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Electrical diagram- this is a text that describes with certain symbols the content and operation of an electrical device or a set of devices, which allows this text to be expressed in a concise form.

In order to read any text, you need to know the alphabet and reading rules. So, to read diagrams, you should know the symbols - conventions and rules for deciphering their combinations.

The basis of any electrical circuit is graphic symbols various elements and devices, as well as connections between them. The language of modern circuits emphasizes in symbols the main functions that the depicted element performs in the circuit. All correct conventional graphic symbols of electrical circuit elements and their individual parts are given in the form of tables in the standards.

Conventional graphic symbols are formed from simple geometric shapes: squares, rectangles, circles, as well as from solid and dashed lines and dots. Their combination according to a special system, which is provided by the standard, makes it possible to easily depict everything that is required: various electrical devices, instruments, electrical machines, mechanical and electrical connection lines, types of winding connections, type of current, nature and methods of regulation, etc.

In addition, in the conventional graphic symbols on electrical circuit diagrams, special symbols are additionally used to explain the operating features of a particular circuit element.

For example, there are three types of contacts - normally open, normally closed and switching. Legend reflect only the main function of the contact - closing and opening the circuit. To specify additional functionality For a specific contact, the standard provides for the use of special signs applied to the image of the moving part of the contact. Additional signs allow you to find contacts, time relays, limit switches, etc. on the diagram.

Individual elements on electrical diagrams have not one, but several designation options on the diagrams. For example, there are several equivalent options for designating switching contacts, as well as several standard designations for transformer windings. Each of the designations can be used in certain cases.

If the standard does not contain the required designation, then it is compiled based on the principle of operation of the element, designations adopted for similar types of devices, devices, machines in compliance with the design principles stipulated by the standard.

Standards. Conventional graphic symbols on electrical and automation diagrams:

GOST 2.710-81 Alphanumeric designations in electrical circuits:

Reading diagrams is impossible without knowledge of the conventional graphic and letter designations of the elements. Most of them are standardized and described in regulatory documents. Most of them were published in the last century and new standard only one was adopted, in 2011 (GOST 2-702-2011 ESKD. Rules for the execution of electrical circuits), so sometimes a new element base is designated according to the principle “as who came up with it.” And this is the difficulty of reading circuit diagrams of new devices. But, basically, the symbols in electrical circuits are described and are well known to many.

Two types of symbols are often used on diagrams: graphic and alphabetic, and denominations are also often indicated. From this data, many can immediately tell how the scheme works. This skill is developed over years of practice, and first you need to understand and remember the symbols in electrical circuits. Then, knowing the operation of each element, you can imagine the final result of the device.

For composing and reading various schemes Usually different elements are required. There are many types of circuits, but in electrical engineering the following are usually used:

There are many other types of electrical circuits, but they are not used in home practice. The exception is the route of cables passing through the site and the supply of electricity to the house. This type of document will definitely be needed and useful, but it is more of a plan than an outline.

Basic images and functional features

Switching devices (switches, contactors, etc.) are built on contacts of various mechanics. There are make, break and switch contacts. NO contact in in good condition is open, when it is put into operation, the circuit closes. The break contact is normally closed, but under certain conditions it operates, breaking the circuit.

The switching contact can be two or three position. In the first case, first one circuit works, then another. The second one has a neutral position.

In addition, contacts can perform different functions: contactor, disconnector, switch, etc. All of them also have a symbol and are applied to the corresponding contacts. There are functions that are performed only by moving contacts. They are shown in the photo below.

Basic functions can only be performed by fixed contacts.

Symbols for single line diagrams

As has already been said, single-line diagrams indicate only the power part: RCDs, automatic devices, automatic circuit breakers, sockets, circuit breakers, switches, etc. and connections between them. The designations of these conventional elements can be used in electrical panel diagrams.

