There are many concepts that you cannot see with your own eyes and touch with your hands. Most a prime example serves as electrical engineering, consisting of complex circuits and poorly understood terminology. Therefore, many people simply retreat before the difficulties of the forthcoming study of this scientific and technical discipline.
The basics of electrical engineering for beginners, outlined by accessible language... Reinforced historical facts and illustrative examples, they become fascinating and understandable even for those who first encountered unfamiliar concepts. Gradually moving from simple to complex, it is quite possible to study the presented materials and use them in practice.
Concepts and properties of electric current
Electrical laws and formulas are required for more than just any calculations. They are also needed by those who, in practice, carry out operations related to electricity. Knowing the basics of electrical engineering, you can logically determine the cause of the malfunction and very quickly eliminate it.
The essence of an electric current is the movement of charged particles that carry an electric charge from one point to another. However, with the random thermal motion of charged particles, like free electrons in metals, no charge transfer occurs. The movement of an electric charge through the cross section of a conductor occurs only under the condition of the participation of ions or electrons in an ordered motion.
Electric current always flows in a certain direction. Its presence is indicated by specific signs:
- Heating the conductor through which the current flows.
- The change chemical composition conductor under the influence of current.
- Exerting a force effect on neighboring currents, magnetized bodies and neighboring currents.
Electric current can be direct or alternating. In the first case, all its parameters remain unchanged, and in the second, the polarity changes periodically from positive to negative. In each half-period, the direction of the electron flow changes. The rate of such periodic changes is the frequency measured in hertz
Basic current values
When an electric current appears in the circuit, there is a constant transfer of charge through the cross-section of the conductor. The amount of charge transferred over a certain unit of time is called, measured in amperes.
In order to create and maintain the movement of charged particles, the effect of a force applied to them in a certain direction is necessary. In case of termination of such action, the flow of electric current also stops. This force is called the electric field, it is also known as. It is she who causes the potential difference or voltage at the ends of the conductor and gives impetus to the movement of charged particles. To measure this value, a special unit is used - volt... There is a certain relationship between the basic quantities, reflected in Ohm's law, which will be considered in detail.
The most important characteristic of a conductor, directly related to an electric current, is resistancemeasured in ohmah... This value is a kind of resistance of the conductor to the flow of electric current in it. As a result of the effect of resistance, the conductor is heated. With an increase in the length of the conductor and a decrease in its cross section, the resistance value increases. A value of 1 Ohm occurs when the potential difference in the conductor is 1 V, and the current is 1 A.
Ohm's law
This law refers to the basic provisions and concepts of electrical engineering. It most accurately reflects the relationship between such quantities as current strength, voltage, resistance, etc. The definitions of these quantities have already been considered, now it is necessary to establish the degree of their interaction and influence on each other.
In order to calculate this or that value, you must use the following formulas:
- Current strength: I \u003d U / R (ampere).
- Voltage: U \u003d I x R (volts).
- Resistance: R \u003d U / I (ohm).
The dependence of these values, for a better understanding of the essence of the processes, is often compared with the hydraulic characteristics. For example, at the bottom of a tank filled with water, a valve is installed with an adjacent pipe. When the valve is opened, water begins to flow because there is a difference between high pressure at the beginning of the pipe and low pressure at the end. Exactly the same situation occurs at the ends of a conductor in the form of a potential difference - a voltage under the influence of which electrons move along the conductor. Thus, by analogy, voltage is a kind of electrical pressure.
The current strength can be compared with the flow rate of water, that is, its amount flowing through the cross section of the pipe for a set period of time. With a decrease in the diameter of the pipe, the water flow will also decrease due to the increase in resistance. This limited flow can be compared to the electrical resistance of a conductor, which keeps the flow of electrons within a certain framework. The interaction of current, voltage and resistance is similar to hydraulic characteristics: with a change in one parameter, all others change.
Energy and power in electrical engineering
In electrical engineering, there are also concepts such as energy and powerrelated to Ohm's law. Energy itself exists in mechanical, thermal, nuclear and electrical forms. In accordance with the law of conservation of energy, it cannot be destroyed or created. It can only transform from one form to another. For example, audio systems convert electricity into sound and heat.
Any electrical appliances consume a certain amount of energy over a set period of time. This value is individual for each device and represents the power, that is, the amount of energy that a particular device can consume. This parameter is calculated by the formula P \u003d I x U, the unit is. It means moving one volt through a one ohm resistance.
