caused by core loss). For a 50 Hz power transformer, the no-load current is substantially equal to the magnetizing current. No-load loss refers to the measured power loss at the primary when the transformer is open secondary. The main loss is the core loss, followed by the loss (copper loss) of the no-load current on the primary coil copper resistance, which is small. Efficiency refers to the percentage of the ratio of the secondary power P2 to the primary power P1. Generally, the higher the rated power of the transformer, the higher the efficiency. The insulation resistance represents the insulation performance between the coils of the transformer and between the coils and the iron core. The insulation resistance is related to the performance of the insulating material used, the temperature and the degree of humidity.