The main feature of graphic symbols in electrical circuits is that devices similar in principle of operation differ in some small detail. For example, a machine (circuit breaker) and a switch differ only in two small details - the presence/absence of a rectangle on the contact and the shape of the icon on the fixed contact, which display the functions of these contacts. The only difference between a contactor and a switch designation is the shape of the icon on the fixed contact. It's a very small difference, but the device and its functions are different. You need to look closely at all these little things and remember them.

There is also a small difference between the symbols of the RCD and the differential circuit breaker. It also only functions as moving and fixed contacts.

The situation is approximately the same with relay and contactor coils. They look like a rectangle with small graphic additions.

In this case, it’s easier to remember, since there are quite serious differences in appearance additional icons. With a photo relay it’s so simple - the rays of the sun are associated with the arrows. A pulse relay is also quite easy to distinguish by the characteristic shape of the sign.

A little easier with lamps and connections. They have different “pictures”. A detachable connection (such as a socket/plug or socket/plug) looks like two brackets, and a detachable connection (such as a terminal block) looks like circles. Moreover, the number of pairs of checkmarks or circles indicates the number of wires.

Image of tires and wires

In any circuit there are connections and for the most part they are made by wires. Some connections are buses - more powerful conductor elements from which taps can extend. Wires are indicated by a thin line, and branches/connections are indicated by dots. If there are no points, it is not a connection, but an intersection (without an electrical connection).

There are separate images for buses, but they are used if they need to be graphically separated from communication lines, wires and cables.

On wiring diagrams it is often necessary to indicate not only how the cable or wire runs, but also its characteristics or installation method. All this is also displayed graphically. This is also necessary information for reading drawings.

How switches, switches, sockets are depicted

There are no standards-approved images for some types of this equipment. So, dimmers (light regulators) and push-button switches remained without designation.

But all other types of switches have their own symbols in electrical diagrams. They are open and hidden installation, accordingly, there are also two groups of icons. The difference is the position of the line on the key image. In order to understand in the diagram what type of switch we are talking about, this must be remembered.

There are separate designations for two-key and three-key switches. In the documentation they are called “twin” and “twin”, respectively. There are differences for cases with different degrees of protection. In rooms with normal operating conditions, switches with IP20, maybe up to IP23, are installed. In wet rooms (bathroom, swimming pool) or outdoors, the degree of protection should be at least IP44. Their images differ in that the circles are filled in. So it's easy to distinguish them.

There are separate images for the switches. These are switches that allow you to control turning the light on/off from two points (there are also three, but without standard images).

The same trend is observed in the designations of sockets and socket groups: there are single, double sockets, and there are groups of several pieces. Products for rooms with normal operating conditions (IP from 20 to 23) have an unpainted middle; for wet rooms with increased protection housing (IP44 and higher), the middle is tinted dark.

Symbols in electrical diagrams: sockets different types installation (open, hidden)

Having understood the logic of the notation and remembering some initial data (what is the difference between conventional image open and hidden sockets, for example), after a while you will be able to confidently navigate the drawings and diagrams.

Lamps on diagrams

This section describes the symbols in the electrical circuits of various lamps and fixtures. Here the situation with the designations of the new element base is better: there are even signs for LED lamps and lamps, compact fluorescent lamps(housekeeper). It’s also good that the images of lamps of different types differ significantly - it’s difficult to confuse them. For example, lamps with incandescent lamps are depicted in the form of a circle, with long linear fluorescent lamps - a long narrow rectangle. The difference in the image of a linear fluorescent lamp and an LED lamp is not very big - only dashes at the ends - but even here you can remember.

The standard even has symbols in electrical diagrams for ceiling and pendant lamp(cartridge). They also have quite unusual shape- circles of small diameter with dashes. In general, this section is easier to navigate than others.

Elements of electrical circuit diagrams

Schematic diagrams of devices contain a different element base. Communication lines, terminals, connectors, light bulbs are also depicted, but in addition there is a large number of radioelements: resistors, capacitors, fuses, diodes, thyristors, LEDs. Most of the symbols in the electrical circuits of this element base are shown in the figures below.