Thus, the basics of electrical engineering for beginners will help at first to understand the basic concepts and terms. After that, it will be much easier to use the acquired knowledge in practice.
Electrician for Dummies: Electronics Basics
Now it is impossible to imagine life without electricity. This is not only light and heaters, but the whole electronics from the earliest vacuum tubes to mobile phones and computers. Their work is described by a variety of, sometimes very complex formulas. But even the most complex laws of electrical engineering and electronics are based on the laws of electrical engineering, which in institutes, technical schools and colleges studies the subject "Theoretical Foundations of Electrical Engineering" (TOE).
Basic laws of electrical engineering
- Ohm's law
- Joule-Lenz law
- Kirchhoff's first law
Ohm's law - the study of TOE begins with this law and no electrician can do without it. It states that the current is directly proportional to the voltage and inversely proportional to the resistance.This means that the higher the voltage applied to the resistance, electric motor, capacitor or coil (if other conditions are unchanged), the higher the current flowing through the circuit. Conversely, the higher the resistance, the lower the current.
Joule-Lenz law... Using this law, you can determine the amount of heat released on a heater, cable, electric motor power or other types of work performed by electric current. This law states that the amount of heat generated when an electric current flows through a conductor is directly proportional to the square of the current strength, the resistance of this conductor, and the time the current flows. With the help of this law, the actual power of electric motors is determined, and also on the basis of this law, an electric meter works, according to which we pay for the consumed electricity.
Kirchhoff's first law... With its help, cables and circuit breakers are calculated when calculating power supply schemes. It states that the sum of the currents entering any node is equal to the sum of the currents leaving that node. In practice, one cable comes from a power source, and one or more leaves.
Kirchhoff's second law... It is used when connecting several loads in series or a load and a long male. It is also applicable when connected not from a stationary power source, but from a battery. It states that in a closed circuit, the sum of all voltage drops and all EMF is equal to 0.
How to start studying electrical engineering
It is best to study electrical engineering in special courses or in educational institutions. In addition to the opportunity to communicate with teachers, you can use the material base of the educational institution for practical training. Educational institution also issues a document that will be needed when applying for a job.
If you decide to study electrical engineering on your own or you need additional material for classes, that is, there are many sites where you can study and download the necessary materials to your computer or phone.
Video lessons
There are many videos on the Internet to help you master the basics of electrical engineering. All videos can be watched online or downloaded using special programs.
Electrician video tutorials - a lot of materials telling about various practical issues that a novice electrician may encounter, about programs that have to be worked with and about equipment installed in residential premises.
Fundamentals of Electrical Engineering Theory - here are video tutorials that clearly explain the basic laws of electrical engineering. The total duration of all lessons is about 3 hours.
- zero and phase, connection diagrams of bulbs, switches, sockets. Types of tools for electrical installation;
- Types of materials for wiring, electrical circuit assembly;
- Switch connection and parallel connection;
- Installation of an electrical circuit with a two-button switch. Room power supply model;
- Room power supply model with a switch. Safety basics.
Books
The best advisor there was always a book... Previously, it was necessary to borrow a book from a library, from friends, or buy. Now on the Internet you can find and download a variety of books that are necessary for a novice or experienced electrician. Unlike video tutorials, where you can watch how this or that action is performed, you can keep in the book next to it while doing the work. The book may contain reference materials that will not fit in the video lesson (like in school - the teacher tells the lesson described in the textbook, and these forms of learning complement each other).
There are sites with a large amount of electrical literature on a variety of topics - from theory to reference materials. On all these sites, the desired book can be downloaded to a computer, and later read from any device.
for instance,
mexalib - various kinds of literature, including on electrical engineering
books for electrician - this site has a lot of tips for a beginner electrical engineer
electrician - site for beginner electricians and professionals
Electrician library - many different books mainly for professionals
Online tutorials
In addition, there are online textbooks on electrical engineering and electronics with an interactive table of contents on the Internet.
These are such as:
Electrician Basic Course - tutorial in electrical engineering
Basic concepts
Electronics for beginners - initial course and electronics fundamentals
Safety engineering
The main thing when performing electrical work is compliance with safety measures. If improper operation can lead to equipment failure, failure to follow safety precautions can result in injury, disability or death.
Main rules - this is not to touch live wires with bare hands, to work with a tool with insulated handles and when the power is turned off, to hang out a poster “do not turn on, people work”. For a more detailed study of this issue, you need to take the book "Safety rules for electrical installation and commissioning."
