Power transformer parameters
B. Transformer efficiency:
In the rated power, the transformer output power and input power ratio, called the efficiency of the transformer, that η = (P2 ÷ P1) 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 the transformer transmission power always produce loss, this loss is mainly copper Loss and iron loss.
Copper loss is the loss caused by the transformer coil resistance.When the current through the coil resistance heat, part of the energy into heat and loss.As the coil is generally wrapped with insulated copper wire, so called copper loss.
The iron loss of the transformer includes two aspects: First, the hysteresis loss, when the AC current through the transformer, through the transformer silicon steel wire magnetic field its direction and size changes, making the silicon steel sheet internal friction, release heat, Part of the energy, which is the hysteresis loss. The other is the eddy current loss, when the transformer work, the magnetic core lines through the line, and the magnetic lines perpendicular to the plane will produce induced current, because the current self-closed loop Circulation, and into a spiral, so called vortex. The presence of eddy current heat, energy consumption, this loss is called eddy current loss.
Transformer efficiency and transformer power levels are closely related, usually the greater the power, loss and output power is smaller, the higher the efficiency, otherwise, the smaller the power, the lower the efficiency.
First, the transformer technical parameters
The main technical parameters of the power transformer are: rated power, rated voltage and voltage ratio, rated frequency, operating temperature class, temperature rise, voltage adjustment Rate, insulation performance and moisture resistance, the main technical parameters for the general low-frequency transformer parameters are: transformer ratio, frequency characteristics, nonlinear distortion, magnetic shielding and electrostatic shielding, efficiency and so on.
A. Voltage ratio:
Transformer two sets of coil turns are N1 and N2, N1 for the primary, N2 for the secondary. In the primary coil plus an AC voltage, the secondary coil will produce both ends of the induced electromotive force. When N2> N1, its induction The electromotive force is higher than the primary voltage. This transformer is called a step-up transformer: when N2 <N1, its induced electromotive force is lower than the primary voltage, which is called a descending transformer. Primary secondary voltage and coil The number of the following relationship: where n is called the voltage ratio (turns ratio). When n <1, then N1> N2, V1> V2, the transformer is a step-down transformer.