Rarer ones will have to be looked for separately. But most circuits contain these elements.

Letter symbols in electrical diagrams

Except graphic images elements on the diagrams are signed. It also helps to read the diagrams. Next to the letter designation of an element there is often its serial number. This is done so that later it is easy to find the type and parameters in the specification.

The table above shows international designations. There is also a domestic standard - GOST 7624-55. Excerpts from there with the table below.

Any electrical circuits can be presented in the form of drawings (circuit and wiring diagrams), the design of which must comply with ESKD standards. These standards apply to both electrical wiring or power circuits and electronic devices. Accordingly, in order to “read” such documents, it is necessary to understand the symbols in electrical circuits.

Regulations

Taking into account the large number of electrical elements, a number of normative documents have been developed for their alphanumeric (hereinafter referred to as BO) and conventional graphic designations (UGO) to eliminate discrepancies. Below is a table showing the main standards.

Table 1. Graphic designation standards individual elements in installation and circuit diagrams.

GOST number	Short description
2.710 81	IN this document GOST requirements for BO of various types of electrical elements, including electrical appliances, have been collected.
2.747 68	Requirements for the dimensions of displaying elements in graphical form.
21.614 88	Accepted codes for electrical and wiring plans.
2.755 87	Display of switching devices and contact connections on diagrams
2.756 76	Standards for sensing parts of electromechanical equipment.
2.709 89	This standard regulates the standards in accordance with which contact connections and wires are indicated on diagrams.
21.404 85	Schematic symbols for equipment used in automation systems

It should be taken into account that the element base changes over time, and accordingly changes are made to regulatory documents, although this process is more inert. Let's give a simple example: RCDs and automatic circuit breakers have been widely used in Russia for more than a decade, but there is still no single standard according to GOST 2.755-87 for these devices, unlike circuit breakers. It is quite possible that this issue will be resolved in the near future. To keep abreast of such innovations, professionals monitor changes in regulatory documents; amateurs do not have to do this; it is enough to know the decoding of the main symbols.

Types of electrical circuits

In accordance with ESKD standards, diagrams mean graphic documents on which, using accepted notations, the main elements or components of a structure, as well as the connections connecting them, are displayed. According to the accepted classification, there are ten types of circuits, of which three are most often used in electrical engineering:

If the diagram shows only the power part of the installation, then it is called single-line; if all elements are shown, then it is called complete.

If the drawing shows the wiring of the apartment, then the locations lighting fixtures, sockets and other equipment are indicated on the plan. Sometimes you can hear such a document called a power supply diagram; this is incorrect, since the latter shows how consumers are connected to a substation or other power source.

Having dealt with the electrical circuits, we can move on to the designations of the elements indicated on them.

Graphic symbols

Each type of graphic document has its own designations, regulated by relevant regulatory documents. Let us give as an example the basic graphic symbols for different types electrical diagrams.

Examples of UGO in functional diagrams

Below is a picture depicting the main components of automation systems.

Examples of symbols for electrical appliances and automation equipment in accordance with GOST 21.404-85

Description of symbols:

• A – Basic (1) and acceptable (2) images of devices that are installed outside the electrical panel or junction box.
• B - The same as point A, except that the elements are located on the remote control or electrical panel.
• C - Display actuators(THEM).
• D – Influence of MI on the regulating body (hereinafter referred to as RO) when the power is turned off:

1. RO opening occurs
2. Closing RO
3. The position of the RO remains unchanged.

• E - IM, on which a manual drive is additionally installed. This symbol may be used for any RO provisions specified in paragraph D.
• F- Accepted mappings of communication lines:

1. General.
2. There is no connection at the intersection.
3. The presence of a connection at the intersection.

UGO in single-line and complete electrical circuits

There are several groups of symbols for these schemes; we present the most common of them. To obtain complete information, please refer to the regulatory documents, numbers state standards will be given for each group.

Power supplies.

