Explanation of common parameters of transformers

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Explanation of common parameters of transformers [Copy link]

A transformer is a device that uses the principle of electromagnetic induction to change AC voltage. Its main components are the primary coil, the secondary coil, and the iron core (magnetic core). Its main functions include voltage conversion, current conversion, impedance conversion, isolation, voltage regulation (magnetic saturation transformer), etc. Circuit symbols often use T as the beginning of the number. For example: T01, T201, etc. 1. Transformation ratio: n The transformation ratio of a transformer indicates the relationship between the number of turns of the primary winding and the number of turns of the secondary winding of the transformer. The transformation ratio parameter indicates whether it is a step-down transformer, a step-up transformer, or a 1:1 transformer. The transformation ratio N is calculated by the following formula: n=primary turns/secondary turns=primary voltage/secondary voltage Note: Transformation ratio n<1 is a step-up transformer, the number of primary winding turns is less than the number of secondary winding turns. This type of transformer is used in some igniters. Transformation ratio n>1 is a step-down transformer, the number of primary winding turns is more than the number of secondary winding turns. Ordinary power transformers are this type of transformer. Transformation ratio n=1 is a 1:1 transformer, and the number of turns of the primary winding is equal to the number of turns of the secondary winding. Isolation transformer is this kind of transformer. 2. Frequency response Frequency response is an important parameter to measure the ability of transformers to transmit signals of different frequencies. Note: In the low and high frequency bands, due to various reasons (inductance of the primary winding, leakage inductance), the transformer transmission signal energy loss will be caused, and the frequency effect will be deteriorated. 3. Rated power Rated power refers to the maximum output power of the transformer under the specified frequency and voltage, when it works for a long time without exceeding the specified temperature rise. The unit is volt-ampere. For some transformers, rated power is an important parameter. For example, power transformers have power output requirements, while for other transformers (medium frequency transformers), this parameter is not important. 4. Insulation resistance The insulation resistance is not only related to the performance and quality of the transformer, but also to personal safety in the power transformer, so it is a safety performance parameter. The ideal transformer is between the primary and secondary windings, and each winding should be completely insulated from the core, but this is very difficult to achieve. The insulation resistance is obtained from the test results, as shown below:

(The insulation resistance is measured with a 1KV insulation resistance meter and should be above 10MΩ.) 5. Effect 6. Temperature rise Temperature rise refers to the value that the temperature of the transformer rises to a stable value after power is supplied, which is higher than the ambient temperature. The smaller this value is, the safer the transformer is. 7.Transformer marking method Transformers usually use the direct marking method. The specific content of transformer marking for various purposes is different, and there is no unified format. 8. Transformer parameter description: 1) When replacing, the winding structures of different types of transformers are different. It is necessary to replace the transformers of the same type. We need to optimize the transformer parameters according to different purposes. 2) The main card rate of the power transformer is the secondary winding structure and the size of the AC output voltage. When using different rectifier circuits, there are different requirements for the structure of the transformer secondary winding and the output voltage. In addition to the voltage, the rated power and insulation resistance parameters are also essential reference factors. If the rated power is too small, the transformer will heat up during use and affect safety. Insufficient insulation resistance will also cause leakage of the power transformer and cause unexpected disasters. 3) Frequency response parameters. If this parameter does not meet the requirements, the frequency response index of the entire amplifier system will not meet the requirements.