All about electricity. Fundamentals of electrical engineering for beginners. Wiring diagrams

Now it is impossible to imagine life without electricity. This is not only lights and heaters, but all electronic equipment from the very first 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 not a single electrician can do without it. It states that current is directly proportional to voltage and inversely proportional to resistance. This means that the higher the voltage applied to the resistance, motor, capacitor or coil (with other conditions 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 the 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 the 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 the power source, and one or more goes out.

Kirchhoff's second law. It is used when connecting several loads in series or a load and a long cable. 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 EMFs is 0.

How to start learning 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 classes. The educational institution also issues a document that will be required 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 that 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 that talk about various practical issues that a novice electrician may encounter, about programs that you have to work with and about equipment installed in residential premises.

Fundamentals of the theory of electrical engineering- 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, wiring diagrams for light bulbs, switches, sockets. Types of tools for electrical installation;
1. Types of materials for electrical installation, electrical circuit assembly;
2. Switch connection and parallel connection;
3. Installation of an electric circuit with a two-gang switch. Model of power supply of the room;
4. Model of power supply of a room with a switch. Fundamentals of safety.

Books

The best adviser there has always been a book. Previously, it was necessary to borrow a book from the library, from friends or buy. Now on the Internet you can find and download a variety of books necessary for a novice or experienced electrician. Unlike video tutorials, where you can see how a particular action is performed, in a book you can keep it nearby while you work. The book may contain reference materials that will not fit in the video lesson (as 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 issues - 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 electrical engineering

books for electrician- this site has a lot of tips for a beginner electrical engineer

electrical specialist- a site for novice electricians and professionals

Electrician's 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:

Beginner electrician course - tutorial in electrical engineering

Basic concepts

Electronics for beginners - initial course and fundamentals of electronics

Safety

The main thing when performing electrical work is to comply with safety regulations. While 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 are working." For a more detailed study of this issue, you need to take the book "Safety regulations for electrical installation and adjustment work."

Before proceeding with work related to electricity, it is necessary to “savvy” a little theoretically in this matter. Simply put, electricity usually refers to the movement of electrons under the action of 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 magnitude in time. Let's say that in a conventional battery there is direct current. Then the charge will flow from minus to plus, not changing until it runs out.

Alternating current- this is a current that changes direction and magnitude with a certain periodicity.

Think of the 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 rises to a maximum, then passes through zero, and then the reverse process occurs, but with a different sign. When asked why this happens and why such a current is needed, it can be answered 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 for power transmission over long distances. With it, less energy is wasted.

With the help of a transformer (a special device in the form of coils), 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 used quite widely - in all types of batteries, in the chemical industry and in 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 what relation they have to the surrounding reality. However, it is a must to know. Without going into technical details that a home master does not need, we can say that a three-phase network is a method of transmitting electric current when alternating current flows through three wires and returns one at a time. The above needs some clarification. Any electrical circuit consists of two wires. One by one, the current goes to the consumer (for example, to a kettle), and by the other it returns back. If such a circuit is opened, 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 wires and one return. This is possible because the phase of the alternating current in each of the three wires is shifted with respect to the neighboring one by 120 ° C. A textbook on electromechanics will help answer this question in more detail. The transmission of alternating current 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 zero. So he gets into apartments and houses. Although sometimes a three-phase network is brought directly into the house. Usually, we are talking about the private sector, and this state of affairs has its pros and cons. This will be discussed later. Earth, or, more correctly, grounding, is the third wire in a single-phase network. In essence, 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 gets out of control (for example, a short circuit), there is a risk of fire or electric shock. To prevent this from happening (that is, the current value should not exceed a level that is safe for humans and devices), grounding is introduced. Through this wire, excess electricity literally goes into the ground.

One more example. Let's say that a small breakdown occurred in the operation of the electric motor of the washing machine and part of the electric current falls on the outer metal shell of the device. If there is no ground, this charge will wander around 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 harming anyone. In addition, we can say that the neutral conductor can also be grounding 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 deal 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 the neutral wire as a ground wire. Never do that. In the event of a break in the neutral wire, the housings of grounded devices will be energized with 220 V.