To designate them, the symbols shown in the figure below are used.

UGO power supplies on schematic diagrams (GOST 2.742-68 and GOST 2.750.68)

Description of symbols:

• A is a constant voltage source, its polarity is indicated by the symbols “+” and “-”.
• B – electricity icon indicating alternating voltage.
• C is a symbol of alternating and direct voltage, used in cases where the device can be powered from any of these sources.
• D – Display of battery or galvanic power source.
• E- Symbol of a battery consisting of several batteries.

Communication lines

The basic elements of electrical connectors are presented below.

Designation of communication lines on circuit diagrams (GOST 2.721-74 and GOST 2.751.73)

Description of symbols:

• A – General mapping adopted for various types electrical connections.
• B – Current-carrying or grounding bus.
• C – Designation of shielding, can be electrostatic (marked with the symbol “E”) or electromagnetic (“M”).
• D - Grounding symbol.
• E – Electrical connection with the device body.
• F – On complex schemes, from several components, thus indicating a broken connection, in such cases “X” is information about where the line will be continued (as a rule, the element number is indicated).
• G – Intersection with no connection.
• H – Joint at intersection.
• I – Branches.

Designations of electromechanical devices and contact connections

Examples of the designation of magnetic starters, relays, as well as contacts of communication devices can be seen below.

UGO adopted for electromechanical devices and contactors (GOSTs 2.756-76, 2.755-74, 2.755-87)

Description of symbols:

• A – symbol of the coil of an electromechanical device (relay, magnetic starter, etc.).
• B – UGO of the receiving part of the electrothermal protection.
• C – display of the coil of a device with mechanical interlock.
• D – contacts of switching devices:

1. Closing.
2. Disconnecting.
3. Switching.

• E – Symbol for designating manual switches (buttons).
• F – Group switch (switch).

UGO of electric machines

Here are a few examples of displays electric machines(hereinafter referred to as EM) in accordance with the current standard.

Designation of electric motors and generators on circuit diagrams (GOST 2.722-68)

Description of symbols:

• A – three-phase EM:

1. Asynchronous (squirrel-cage rotor).
2. Same as point 1, only in two-speed version.
3. Asynchronous electric motors with phase-phase rotor design.
4. Synchronous motors and generators.

• B – Collector, DC powered:

1. EM with permanent magnet excitation.
2. EM with excitation coil.

UGO transformers and chokes

Examples of graphic symbols for these devices can be found in the figure below.

Correct designations of transformers, inductors and chokes (GOST 2.723-78)

Description of symbols:

• A – This graphic symbol can indicate inductors or windings of transformers.
• B – Choke, which has a ferrimagnetic core (magnetic core).
• C – Display of a two-coil transformer.
• D – Device with three coils.
• E - Autotransformer symbol.
• F – Graphic display of CT (current transformer).

Designation of measuring instruments and radio components

A brief overview of the UGO of these electronic components is shown below. For those who want to become more familiar with this information, we recommend viewing GOSTs 2.729 68 and 2.730 73.

Examples of symbolic graphic symbols of electronic components and measuring instruments

Description of symbols:

1. Electricity meter.
2. Picture of an ammeter.
3. Device for measuring network voltage.
4. Thermal sensor.
5. Fixed value resistor.
6. Variable resistor.
7. Capacitor (general designation).
8. Electrolytic capacity.
9. Diode designation.
10. Light-emitting diode.
11. Image of a diode optocoupler.
12. UGO transistor (in this case npn).
13. Fuse designation.

UGO lighting devices

Let's consider how to schematic diagram electric lamps are displayed.

Description of symbols:

• A – General image of incandescent lamps (LN).
• B - LN as a signaling device.
• C – Typical designation of gas-discharge lamps.
• D – Gas discharge light source high blood pressure(the figure shows an example of a design with two electrodes)

Designation of elements in the electrical wiring diagram

Concluding the topic of graphic symbols, we give examples of displaying sockets and switches.

