Power formulas, what are they?

Electric power is one of the several magnitudes of electricity, and it is undoubtedly one of the best known to people, but do you really know everything about electric power? The World of Electrical explains what is electrical power, what are the types of electrical power and what are their respective formulas. Come on, guys!

Electric power, what is it?

We can define electrical power as the speed with which a job is performed, that is, it is the speed that something uses to transform electrical energy into another type of energy.
The unit of power in the international measurement system is the watt (W), which pays tribute to the mathematician and engineer James Watts who improved the steam engine.

Types of electrical power

In alternating current circuits, electrical current and electrical voltage behave differently than direct current circuits. We can cite electrical power as differences between DC and AC circuits because in alternate systems there are three types of electrical power, which are:

Types of electrical power – Active power:

Active power is the power that performs useful work on a given load, where its unit of measurement is the watt (W).
Many people know only the active power because normally the basic electrical courses and in schools are taught to calculate power in purely resistive loads such as resistors.

In addition, it is common for many people to know the active power because the electric utilities base the consumer’s electric energy expenditure through KW / h, that is, active power.

Types of electrical power – Reactive power:

We can say that reactive power represents the part of the power that is applied to the capacitive and inductive loads, this power does not perform effective work. Its unit of measure is reactive volt-ampere (VAr). This power is a small part of the total power consumed by induction motors, which for example is necessary to generate an electromagnetic field. If the consumption of reactive power is above the values ​​allowed by the electric utility, a penalty is charged to the consumer.

Types of electrical power – Apparent power:

Apparent power is defined as the total power that a given source is capable of providing, that is, the active power is actually the “vectorial sum” of the active power and the reactive power. The unit of measurement of apparent power is the volt amp (VA).

Power factor, what is it?

When talking about these three types of electrical power, we must take into account a factor that relates them, defined as a power factor (φ), also known as angle fi.
The power factor is a relationship between apparent power and active power, that is, it is the relationship between the amount of energy delivered by the source and the amount of energy that is effectively transformed into work. The higher the power factor of a load, the closer it gets to a resistive load, consuming a greater amount of active power.

Formulas for calculating electrical power

To perform the calculations of electrical power in alternating current circuits, it is essential to have knowledge about the power triangle, because through it it is possible to calculate any of the three powers, for that it is necessary to have a certain degree of knowledge in trigonometry for example. The power triangle is properly represented in the image below:

Power triangle to calculate active, reactive and apparent power.

Formulas for calculating electrical power – Active power:

The formula for calculating active power is relatively simple and is usually that we have a lower degree of difficulty, because when we have the values ​​of the other quantities just apply the ohm law. In the image below we have three different formulas of active power, which were obtained through the ohm law.

Formulas used to calculate active power.

Formulas for calculating electrical power – reactive power:

As with the other types of electrical power, it is possible to obtain the reactive power value having the values ​​of some quantities and the fi angle, as we can see in the image below some formulas to calculate the reactive power.v