You can only learn what you love.
Goethe I.

"How to independently study electronics from scratch?" - one of the most popular questions on amateur radio forums. At the same time, the answers that I found when I asked it myself did not help me much. So I decided to give mine.

This essay describes a general approach to self-study, and since it began to receive a lot of views on a daily basis, I decided to develop it and make a small guide to self-study electronics and tell how I do it. Subscribe to the newsletter - it will be interesting!

Creativity and result

To learn something, you need to love it, burn with interest and exercise regularly. It seems that I just voiced a common truth ... Nevertheless. In order to study electronics with ease and pleasure, one must love it and treat it with curiosity and admiration. Now it's common for everyone to be able to send a video message to the other side of the earth and get an instant response. And this is one of the achievements of electronics. 100 years of work of thousands of scientists and engineers.

As we are usually taught

The classical approach that is preached in schools and universities around the world can be called the approach upwards. First, they tell you what an electron, atom, charge, current, resistor, capacitor, inductance are, they make you solve hundreds of problems on finding currents in resistor circuits, then even more difficult, etc. This approach is similar to climbing a mountain. But going uphill is more difficult than going down. And many give up before reaching the top. This is true in any business.

What if you go down the mountain? The main idea is to first get the result, and then analyze in detail why it works the way it does. Those. this is the classic approach of children's radio clubs. It provides an opportunity to get a sense of victory and success, which in turn stimulates the desire to study electronics further. You see, there is very doubtful benefit in studying one theory. It is necessary to practice, since not everything from theory is 100% put into practice.

There's an old engineering joke that goes, "If you're good at math, you should go into electronics." Typical nonsense. Electronics is creativity, novelty of ideas, practice. And it is not necessary to fall into the wilds of theoretical calculations in order to create electronic devices. You can easily master the necessary knowledge on your own. And you will improve mathematics in the process of creativity.

The main thing is to understand the basic principle, and only then the subtleties. This approach just turns the world upside down. self-study. He is not new. This is how artists draw: first a sketch, then detailing. This is how various large systems are designed, etc. This approach is similar to the "poke method", but only if you do not look for an answer, but stupidly repeat the same action.

Did you like the device? Assemble, figure out why it is made that way and what ideas are embedded in its design: why are these parts used, why are they connected in this way, what principles are used? Is it possible to improve something or just replace some part?

Design is creativity, but it can be learned. To do this, you only need to perform simple actions: read, repeat other people's devices, think about the result, enjoy the process, be brave and self-confident.

Mathematics in electronics

In amateur radio design, consider improper integrals unlikely to have to, but knowledge of Ohm's law, Kirchhoff's rules, current / voltage divider formulas, possession of complex arithmetic and trigonometry can come in handy. This is the basics of the basics. If you want to be able to do more - love mathematics and physics. This is not only useful, but also extremely entertaining. Of course, this is not required. You can make pretty cool devices without knowing anything at all. Only these will be devices invented by someone else.

When, after a very long break, I realized that electronics was calling me again and beckoning me into the ranks of radio amateurs, it immediately became clear that my knowledge had long since disappeared, and the availability of components and technologies had become wider. What did I start doing? There was only one way - to recognize yourself as a complete zero and start from nothing: there are no familiar experienced electronic engineers, there is no self-study program either, I discarded the forums because they are a dump of information and take a lot of time (you can find out some question there in short, but it is very difficult to get whole knowledge - everything is so important there that you can burst!)

And then I went the oldest and easiest way: through books. In good books, the topics are discussed most fully and there is no idle chatter. Of course, there are errors in the books, and tongue-tied. You just need to know which books to read and in what order. After reading well-written books, the result will be excellent.

My advice is simple but useful - read books and magazines. For example, I want not only to repeat other people's schemes, but to be able to design my own. Creating is interesting and fun. That's what my hobby should be: interesting and entertaining. Yes, and yours too.