How sockets of other types are depicted is easy to find in the regulatory documents that are available on the Internet.

They are built on the basis of contact symbols: making (Fig. 1, b), breaking (c, d) and switching (d, f). Contacts that simultaneously close or open two circuits are designated as shown in Fig. 1, (w, and and).

The initial position of the closing contacts on electrical circuits is taken to be the open state of the switched electrical circuit, opening - closed, switching - a position in which one of the circuits is closed, the other is open (with the exception of contact with the neutral position). The UGO of all contacts can only be depicted in a mirrored or rotated 90° position.

The standardized UGO system provides for the reflection of such design features, such as the non-simultaneous operation of one or more contacts in a group, the absence or presence of their fixation in one of the positions.

So, if it is necessary to show that the contact closes or opens earlier than others, the symbol of its moving part is supplemented with a short stroke directed towards the operation (Fig. 2, a, b), and if later, with a stroke directed towards reverse side(Fig. 2, c, d).

The absence of fixation in the closed or open positions (self-return) is indicated by a small triangle, the apex of which is directed towards the initial position of the moving part of the contact (Fig. 2, e, f), and fixation is indicated by a circle on the symbol of its fixed part (Fig. 2, g, And).

The last two UGOs on electrical diagrams are used in cases where it is necessary to show a type of switching product whose contacts usually do not possess these properties.

The conventional graphic designation of switches on electrical diagrams (Fig. 3) is based on the symbols of the making and breaking contacts. This means that the contacts are fixed in both positions, i.e., they do not have self-return.

Rice. 3.

The letter code of products in this group is determined by the switched circuit and the design of the switch. If the latter is placed in the control, signaling, measurement circuit, it is designated Latin letter S, and if in the power circuit - the letter Q. The control method is reflected in the second letter of the code: push-button switches and switches are designated by the letter B (SB), automatic ones - by the letter F (SF), all others - by the letter A (SA).

If the switch has several contacts, the symbols of their moving parts on the electrical diagrams are placed in parallel and connected by a mechanical connection line. As an example in Fig. Figure 3 shows a conventional graphic designation of switch SA2, containing one break and two make contacts, and SA3, consisting of two make contacts, one of which (right in the figure) closes later than the other.

Switches Q1 and Q2 are used to switch power circuits. The Q2 contacts are mechanically connected to some control, as evidenced by the dashed line segment. When displaying contacts in different areas diagrams that they belong to one switching product are traditionally reflected in (SA 4.1, SA4.2, SA4.3).

Rice. 4.

Similarly, based on the symbol of the switching contact, symbolic graphic symbols of two-position switches are built on electrical diagrams (Fig. 4, SA1, SA4). If the switch is fixed not only in the extreme, but also in the middle (neutral) position, the symbol of the moving part of the contact will be placed between the symbols of the fixed parts, the possibility of turning it in both directions is shown by a dot (SA2 in Fig. 4). The same is done if it is necessary to show on the diagram a switch that is fixed only in the middle position (see Fig. 4, SA3).

Distinctive feature of UGO push-button switches and switches - a button symbol connected to the designation of the moving part of the contact by a mechanical connection line (Fig. 5). Moreover, if the conventional graphic designation is based on the main contact symbol (see Fig. 1), this means that the switch (switch) is not fixed in the pressed position (when the button is released, it returns to its original position).

Rice. 5.

Rice. 6.

If it is necessary to show fixation, use symbols of contacts with fixation specially designed for this purpose (Fig. 6). Return to the original position when pressing another switch button is shown in this case by the symbol of the locking mechanism, attaching it to the symbol of the moving part of the contact on the side opposite to the button symbol (see Fig. 6, SB1.1, SB 1.2). If the return occurs when the button is pressed again, the sign of the locking mechanism is depicted instead of the mechanical connection line (SB2).

