Transformer is not the main and vice two coils? Resistance into which ah?
The significance of no - load power factor of power transformer
The power transformer is likely to run without load, while the low power factor will increase the grid supply voltage. When the power transformer is unloaded, the no-load current is mainly used to establish the transformer core excitation and provide the excitation loss. The excitation current is part of the current current is reactive current, the general design, the power transformer power factor is low.
When the power transformer winding side of the application of sinusoidal AC, the magnetic field is also sinusoidal changes in the magnetic field. However, the core of the transformer is a non-linear magnetically permeable material, so the field current that produces the magnetic field must be non-sinusoidal. Generally appear as "steeple". Figure 1 for a single-phase transformer no-load current waveform and its harmonic spectrum.
Transformer no-load operation, the output power is zero, no-load power is equal to no-load loss. In the case of loss of fixed, the smaller the no-load current, the higher the no-load power factor. Therefore, the power transformer no-load power factor is higher, the better the no-load current is better. Increasing the no-load power factor is one of the main technical research directions of power transformer manufacturers, and reducing the no-load current is an important technical means to improve the no-load power factor.
Transformer calculates power factor
If the capacity of the power transformer is denoted by S, the output active power is expressed by P, then the power factor cosa = P / S.
Transformer Efficiency = Output Power / Input Power * 100%
The input power of the transformer will be larger, and the output power is the power difference of the input power minus the loss. Or the input power of the input power transformer plus the sum of the transformer losses. If you know the efficiency of the transformer, then the input power is the transformer output power and transformer efficiency ratio. General small capacity transformer, the efficiency of about 90%, large capacity transformer, the efficiency of 98%. Each motor system consumes two power, namely the real useful work (called kw) and the reactive power. The power factor is the ratio between the useful power and the total power. The higher the power factor, the higher the ratio between the useful power and the total power, and the system is more efficient.
