Active power: Electric energy is used to do work and is consumed. They are converted into thermal energy, light energy, mechanical energy or chemical energy, etc., called active power; also called average power. The instantaneous power of alternating current is not a constant value. The average value of power in a period is called active power, which refers to the power consumed by the resistance part of the circuit, represented by the letter P, in watts.
Reactive power: In an AC circuit with inductance and capacitance, the magnetic field of the inductor or the electric field of the capacitor absorbs energy from the power supply for a part of a period, and returns the energy to the power supply for another part of the period. The average power in the entire cycle is zero, that is, there is no energy consumption. But energy is exchanged back and forth between the power supply and the inductor or capacitor. The maximum value of the energy exchange rate is called reactive power. For example, a 40-watt fluorescent lamp requires more than 40 watts of active power (the ballast also consumes part of the active power) to emit light, and also requires about 80 kW of reactive power for the coil of the ballast to establish an alternating magnetic field. Because it does not do external work, it is called "reactive". The symbol of reactive power is represented by Q, and the unit is var or kilovar (kVar).
The role of reactive power in the power grid: Reactive power is relatively abstract. It is used to exchange electric and magnetic fields in a circuit, and to establish and maintain a magnetic field in electrical equipment. It does not work externally, but transforms into other forms of energy. All electrical equipment with electromagnetic coils consumes reactive power to build a magnetic field. After the inductive electrical equipment in the distribution network, such as transformers, motors, electric welding machines, air conditioners, washing machines, refrigerators, sodium lamps, fluorescent lamps, etc., are put into operation, they must not only absorb active power from the power network for work, but also absorb The power builds up a magnetic field, which results in the natural power factor of the electricity customers generally being relatively low.
The role of active power: the electrical power required to maintain the normal operation of electrical equipment, that is, to convert electrical energy into other forms of energy (mechanical energy, light energy, thermal energy).
In summary, there is no need to pay for reactive power!