In an AC circuit, the cosine of the phase difference between the voltage and the current is called the power factor, which is represented by the symbol cos diameter. In the numerical value, the power factor is the ratio of the active power to the apparent power, that is, the cos =P/S.

The power factor is related to the load character of the circuit. For example, the power factor of the resistance load, such as incandescent bulb and resistance furnace, is 1, and the power factor of the circuit with inductance or capacitance load is less than 1. Power factor is an important technical data of power system. Power factor is a measure of the efficiency of electrical equipment. The power factor is low, which indicates that the reactive power of the circuit used in the alternating magnetic field conversion is large, thereby reducing the utilization ratio of the equipment and increasing the loss of the power supply of the line. Therefore, the power supply department has certain standard requirements for the power factor of the power unit.

(1) the most basic analysis: take the equipment as an example. For example, the power of the device is 100 units, that is to say, 100 units of power are transported to the equipment. However, due to the inherent reactive power loss of most electrical systems, only 70 units of power can be used. Unfortunately, even though only 70 units are used, it costs 100 units. In this example, the power factor is 0.7 (if the power factor of most devices is less than 0.9, it will be fined). This kind of reactive loss is mainly in the motor equipment (such as blower, pump, compressor, etc.), also called inductive load. The power factor is the measurement standard of the motor efficiency.

(2) basic analysis: each motor system consumes two power, which are real work (kw) and reactance useless work. Power factor is the ratio of active power to total power. The higher the power factor, the higher the ratio between useful work and total power, and the more efficient the system works.

(3) advanced analysis: in inductive load circuit, the peak value of current waveform occurs after the peak value of voltage waveform. The separation of the peaks of the two waveforms can be expressed by the power factor. The lower the power factor, the larger the two peak value is. Paulkin can bring the two peaks closer together so as to improve the efficiency of the system.