Speaking about the property of this or that body to prevent the passage of electric current through it, we usually use the term "electrical resistance". In electronics, it is convenient, there are even special microelectronic components, resistors that have one or another nominal resistance.But there is also the concept of "electrical conductivity" or "electrical conductivity", which characterizes the body's ability to conduct electric current. Whereas resistance is inversely proportional to current, conductance is directly proportional to current ...
Latin word Polus comes from the Greek for stripes. In a broad sense, this term denotes the limit, boundary or extreme point of something, something one, diametrically opposite to the other, when it comes to, for example, two poles.Our planet has north and south geographic poles - the opposite edges of the globe relative to the equator, as well as magnetic poles (like a permanent magnet). A permanent magnet has a north and south pole - they tend to be attracted to each other. In the same way, the poles of the current source indicate its peculiar boundaries ...
The amount of current flowing through a conductor is directly proportional to the voltage at its ends. This means that the greater the voltage at the ends of the conductor, the greater the current in this conductor. But with the same voltage across different conductors made of different materials, the current will be different. That is, if the voltage on different conductors is increased in the same way, then the increase in the magnitude of the current will occur in different conductors in different ways, and this depends on the properties of a particular conductor.For any conductor, the dependence of the current value on the applied voltage is individual ...
To measure the magnitude of the current in the DC and AC circuits, an electrical measuring device is used, an ammeter. The ammeter is connected in series with the current source.Since the current is the ordered movement of charged particles along the conductor (through the cross-section of the conductor), to measure its value, it is necessary to pass the measured current through an ammeter as well. Therefore, the ammeter is included precisely in the break of the circuit under study, when it is necessary to measure the current, and in no case parallel to it.The output circuit of a modern ammeter usually contains a shunt ...
To measure AC or DC voltage in AC and DC circuits, a device called a voltmeter is used. Since voltage is present between different points of the circuit or at the poles of the voltage source, the voltmeter is always connected in parallel with the investigated section of the circuit or parallel to the terminals of the voltage source.You can, of course, turn on the voltmeter in series, in the open circuit, but then the voltage of the source will be measured, and not at the section of the circuit, since the circuit will be open, and the voltmeter itself has a very large internal resistance ...
An LED lamp is a light source based on LEDs. LEDs are special semiconductor devices that are designed specifically to receive light when an electric current passes through them. Unlike incandescent bulbs, LED bulbs are more efficient. And while an incandescent lamp converts about 5-10% of the electrical energy supplied to it into light, an LED lamp has an efficiency of about 50%. In principle, LEDs are 10 times superior in luminous efficiency to incandescent lamps.LEDs require low voltage for their power supply ...
The capacitor is intended for temporary storage of electrical energy in the form of potential energy separated in space of positive and negative electric charges, that is, in the form of an electric field in the space between them. Accordingly, an electric capacitor includes three main components: two conducting plates, on which separated charges are located in a charged capacitor, and a dielectric layer located between the plates.Capacitor plates, depending on the type of this electrical product ...
Although not every substance can be used to make a permanent magnet, all substances are magnetized in one way or another when placed in an external magnetic field. Some of the substances are more magnetized, and some are so weak that it cannot be noticed without special devices.When we say "the substance has been magnetized", we mean the fact that the substance itself became a source of the magnetic field due to the influence of external magnetic field... That is, the parameters of the magnetic induction vector B in the presence of this substance in a given space do not correspond to the magnetic induction vector ...
At an equal temperature of metal conductors in contact in a closed circuit, the contact potential difference at the boundaries between them will not create any current in the circuit, it will only balance the oppositely directed flows of electrons.Having calculated the algebraic sum of the potential differences between the contacts, it is easy to understand that it vanishes. Therefore, in this case, there will be no EMF in the circuit. But what if the contact temperatures are different? Let's say contacts C and D are at different temperatures. What then? Let's assume that the work function of electrons ...
Let's do this thought experiment... Imagine that there is a certain village at a distance of 100 kilometers from the city, and that a wire signal line about 100 kilometers long with a light bulb at the end is laid from the city to this village. Shielded two-wire line, it is laid on supports along the road. And if we now send a signal along this line from city to village, then after what time will it be received there? Calculations and experience tell us that a signal in the form of an illuminated light bulb will appear ...