What books will help you learn electronics

I spent a lot of time looking for suitable books. And I realized that I should say thank you to the USSR. Such an array of useful books remained after him! The USSR can be scolded, it can be praised. Looking for what. So, for books and magazines for radio amateurs and schoolchildren, we must thank. The circulation is crazy, the authors are selected. Until now, you can find books for beginners that will give odds to all modern ones. Therefore, it makes sense to go through second-hand bookstores and ask around (and you can download everything).

1. Klimchevsky Ch. - The ABC of a radio amateur.
2. Amish. Electronics? There is nothing easier.
3. B.S. Ivanov. Oscilloscope - your assistant (how to work with an oscilloscope)
4. Khablowski. I. Electronics in questions and answers
5. Nikulin, Povny. Encyclopedia of a beginner radio amateur
6. Revich. Entertaining electronics
7. Shishkov. First steps in radio electronics
8. Koldunov. Amateur radio alphabet
9. Bessonov V.V. Electronics for beginners and beyond
10. V. Novopolsky - Working with an oscilloscope

This is my list of books for the "little ones". Be sure to flip through Radio magazines from the 70s to the 90s. After that, you can already read:

1. Gendin. Design Tips
2. Kaufman, Seedman. Practical guide according to the calculations of circuits in electronics
3. Volovich G. Circuitry of analog and analog-digital electronic devices
4. Tietze, Shenk. Semiconductor circuitry. 12th ed.
5. Shustov M. A. Practical circuitry.
6. Gavrilov S.A.-Semiconductor circuits. Developer Secrets
7. Barnes. Electronic design
8. Milovzorov. Elements of information systems
9. Revich. Practical programming MK AVR
10. Belov. Tutorial on Microprocessor Technology
11. Suematsu. Microcomputer control systems. First meeting
12. Yu.Sato. Signal processing
13. D. Harris, S. Harris. Digital circuitry and computer architecture
14. Jansen. Digital Electronics Course

I think these books will answer a lot of questions. More specialized knowledge can be gleaned from more specialized books: audio amplifiers, microcontrollers, etc.

And of course you need to practice. Without a soldering iron, the whole theory is in the hole. It's like driving a car in your head.
By the way, you can read more detailed reviews of some of the books from the list above.

What else should be done?

Learn to read device schematics! Learn to analyze the circuit and try to understand how the device works. This skill only comes with practice. You need to start with the simplest schemes, gradually increasing the complexity. Thanks to this, you will not only learn the designations of radio elements on the diagrams, but also learn how to analyze them, and also remember the tricks and decisions.

Is electronics expensive?

Unfortunately, money is required! Ham radio is not the cheapest hobby and will require some minimum fin. investments. But you can start with virtually no investment: you can get books from bookcrossings or borrow them from libraries, read them electronically, you can buy the simplest devices for a start, and buy more advanced ones when the capabilities of simple devices are not enough.

Now you can buy everything: an oscilloscope, a generator, a power source and other measuring instruments for a home laboratory - all this should be purchased over time (or do it yourself what you can do at home)

But when you are small and a beginner, you can get by with a finger and parts from broken equipment that someone throws out or just lay around at home for a long time without work. The main thing is to have a desire! And the rest will follow.

What to do if it doesn't work?

Continue! Rarely do things work out well the first time. And it happens that there are no results and no - as if he ran into an invisible barrier. Someone overcomes this barrier in six months or a year, while others only after a few years.

If you encounter difficulties, then you don’t have to tear your hair and think about yourself that you are the dumbest in the world, since Vasya understands what a reverse collector current is, but you still can’t understand why it plays a role. Maybe Vasya is just puffing out his cheeks, but he himself is not boom-boom =)

The quality and speed of self-learning depend not only on personal abilities, but also on the environment. Here it is necessary to rejoice at the existence of forums. They still meet (and often) polite professionals who are happy to teach beginners. (There are all sorts of grimzy, but I consider such people a lost branch of evolution. I feel sorry for them. bending your fingers is the show-off of the lowest level. It’s better to just be silent)

Useful programs

Be sure to familiarize yourself with CAD systems: sketchers of circuit diagrams and printed circuit boards, simulators, useful and convenient programs (Eagele, SprintLayout, etc.). I have dedicated a whole section on the site for them. From time to time there will appear materials on working with programs that I use myself.

