Phase is often heard in conversations about electricity. But, of course, the word has a much broader meaning. What is a phase, its cycles, how is it related to grounding. We will learn about this and much more in the next article.
What is a phase
In physics, a phase is understood as one of the states of matter (for example, water is in a liquid, liquid-crystal, crystalline and gaseous state of aggregation). In addition, it refers to a stage in a cycle of oscillation (for example, in a wave motion).
In astronomy, the word has a slightly different meaning. What is a phase in this science can be understood from observations from the Earth of a celestial body (for example, the Moon). That is, it can be designated as the visible part of the illuminated hemisphere of a celestial object from Earth.
In the theory of economics, it is widely known what the phases of a cycle are. This is when regular activity is observed in a certain period of time (cycle).
Let's consider what this term means in electricity.
Phase in electricity
Do you know where the electricity comes from in power plants? Everywhere principleits occurrence is the same: the rotation of the magnet inside the coil leads to the fact that an alternating current appears in it. This effect is called EMF, or electromotive force of induction. The rotating magnet is called the rotor, and the coils attached around it are called the stator.
Alternating voltage is obtained from a constant when the latter is bent along a sine, resulting in either a positive or a negative value.
So, the magnet moves, for example, due to the flow of water. As the rotor rotates, the magnetic flux changes all the time. Therefore, an alternating voltage is created. With three coils installed, each of them has a separate electrical circuit, and inside it the same variable value appears, where the phase of the voltage is shifted along the circle by one hundred and twenty degrees, that is, by a third relative to the one located nearby.
Maybe power at home as before?
This scheme is called three-phase. But you can safely power the house with the help of one such coil. In this case, the first end of the coil is simply grounded, and the second is led into the house, where this wire is connected, for example, to the kettle plug. The second pin of the plug is grounded. You get the same electricity.
Three-phase current distribution
Three-phase current enters homes through power lines (where the voltage reaches thirty-five kilovolts). It is believed that it is the most economical and more profitable in all respects compared to conventional current.
In industry, power is supplied precisely by three-phase current, soas it is easier to build a rotating structure on it, and in general it is more mobile and has more power.
Wires
Let's figure out what phase, ground and neutral wire are, in more detail.
It is easy to imagine a three-phase generator with a star connection. The phase connection point is called neutral.
Usually it is grounded to increase safety, since if the device fails, then in the absence of grounding, a danger to humans will be created. When you touch the device, it will simply be shocked. But if grounding is present, excess current will leak and there is no risk.
So, all together - neutral wire, ground and phase wires are necessary to ensure the safety of people. New houses under construction have just such a system, while old ones do not.
Phase detection
Sometimes it is necessary to determine where the phase wire is. For an ordinary outlet, this may not be necessary. But when connecting, for example, a chandelier, the phase should be fed directly to the switch, and zero - directly to the lamps. Then, if the light is turned off, when replacing the lamp, a person will not be shocked. And even when the device is turned on, if it accidentally touches the lamp, although it will be hot, it will not hit.
There is a very simple and convenient device for determining phases. It looks like a normal screwdriver. But inside the device has a light bulb, which, when touched, will light up the phase. In this case, the finger should touch the metal at this time.patch of the device.
Some daredevils decide to determine the phase by completely unsafe methods. These include the so-called "control", when the wire is substituted under a stream of water, touched with a neon light or brought into contact with the battery.
Needless to say, it is better not to resort to methods that become dangerous not only for the experimenter, but also for others. Moreover, an indicator screwdriver is currently quite inexpensive.
With proper installation of electrical cables in the premises, a blue wire will mean zero, yellow-green - ground, and black or any other color will indicate a phase. But the work of electricians, unfortunately, is not always conscientious and qualified. Therefore, the colors may not match the purpose.