Before embarking on work related to electricity, you need a little theoretical knowledge of this issue. Simply put, electricity usually means this movement of electrons under the influence electromagnetic field... The main thing is to understand that electricity is the energy of the smallest charged particles that move inside the conductors in a certain direction.
D.C practically does not change its direction and value over time. Let's say there is a constant current in an ordinary battery. Then the charge will flow from minus to plus without changing until it dries up.
Alternating current - this is a current that changes the direction of movement and magnitude at regular intervals.
Think of a current as a stream of water flowing through a pipe. After a certain period of time (for example, 5 s), the water will rush in one direction, then in the other. With current, this happens much faster - 50 times per second (frequency 50 Hz). During one period of oscillation, the current value rises to a maximum, then passes through zero, and then the opposite process occurs, but with a different sign. When asked why this is happening and why such a current is needed, one can answer that receiving and transmitting alternating current is much easier than direct current.
Receiving and transmitting alternating current is closely related to a device such as a transformer. A generator that produces alternating current is much simpler in design than a direct current generator. In addition, alternating current is best suited to transmit power over long distances. With its help, less energy is lost.
Using a transformer (a special device in the form of coils), the alternating current is converted from low voltage to high voltage and vice versa, as shown in the illustration. It is for this reason that most devices operate on a network in which the current is alternating. However, direct current is also widely used - in all types of batteries, in the chemical industry and some other areas.
Many have heard such mysterious words as one phase, three phases, zero, ground or earth, and they know that these are important concepts in the world of electricity. However, not everyone understands what they mean and how they relate to the surrounding reality. Nevertheless, it is imperative to know. Without going into technical details that are not needed by a home craftsman, we can say that a three-phase network is a way of transmitting electric current when an alternating current flows through three wires and returns one by one. The above needs to be explained a little. Any electrical circuit consists of two wires. One by one, the current goes to the consumer (for example, to the kettle), and the other goes back. If you open such a circuit, then the current will not flow. That's the whole description of a single-phase circuit.
The wire through which the current flows is called phase, or simply phase, and through which it returns - zero, or zero. A three-phase circuit consists of three phase conductors and one return conductor. This is possible because the AC phase in each of the three wires is shifted with respect to the adjacent one by 120 ° C. A textbook on electromechanics will help answer this question in more detail. AC transmission occurs precisely with the help of three-phase networks. This is economically beneficial - two more neutral wires are not needed.
Approaching the consumer, the current is divided into three phases, and each of them is given a zero. So he gets into apartments and houses. Although sometimes a three-phase network is brought directly into the house. As a rule, we are talking about the private sector, and this state of affairs has its pros and cons. This will be discussed later. Ground, or, more correctly, grounding is the third wire in a single-phase network. In fact, it does not carry a workload, but serves as a kind of fuse. This can be explained with an example. In the event that electricity goes out of control (for example, a short circuit), there is a danger of fire or electric shock. To prevent this from happening (that is, the value of the current should not exceed a level safe for humans and devices), grounding is introduced. Through this wire, the excess electricity literally goes into the ground.
One more example. Suppose a small breakdown occurs in the operation of the electric motor of the washing machine and part of the electric current enters the outer metal shell of the appliance. If there is no grounding, this charge will continue to wander through the washing machine. When a person touches it, he will instantly become the most convenient outlet for this energy, that is, he will receive an electric shock. If there is a ground wire in this situation, the excess charge will drain through it without causing harm to anyone. In addition, we can say that the neutral conductor can also be ground and, in principle, it is, but only at a power plant. The situation when there is no grounding in the house is unsafe. How to cope with it without changing all the wiring in the house will be described later.
Attention!
Some craftsmen, relying on basic knowledge of electrical engineering, install a neutral wire as a ground wire. Never do that. If the neutral wire breaks, the cases of grounded devices will be energized by 220 V.
Currently, it has already developed quite steadily service market, including in the area household electrics.
Highly professional electricians, with undisguised enthusiasm, do their best to help the rest of our population, while receiving great satisfaction from quality work and modest remuneration. In turn, our population also gets great pleasure from high-quality, fast and completely inexpensive solutions to their problems.
On the other hand, there has always been a fairly wide category of citizens who, in principle, consider it an honor - with my own hand solve absolutely any everyday issues arising on the territory of your own place of residence. Such a position certainly deserves both approval and understanding.
Moreover, all these Substitutions, transfers, installations - switches, sockets, automatic machines, meters, lamps, connecting kitchen ovens and so on - all these types of services most demanded by the population, from the point of view of a professional electrician, at all are not difficult work.