And most importantly - experience the joy of creativity from amateur radio! In my opinion, any business should be treated like a game. Then it will be both entertaining and informative.

About practice

Usually every radio amateur always knows what device he wants to make. But if you have not decided yet, then I will advise you to assemble a power source, figure out what it is for and how each part of it works. Then you can turn your attention to amplifiers. And assemble, for example, an audio amplifier.

You can experiment with the simplest electrical circuits: a voltage divider, a diode rectifier, high-frequency / mid-frequency / low-frequency filters, a transistor and single-transistor stages, the simplest digital circuits, capacitors, inductors. All this will be useful in the future, and the knowledge of such basic circuits and components will give confidence in their abilities.

When you go step by step from the simplest to the more complex, then the knowledge overlaps each other in portions and it is easier to master more complex topics. But sometimes it is not clear from which bricks and how the building should be folded. Therefore, sometimes you should do the opposite: set a goal to assemble some kind of device and master a lot of questions when assembling it.

May Om, Ampere and Volt be with you:

» basic fundamentals of general electrical engineering.

Topic: basic fundamentals of general electrical engineering, electrical engineering for a beginner.

Before becoming an electrician, you first need to know theoretical basis electricity work. After all, what is the difference between an electrician and an ordinary person. And the fact that, due to the theory, which over time was reinforced by practical experience, a person from an ordinary “know-nothing person” turns into an experienced electrical engineer who is fully capable of understanding not only faulty electrical devices, but also who will be able to make a home-made “device”. Such an electrician can be entrusted with any business related to his profession, and he can easily cope with this task without much difficulty.

Electrical engineering for beginners is a cognitive path, gradually passing through which a person builds up professional experience. Do not think that after reading a book on the general theory of electrical engineering, you can immediately learn how to do everything. Even knowing “how to do it”, people in most cases are either afraid to start (knowing about the danger of electricity), or they do it so awkwardly and carelessly that later it is better to redo this work in order to avoid emergency consequences associated with the quality of functioning this device, and the potential probability of poor electrical safety.

The basics of general electrical engineering are the basics, telling the student what and how it works in general. For example, a person can be given a ready-made instruction “what and how to do consistently”. A capable person will be able to do a certain work according to this plan, and it will be quite correct. But if such a person has to face a case in which there are some previously unknown points (some electrical equipment suddenly broke down and needs to be quickly repaired), then this situation will cause a slight stupor, fussy behavior, and many incorrect and erroneous actions (and this loss of time, energy and nerves).

Electrical engineering for beginners, namely the basics of general electrical engineering, should begin with the simplest laws of physics (electronics section). It is the responsibility of the beginner to learn what electricity is in general, what its properties are, what danger it carries, protection measures and precautions, and so on. Knowledge of this already gives a general idea of ​​\u200b\u200belectricians, as such. Introducing a person first to difficult-to-understand special subjects (for example, automation, signal theory, etc.), the main thing is missed, namely, the assimilation of basic concepts in a figurative language. A "porridge" is formed in the head from a lot of fragmented knowledge, which is very difficult to collect in general model electricity work even smart.

An important factor that greatly affects the quality of teaching electrical engineering for beginners is interest and practice. What do you think is better for beginners to learn, “dry theory”, or step-by-step training, in which some theoretical knowledge is first given in a small dose, followed by practical consolidation (like in chemistry lessons - they talked about the interaction of substances and showed on illustrative example of how it works). Even having assembled the simplest electrical circuit, consisting of a power source, a light bulb, a switch, a rheostat, meters, a person will immediately feel what's what, than just draw the same thing on the board and dryly talk about the circuit.

P.S. I would advise you to delve more into the basic principles of electricity, knowing and understanding them well, further more complex concepts will be given much easier and clearer. Try to figure out on your own the principles of operation of the simplest circuits and the operation of electrical components. After all, complex circuits are many smaller, simpler circuits combined into one.

We offer a small material on the topic: "Electricity for beginners." It will give an initial idea of ​​the terms and phenomena associated with the movement of electrons in metals.

