Few people know the difference between a three-phase and single-phase system, as well as the difference between a voltage of 220 V or 380 V. It is very simple to understand these two systems, and it is not necessary to be an electrician or power engineer, such knowledge will simply become a small part of erudition.
What is three-phase voltage
Why exactly 3 phases come to houses, villages and cities, and not 6, 9 or, for example, 12? This is because the number of phases through which current flows under load depends on the design of the generator that generates it. A three-phase network means that machines that generate electricity have exactly 3 poles.
The 3 poles allow the motor rotor to spin when a magnetic field occurs in the stator. It is possible to design motors and generators with a large number of poles, but as practice has shown, this will not lead to any improvements, but only increase the cost of producing such machines.
What do 3 poles give in an electric car
It is best to consider the parameters of a three-phase current using the example of a sinusoid, where it can be seen that each phase (A, B and C) is shifted relative to the other by 120 degrees. But what does such a shift give? Everything is very simple.
The phases are not constant. For example, in a certain period of time, phase A will have a maximum, but with the movement of the generator rotor, it will gradually begin to fade away, approaching the “0” mark. At this moment, on phase "B", the electric current will be in the opposite direction, and phase "C" will take "0".
And with each period the phases change, gradually passing the highs, zero marks and "0". It turns out that any phase complements the next, and the consumer receives continuous and stable voltage.
What is line and phase voltage
When measuring the voltage in a three-phase network, you should accurately understand the concepts of linear and phase potential difference.
Line voltage is measured between two phases: "A" and "B", "B" and "C" or "A" and "C". If there are no distortions in the network, then when the probes touch the current-carrying parts of the two phases, the multimeter should display a value of 380 V. This is the two-phase voltage.
The phase voltage determines the potential difference not between the working phases, but between one phase and the working neutral wire. Then the value will change to 220 V - the household voltage brought into houses and apartments.
Pros of three-phase voltage
The 380 V voltage is universal and is used almost everywhere. Its main advantages:
- Allows you to run powerful electric motors, which are often used in serious industry.
- Three-phase lines are easy to construct and maintain. Several electricians are able to control electrical lines in large industrial plants.
- From 380 V, you can quickly get 220 V by adding only the neutral conductor, which is a separate ground loop.
We should not forget that 380 V and 220 V are dangerous to human life, therefore, when working with both three-phase and single-phase networks, you should first of all protect yourself as much as possible.