And in truth, an ordinary citizen, without an electrical engineering education, but having sufficiently detailed instructions, may well cope with its implementation himself, with his own hands.
Of course by doing similar work for the first time, a novice electrician can spend much more time than an experienced professional. But it is not at all a fact that this will make it less efficient, with attention to detail and the absence of any rush.
Initially, this site was conceived as a collection of similar instructions regarding the most common problems in this area. But in the future, for people who have absolutely never faced the solution of such issues, a course of "young electrician" of 6 practical lessons was added.
Features of mounting electrical outlets of hidden and exposed wiring. Sockets for an electric cooker. Connecting an electric stove with your own hands.
Switches.
Replacement, installation of electrical switches, hidden and exposed wiring.
Automatic devices and RCDs.
The principle of operation of protective devices and circuit breakers. Classification of circuit breakers.
Electric meters.
Instructions for self-installation and connection of a single-phase meter.
Replacement of wiring.
Indoor electrical installation. Features of installation, depending on the material of the walls and the type of their decoration. Electrical wiring in a wooden house.
Lamps.
Installation of wall lamps. Chandeliers. Installation of spotlights.
Contacts and connections.
Some of the most common types of wire connections found in home electrics.
Electrical Engineering - Theory Basics.
Electrical resistance concept. Ohm's law. Kirchhoff's laws. Parallel and serial connection.
Description of the most common wires and cables.
Illustrated instructions for working with a digital universal electrical measuring device.
About lamps - incandescent, fluorescent, LED lamps.
About the "money."
The profession of an electrician was definitely not considered prestigious until recently. But could it be called low-paid? Below, you can see the price list of the most common services three years ago.
Electrical installation - prices.
Electric meter pcs. - 650p.
Single-pole circuit breakers pcs. - 200p.
Three-pole circuit breakers pcs. - 350p.
Difautomat pcs. - 300p.
RCD single-phase pcs. - 300p.
One-key switch pcs. - 150p.
Two-button switch pcs. - 200p.
Three-button switch pcs. - 250p.
Open wiring board up to 10 groups pcs. - 3400p.
Concealed wiring board up to 10 groups pcs. - 5400p.
Laying of open wiring PM - 40p.
Wiring in the corrugation PM - 150p.
Slitting in the wall (concrete) L.m - 300p.
(brick) L.m. - 200p.
Installation of box and junction box in concrete pcs. - 300p.
brick pcs. - 200p.
drywall pcs. - 100p.
Sconces pcs. - 400p.
Spot light pcs. - 250p.
Hook chandelier pcs. - 550p.
Ceiling chandelier (without assembly) pcs. - 650p.
Setting the bell and bell button pcs. - 500p.
Installation of an outlet, open wiring switch pcs. - 300p.
Installation of a socket, a hidden wiring switch (without installing a socket box) pcs. - 150p.
When I was an electrician "according to an ad", I was unable to mount more than 6-7 points (sockets, switches) of hidden wiring, on concrete - in one evening. Plus, there are 4-5 meters of groove (for concrete). We carry out simple arithmetic calculations: (300 + 150) * 6 \u003d 2700p. - these are sockets with switches.
300 * 4 \u003d 1200r. - this is for strobes.
2700 + 1200 \u003d 3900r. is the total amount.
Not bad for 5-6 hours of work, isn't it? Prices, of course, are Moscow ones; in Russia they will be less, but no more than twice.
Generally speaking, the monthly earnings of an electrician - installer, now rarely exceed 60,000 rubles (not in Moscow)
Of course, there are also especially gifted people in this field (as a rule, with iron health) and practical sense. Under certain conditions, they manage to raise their earnings to 100,000 rubles and above. As a rule, they are licensed to perform electrical work and work directly with the customer, taking "serious" contracts without the participation of various intermediaries.
Electricians - repairers equipment (at enterprises), electricians - high voltage, as a rule (not always) - earn a little less. If the enterprise is profitable and funds are invested in "re-equipment" for electricians-repairmen, additional sources of income may open up, for example, the installation of new equipment during off-hours.
Highly paid but physically difficult and sometimes very dusty, the work of an electrician-installer is undoubtedly worthy of all respect.
Being engaged in electrical installation, a novice specialist can master basic skills and abilities, gain initial experience.
Regardless of how he will build his career in the future, you can be sure that the practical knowledge gained in this way will definitely come in handy.
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