How is the calculation of electrical load

Before proceeding with the design of electriciansin your house, apartment, in the country, you must first make a calculation scheme, which will indicate all the expected loads in the premises, as well as the length of individual sections of the cable. To compile such a map, you will also need to calculate the electrical load. Correctly designed scheme of the electrical system of the object will allow to select wires and cables of required sections. In cases where the cable cross-section is smaller than required for normal functionality of high-power power units, the cable begins to overheat. And as a result, the insulation is destroyed. As a result, the duration of operation and the level of reliability of the wiring is significantly reduced. Moreover, overheating of the cable can lead to ignition. Similar situations happen very often, when the tenants (for the sake of economy) use the wire cross-section, less than necessary. As a result, short circuits and fires occur. Let's figure out what the calculation of the electrical load is.

The correctness of the choice of switching devices, andalso the cross-section of the cable largely depends on the different values ​​of the parameters of electrical networks. The most important of these is the electric current of the load. At the design stage, this value can be determined exclusively by a mathematical method. It is very important to calculate the electrical load in three-phase networks, since the load in them must be placed evenly among the phases in order to avoid distortions of voltage. However, in household networks, such a calculation should be carried out when designing not only board, but also residential premises.

Calculation of electric load is carried out atknown values ​​of the power of electrical devices, the nature of the loads, as well as the voltage of the network. For single-phase networks use the formula for determining the load current: I = P / (U × cosφ), where:

• U - the value of the actual voltage of the network (measured in volts);
• cosφ is the corresponding power factor.

For three-phase networks, the calculation of electrical loads is carried out according to the following formula: I = P / (1.73 × U × cosφ).

Depending on the nature of the load,power factor value. When calculating a high-power reactive load (chokes of lighting devices, electric motors, welding transformers, etc.), an average value of cosφ = 0.8 is adopted. When determining the power current for the active loads (heating elements, incandescent lamps), the power factor is approximately equal to one. However, in any active load, a reactive component is always present, so it is customary to use cosφ = 0.95 for calculations.

In conclusion, we recall that electricity is notforgives mistakes, it will not give a second chance. Safety, as well as the reliability of electrical systems - that's what any professional electrician strives for. And it does not matter where he works: in industry or in the private sector. Electric load is one of the most important design parameters that must be taken into account in any system.