【 Weak current College 】 transformer classification, power transformer parameters, audio transformers and high-frequency transformer parameters 】

Transformer

Transformer is transform AC voltage, current, and resistance of the device, when the primary coil in a AC current, core (or cores) will produce AC flux, makes the secondary coil induces voltage in (or current). Transformer from core (or cores) and coil, coil has two or more winding, which received the power of the primary coil winding is called, the rest of the winding is called secondary coils.

I. classification
Classification by: dry cooling methods (from cold), oil-immersed transformer (from cold) transformers, fluoride (evaporative cooling) transformer.
The moisture-proof manner classification: open transformer, encapsulation type transformer, sealed transformer.
By core or coil structure classification: core type transformer (plate iron core, C-core, ferrite cores), shell transformer (plate iron core, C-core, ferrite cores), ring-type transformer, metal foil transformer.
Press the power phase classification: single phase transformer, three-phase transformers, poly-phase transformer.
Classification by purpose: power transformers, voltage transformers, audio transformers, intermediate frequency transformers, high-frequency transformer and pulse transformers. Second, power transformer parameters

1. working frequency
Transformer core loss and frequency relationship is very large, it should be based on frequency of use to design and use, of such frequency that frequency.
2. rated power
The frequency and voltage transformer for long-term work, not exceeding the prescribed temperature rise of output power.
3. rated voltage
Means the transformer coils on the allowable voltage, imposed work cannot be larger than specified value.
4, voltage ratio
Means the voltage transformer primary and secondary voltage ratio, there is no load voltage ratio and load voltage ratio of distinction.
5, the load current
The transformer secondary open circuit, the primary there is still a current, this part of the current known as no-load current. No-load current by magnetizing current (flux) and iron loss current (caused by the core loss). For 50Hz power transformers, no-load current basically equal to the magnetic current.
6, no-load loss
Means the transformer secondary road, at the primary level measured power loss. Major loss is the core loss, followed by the load current in the primary coil copper resistance on consumption (copper), this part of the loss is very small.
7. efficiency
Refers to the secondary power P1 P2 and primary power ratio percentage. Usually transformer rating, the greater the higher efficiency.
8, insulation resistance
Indicates that the coils in transformers, coils and between core insulation performance between. Insulation resistance of the high and low and insulation performance, high or low temperature and moisture levels. 3. audio transformers and high-frequency transformer parameters

1, frequency response
Means the transformer secondary output voltage with the frequency changes.
2, passband
If the intermediate frequency transformer in output voltage U0, when the output voltage (input voltage remains the same) to the range of frequencies when 0.707U0, known as the passband B transformer.
3. primary and secondary impedance ratio
Transformer's primary and secondary access appropriate impedance Ro and Ri, the transformer's primary and secondary impedance matching, Ro and Ri ratio known as the primary and secondary impedance ratio. Impedance matching, transformers work at your best, most efficient transfer.