(for example, biscuits) are designated as shown in Fig. 7. Here SA1 (for 6 positions and 1 direction) and SA2 (for 4 positions and 2 directions) are switches with leads from moving contacts, SA3 (for 3 positions and 3 directions) - without leads from them. The conventional graphic designation of individual contact groups is depicted in the same position on the diagrams; belonging to one switch is traditionally shown in the position designation (see Fig. 7, SA1.1, SA1.2).

Rice. 7.

Rice. 8

To depict multi-position switches with complex switching, GOST provides several methods. Two of them are shown in Fig. 8. Switch SA1 - 5 positions (they are indicated by numbers; letters a-d included for clarification only). In position 1, chains a and b, d and d are connected to each other, in positions 2, 3, 4 - chains b and d, a and c, a and d, respectively, in position 5 - chains a and b, c and d .

Switch SA2 - 4 positions. In the first of them, chains a and b are closed (this is indicated by the dots located under them), in the second - chains c and d, in the third - c and d, in the fourth - b and d.

Zorin A. Yu.

Almost all electronic devices, all radio electronics and electrical engineering products manufactured by industrial organizations and enterprises, home craftsmen, young technicians and radio amateurs, contain a certain amount of various purchased electronic components and elements produced mainly by domestic industry. But recently there has been a tendency to use electronic components and components of foreign production. These include, first of all, PPPs, capacitors, resistors, transformers, chokes, electrical connectors, batteries, HIT, switches, installation products and some other types of electronic devices.

The purchased components used or self-manufactured electrical electronic components are necessarily reflected in the circuit and installation electrical diagrams of devices, in drawings and other technical documentation, which are carried out in accordance with the requirements of ESKD standards.

Particular attention is paid to electrical circuit diagrams, which determine not only the basic electrical parameters, but also all the elements included in the device and the electrical connections between them. To understand and read electrical circuit diagrams, you must carefully familiarize yourself with the elements and components included in them, know exactly the scope of application and the principle of operation of the device in question. As a rule, information about the electrical power used is indicated in reference books and specifications - a list of these elements.

The connection between the list of ERE components and their graphic symbols is carried out through positional designations.

To construct conventional graphic symbols of ERE, standardized geometric symbols are used, each of which is used separately or in combination with others. Moreover, the meaning of each geometric image in a symbol in many cases depends on what other geometric symbol it is used in combination with.

The standardized and most frequently used graphic symbols of ERE in electrical circuit diagrams are shown in Fig. 1. 1. These designations apply to all components of the circuits, including electrical components, conductors and connections between them. And here the condition for the correct designation of the same type of electronic components and products becomes of utmost importance. For this purpose, positional designations are used, a mandatory part of which is the letter designation of the type of element, the type of its design and the digital designation of the ERE number. The diagrams also use additional part designation of the ERE position, indicating the function of the element, in the form of a letter. The main types of letter designations for circuit elements are given in Table. 1.1.

Designations on drawings and diagrams of elements general use refer to qualifications that establish the type of current and voltage. type of connection, control methods, pulse shape, type of modulation, electrical connections, direction of current transmission, signal, energy flow, etc.

Currently, the population and the trading network are using a significant number of various electronic instruments and devices, radio and television equipment, which are manufactured by foreign companies and various joint stock companies. You can buy it in stores Various types ERI and ERE with foreign designations. In table 1. 2 provides information about the most common EREs foreign countries with appropriate designations and their domestically produced analogues.

This is the first time this information has been published in such a volume.

