Calculation of the power of electric current - calculation formula and online calculation

The correct calculation of the power of electric current is a very important aspect that is of great importance for your safety during the operation of electrical wiring. In general, the fire safety of the entire structure depends on the correct implementation of these calculations, as well as the correct choice of cable cross-section. And all because if you choose the wrong cross-section of the cable, a short circuit may subsequently occur and, as a result, the ignition of electrical wires, from which the entire room (building) may catch fire. As for the choice of a suitable section, it depends on many different indicators. However, the most basic of all is the current strength.

How to calculate the power of electric current? (formula)

In the case when the circuit is active, the current strength in it can be measured using a specialized device - an ammeter. But what about if only a building project is being drawn up? After all, it is impossible to measure the current strength in a non-existent circuit. In this case, you should use the calculation method.

The current strength is calculated by the formula, if we know such indicators as: power, mains voltage and the nature of the load:

• If the network is 1-phase, the formula I = P / (U * cos φ) is used;
• If the network is 3-phase, I = P / (1.73 * U * cos φ),

In this case: P is the power of the electrical load, W; U is the actual voltage in the network, V; cos φ - is the coefficient. power.

To determine the power, it is necessary to sum up the power of the devices that are planned to be put into operation and, accordingly, will be connected to our network. Often, these values ​​are available in the passports of electrical appliances, or are taken from the known values ​​​​of similar electrical appliances. This indicator must be calculated when it is only planned to conduct electrical wires in the apartment.

As for the power factor, it directly depends on what kind of load is planned. For example, if we are talking about lighting lamps or heating devices, then it is equal to one. However, in any active load there are reactive components, which is why the coefficient. power consider 0.95. Depending on the types of wiring, this factor must be taken into account!

So, if the devices and equipment are powerful enough (for example, it can be a welding machine, an electric motor, etc.), they already have a higher proportion of reactive load. Accordingly, the coefficient power for such devices will be 0.8.

If the current is single-phase, the voltage of 220 W is accepted in the network, in the case of a 3-phase current - 380 W. Despite this factor, in order for the accuracy to be maximum, if possible, it is still worth using calculations of the actual voltage values ​​that you will measure using special instruments.