Different types of transformers have corresponding technical requirements, available appropriate technical parameters indicate. The main technical parameters such as power transformers are: rated power, rated voltage and voltage ratio, rated frequency, temperature levels, temperature, voltage regulation, insulation and moisture resistance. For the average frequency transformer main technical parameters are: transformer ratio, frequency, nonlinear distortion, magnetic shielding and electrostatic shielding efficiency.

Transformer principle
Voltage ratio:
Transformers line circle the number two respectively N1 and N2, N1 is the primary, N2 as the secondary. On the primary coil is an AC voltage in the secondary coil will be induced electromotive force at both ends. When N2> N1, its primary EMF than the applied voltage is even higher, such a transformer called step-up transformer; when N2 <N1, its primary EMF than the applied voltage is low, such a transformer called step-down transformer.
n = N1 / N2
Where n is called the voltage ratio (turns ratio). When n> 1, the N1> N2, U1> U2, the transformer step-down transformer. On the other hand, compared with step-up transformer.