1- pnp structure transistor in a housing, general designation;

2- transistor n-p-n structures in the body, general designation,

3 - field effect transistor with p-n junction and n channel,

4 - field-effect transistor with p-n junction and p channel,

5 - unijunction transistor with n-type base, b1, b2 - base terminals, e - emitter terminal,

6 - photodiode,

7 - rectifier diode,

8 - zener diode (avalanche rectifier diode) one-sided,

9 - thermal-electric diode,

10 - diode dinistor, lockable in the opposite direction;

11 - zener diode (diodolavin rectifier) ​​with bidirectional conductivity,

12 - triode thyristor;

13 - photoresistor;

14 - variable resistor, rheostat, general designation,

15 - variable resistor,

16 - variable resistor with taps,

17 - trimming resistor-potentiometer;

18 - positive temperature coefficient thermistor direct heating(heating),

19 - varistor;

20 - constant capacitor, general designation;

21 - polarized constant capacitor;

22 - oxide polarized electrolytic capacitor, general designation;

23 - constant resistor, general designation;

24 - constant resistor with a rated power of 0.05 W;

25 - constant resistor with a rated power of 0.125 W,

26 - constant resistor with a rated power of 0.25 W,

27 - constant resistor with a rated power of 0.5 W,

28 - constant resistor with a rated power of 1 W,

29 - constant resistor with a rated dissipation power of 2 W,

30 - constant resistor with a rated dissipation power of 5 W;

31 - constant resistor with one symmetrical additional tap;

32 - constant resistor with one asymmetrical additional tap;

Fig 1.1 Symbols of graphical symbols of electrical power in electrical, radio and automation circuits

33 - non-polarized oxide capacitor;

34 - feed-through capacitor (the arc indicates the housing, the external electrode);

35 - variable capacitor (arrow indicates rotor);

36 - trimming capacitor, general designation;

37 - varicond;

38 - noise suppression capacitor;

39 - LED;

40 - tunnel diode;

41 - incandescent lighting and signal lamp;

42 - electric bell;

43 - galvanic or battery element;

44 - electrical communication line with one branch;

45 - electrical communication line with two branches;

46 - a group of wires connected to one point electrical connection. Two wires;

47 - four wires connected to one electrical connection point;

48 - battery made of galvanic cells or rechargeable battery;

49 - coaxial cable. The screen is connected to the body;

50 - winding of a transformer, autotransformer, choke, magnetic amplifier;

51 - working winding of the magnetic amplifier;

52 - control winding of the magnetic amplifier;

53 - transformer without a core (magnetic core) with permanent connection (the dots indicate the beginning of the windings);

54 - transformer with a magnetodielectric core;

55 - inductor, choke without magnetic circuit;

56 - single-phase transformer with a ferromagnetic magnetic core and a screen between the windings;

57 - single-phase three-winding transformer with a ferromagnetic magnetic core with a tap in the secondary winding;

58 - single-phase autotransformer with voltage regulation;

59 - fuse;

60 - fuse switch;

61 - fuse-disconnector;

62 - detachable contact connection;

63 - amplifier (the direction of signal transmission is indicated by the top of the triangle on the horizontal communication line);

64 - pin of detachable contact connection;

Fig 1.1 Symbols of graphical symbols of electronic electrical power in electrical, radio and automation circuits

65 - detachable contact connection socket,

66 - contact collapsible connection for example using a clamp

67 - contact of a permanent connection, for example, made by soldering

68 - single-pole push-button switch with self-resetting closing contact

69 - breaking contact of the switching device, general designation

70 - closing contact of the switching device (switch, relay), general designation. Single pole switch.

71 - switching device contact, general designation. Single pole double throw switch.

72- three-position switching contact with neutral position

73 - normally open contact without self-return

74 - push-button switch with normally open contact

75 - push-button pull-out switch with normally open contact

76 - push-button switch with button return,

77 - push-button pull-out switch with normally open contact

78 - push-button switch with return by pressing the button a second time,

79 - electric relay with normally open and switching contacts,

80 - relay polarized for one direction of current in a winding with a neutral position

81 - relay polarized for both directions of current in a winding with a neutral position

82 - electrothermal relay without self-reset, with return by pressing the button again,

83 - detachable single-pole connection

84 - socket of five-wire contact connector

85 - pin of contact detachable coaxial connection

86 - contact connection socket

87 - four-wire connection pin

88 - four-wire connection socket

89 - jumper switching breaking circuit

Table 1.1. Letter designations circuit elements

Continuation of Table 1.1