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# Transformer efficiency and voltage ratio

Transformer efficiency, voltage ratio are both nouns, but also has a deep meaning.
A. Transformer efficiency:
At rated power, the transformer output power and input power ratio, called the efficiency of the transformer, that is
Η = x100%
Where η is the efficiency of the transformer; P1 is the input power, P2 is the output power.
When the transformer output power P2 is equal to the input power P1, the efficiency η is equal to 100%, the transformer will not produce any loss, but in fact this transformer is not Transformer transmission of energy always have to produce loss, the loss of copper Loss and iron loss.
Iron loss of the transformer includes two aspects:
1, hysteresis loss, when the AC current through the transformer, through the magnetic field lines of the transformer silicon steel its direction and size change, making the silicon steel friction within the molecules, release heat, which is part of the loss of power, which is hysteresis loss .
2, eddy current loss, when the transformer work. Iron core has a magnetic field line through, in the magnetic field lines perpendicular to the plane will have induced current, since the current form a closed loop loop, and into a spiral, it is called eddy current The existence of eddy current causes the core to generate heat and consume energy, which is called eddy current loss.
Copper loss refers to the loss caused by the resistance of the transformer winding.When the current through the coil resistance heating, part of the energy into heat loss.As the coil is generally wound with insulated copper wire, so called copper loss.
B. Voltage ratio:
The number of turns of the two coils of the transformer is respectively N1 and N2, N1 is the primary, and N2 is the secondary. When an AC voltage is applied to the primary coil, an induced electromotive force is generated at both ends of the secondary coil. When N2> N1, Electromotive force is higher than the primary voltage added, this transformer is called the step-up transformer: When N2
Where n is called the voltage ratio (turns ratio) .When n <1, then N1> N2, V1> V2, the transformer is a step-down transformer, and vice versa is the step-up transformer.
The efficiency of the transformer is closely related to the power level of the transformer. Generally, the larger the power, the smaller the loss and the output power, the higher the efficiency. the smaller the power, the lower the efficiency. 