Guide
1
Turn raw data into the units used in the SI system: voltage - volts, power - in watts.If the load is powered by direct current, simply divide the power voltage, and you know it consumed current expressed in amperes.
2
AC voltage has two values: the current and peak.On power sources usually indicates the first of them.The relationship between these values ​​depends on the shape of the voltage and the number of phases.If the voltage is sinusoidal, and a single-phase network, multiply the current value of the square root of two, and you get the peak.On the contrary, by dividing the peak value by the same amount, you get action.Note that the power is determined by the actual value of voltage and current.If you want to know the latest peak value, first the above process steps, and then
multiply it by the square root of two.Amperage, which must be calculated lead wires and fuses, are also calculated based on the actual value of this quantity.
3
loads for the connection of the three-phase network design so that the currents consumed by them in all three phases, were close.A small difference currents in the phase conductors, caused in particular by the presence of not only the power circuits, and control circuits normally be neglected.When calculating the current absorbed by the three-phase load, the power to divide the stress acting between any two phase conductors and not between any of them and the neutral conductor.To get the first of these stresses, the second multiply by the square root of three.The total current of all three phases is divided into three, and you will find the current in each of the phase conductors.
4
addition to the active loads, there are reactive - inductive and capacitive.In addition to power consumption, they are characterized by another parameter - the power factor.Usually, it is specified on the device.To find reactive power, active, multiply by this factor.Then, by dividing the active power of voltage, current, calculate the active component and dividing the reactive power at the same voltage - reactive component of the current.Adding the two components together, consider the results when the current fuse to blow, and the cross section of the leads.