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# Calculator of reactive power from voltage and current

The reactive power calculator in AC circuits will help you easily calculate reactive power, voltage and current.

## Calculator of reactive power from voltage and current - information

Reactive Power in AC circuits is a quantity that describes the pulsation of electricity between parts of an electrical circuit. This oscillating energy is not converted into useful work or heat, but is nevertheless necessary for the functioning of electrical machines (e.g. transformers, motors). Energy is taken from the source in part of the alternating waveform period, stored by the receiver (in the form of electric or magnetic field energy) and returned to the source in another part of the period, which is related to the disappearance of the field in the receiver.

For sinusoidal variables, reactive power is defined as the product of RMS voltage and current, and the sine of the phase shift angle between voltage and current: $$Q={UI}\sin \varphi$$ where: $$U$$– RMS voltage
$$I$$– RMS current value
$$\varphi$$ - phase angle

We distinguish:
inductive reactive power;
capacitive reactive power.

The unit of reactive power (Q) is var (Volt Ampere Reactive).
In the power industry, the Mvar unit is most often operated.

The presence of reactive power causes an increase in the current intensity, which increases the losses of electricity in devices generating and transmitting AC electricity (generators, transmission lines and transformers).

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