What Is the Relationship Between Power VA and W?

Generally, it is explained that VA, W, and Var are not power, they are just units of power, which are units of apparent power (represented by S), active power (represented by P), and reactive power (represented by Q).

Remember that it is active and reactive, it is not useful and useless.

What is the relationship between them, let's look at their formula?

Apparent power: S=UI

Active power: P=UIcosΦ

Reactive power: Q=UIsinΦ

The cosine of the phase difference (Φ) between the voltage and current is called the power factor and is represented by the symbol cosΦ.

According to the formula, the relationship between them is: S2=P2+Q2

In an AC circuit, there are two types of power supplied by the power supply to the load: one is an active power, and the other is reactive power.

Active power is the electrical power required to maintain the normal operation of electrical equipment, that is, electrical power that converts electrical energy into other forms of energy (such as mechanical energy, light energy, and thermal energy).

Reactive power is relatively abstract. It is used for the exchange of electric and magnetic fields in circuits and is used to establish and maintain magnetic fields in electrical equipment. It does not do external work but transforms into other forms of energy. All electrical equipment with electromagnetic coils will consume reactive power to establish a magnetic field. Reactive power is by no means useless power, it is very useful. The motor needs to establish and maintain a rotating magnetic field to make the rotor rotate, thereby driving the mechanical movement. The rotor magnetic field of the motor is established by obtaining reactive power from the power supply. The transformer also needs reactive power to generate a magnetic field in the primary coil of the transformer and induce a voltage in the secondary coil. Therefore, without reactive power, the motor cannot turn, and the transformer cannot change the voltage.

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