Transformer basic principle, classification and main parameters
A transformer is a device that converts alternating voltage, current, and impedance. When an alternating current is passed through the primary coil, an alternating magnetic flux is generated in the iron core (or core) to induce a voltage (or current) in the secondary coil. The transformer consists of a core (or core) and a coil. The coil has two or more windings. The winding connected to the power supply is called the primary coil, and the other winding is called the secondary coil. I. 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 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 regulator, audio transformer, intermediate frequency transformer, high frequency transformer, pulse transformer. Second, the characteristics of the power transformer 1 working frequency Transformer core loss has a large relationship with frequency, so it should be designed and used according to the frequency of use. This frequency is called the working frequency. 2 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. 3 rated voltage Refers to the voltage allowed on the coil of the transformer, and should not be greater than the specified value during operation. Refers to the ratio of the primary voltage to the secondary voltage of the transformer, which has the difference between the no-load voltage ratio and the load-to-voltage ratio. 5 no-load current When the secondary of the transformer is open, 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. 6 No-load loss: refers to the power loss measured at the primary when the transformer is open. 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. 7 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. 8 insulation resistance It indicates the insulation performance between the coils of the transformer and between the coils and the iron core. The level of insulation resistance is related to the properties of the insulation used, the temperature and the degree of humidity. Third, audio transformer and high frequency transformer characteristic parameters 1 frequency response Refers to the characteristics of the secondary output voltage of the transformer as a function of operating frequency. 2-pass band If the output voltage of the transformer at the intermediate frequency is U0, the frequency range when the output voltage (the input voltage remains unchanged) drops to 0.707U0 is called the passband B of the transformer. 3 primary and secondary impedance ratio The initial and secondary impedances of the transformer are connected to the appropriate impedances Ro and Ri to match the primary and secondary impedances of the transformer. The ratio of Ro to Ri is called the primary and secondary impedance ratio. In the case of impedance matching, the transformer operates at its optimum state and has the highest transmission efficiency. National standard control cable,Intelligent control line,Cable,Multi functional cable Jiangsu D-Bees Smart Home Co., Ltd. , https://www.cI-hometheater.com