Term Features

Electricity is the energy of small charged particles moving in conductors in a certain direction.

With direct current, there is no change in its magnitude, as well as the direction of movement for a certain period of time. If a galvanic cell (battery) is chosen as the current source, then the charge moves in an orderly manner: from the negative pole to the positive end. The process continues until it completely disappears.

Alternating current periodically changes the magnitude, as well as the direction of movement.

AC transmission scheme

Let's try to understand what a phase in a word is, everyone has heard it, but not everyone understands its true meaning. We will not go into details and details, we will choose only the material that the home master needs. A three-phase network is a method of transmitting electric current, in which current flows through three different wires, and it returns through one. For example, there are two wires in an electrical circuit.

On the first wire to the consumer, for example, to the kettle, there is a current. The second wire is used for its return. When such a circuit is opened, there will be no passage of an electric charge inside the conductor. This diagram describes a single-phase circuit. in electricity? A phase is a wire through which an electric current flows. Zero is the wire through which the return is made. In a three-phase circuit, there are three phase wires at once.

The electrical panel in the apartment is necessary for the current in all rooms. consider it economically feasible, since they do not need two. When approaching the consumer, the current is divided into three phases, each with zero. The earthing switch, which is used in a single-phase network, does not carry a working load. He is a fuse.

For example, if a short circuit occurs, there is a threat of electric shock, fire. To prevent such a situation, the current value should not exceed a safe level, the excess goes to the ground.

The manual "School for an electrician" will help novice craftsmen to cope with some breakdowns of household appliances. For example, if there are problems with the operation of the electric motor of the washing machine, the current will fall on the outer metal case.

In the absence of grounding, the charge will be distributed throughout the machine. When you touch it with your hands, a person will act as a ground electrode, having received an electric shock. If there is a ground wire, this situation will not occur.

Features of electrical engineering

The manual "Electricity for Dummies" is popular with those who are far from physics, but plan to use this science for practical purposes.

The beginning of the nineteenth century is considered the date of the appearance of electrical engineering. It was at this time that the first current source was created. The discoveries made in the field of magnetism and electricity have managed to enrich science with new concepts and facts of great practical importance.

The "School for an Electrician" manual assumes familiarity with the basic terms related to electricity.

Many collections of physics contain complex electrical circuits, as well as a variety of obscure terms. In order for beginners to understand all the intricacies of this section of physics, a special manual “Electricity for Dummies” was developed. An excursion into the world of the electron must begin with a consideration of theoretical laws and concepts. Illustrative examples, historical facts used in the book "Electricity for Dummies" will help novice electricians learn knowledge. To check progress, you can use tasks, tests, exercises related to electricity.

If you understand that you do not have enough theoretical knowledge to independently cope with the connection of electrical wiring, refer to the manuals for "dummies".

Safety and practice

First you need to carefully study the section on safety. In this case, during work related to electricity, there will be no emergencies hazardous to health.

In order to put into practice the theoretical knowledge gained after self-study of the basics of electrical engineering, you can start with old household appliances. Before starting repairs, be sure to read the instructions that came with the device. Do not forget that electricity is not to be trifled with.

Electric current is associated with the movement of electrons in conductors. If a substance is not capable of conducting current, it is called a dielectric (insulator).

For the movement of free electrons from one pole to another, a certain potential difference must exist between them.

The intensity of the current passing through a conductor is related to the number of electrons passing through the cross section of the conductor.

The current flow rate is affected by the material, length, cross-sectional area of ​​​​the conductor. As the length of the wire increases, its resistance increases.

Conclusion

Electricity is an important and complex branch of physics. The manual "Electricity for Dummies" considers the main quantities that characterize the efficiency of electric motors. Voltage units are volts, current is measured in amperes.

Everyone has a certain amount of power. It refers to the amount of electricity generated by the device in a certain period of time. Energy consumers (refrigerators, washing machines, kettles, irons) also have power, consuming electricity during operation. If desired, you can carry out mathematical calculations, determine the approximate fee for each household appliance.