Apparent power

In an AC circuit, the product of the rms value of the voltage and the rms value of the current is regarded as the apparent power, which has the units of volt-amperes and kilovolt-amperes. For single-phase power, the apparent power is equal to the phase voltage multiplied by the phase current, and for three-phase power, the apparent power is equal to the root 3 times the phase voltage multiplied by the phase current. At the beginning it is mentioned that apparent power in an AC circuit it can be expressed as the maximum power provided, but this maximum power has two parts, active power and reactive power, that is, the two types of electrical power provided by the power supply to the load. For the load there are three types of loads, inductive loads, capacitive loads, resistive loads, of which only resistive loads, the power supply to provide how much electric power to use how much, there is no reactive power consumption. Therefore, if a resistive load is used in an AC circuit, the apparent power is equal to the active power.

Reactive power

In an electric circuit, reactive power is used for the exchange of electric and magnetic fields within the circuit, for example, in inductive loads is the electric power used to establish and maintain the magnetic field. It does not do work externally, but is transformed into other forms of energy. For example, the motor used in the industrial production process, its electromagnetic coil to establish a magnetic field, then the consumption of reactive power.

The above mentioned active power, reactive power, apparent power, and power factor. For example, there are resistive and inductive loads of this type, in the AC circuit that is to consume active power and reactive power consumption, but hope that the consumption of active power more than the consumption of reactive power more, so to react to the degree of active power consumption is the power factor. The higher the power factor indicates that the equipment can consume more active power, so the power factor can also react to the rational use of power equipment, can also react to the degree of power utilization, can also react to the level of power management, so the power is a very important technical indicators.

Therefore, the apparent power indicates the capacity of the electrical equipment, which may also be the maximum active power consumed by the circuit, or the maximum power provided by the circuit. The active power is the energy that can convert the electrical energy in the circuit into other forms of energy, such as light energy, thermal energy, mechanical energy and other energy. Electrical equipment generally uses kVA as a unit, such as contactless voltage regulators, inverter power supplies, etc., but DC power supplies use KW as a unit.