Symbol of the button on the diagram. Diode markings and designation diagram. Unified system of design documentation

Almost all electronic equipment, 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. 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 an additional part of the ERE position designation, 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.

Designations in drawings and diagrams of elements of general use refer to qualification ones, establishing 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. In stores you can purchase various types of ERI and ERI with foreign designations. In table 1. 2 provides information about the most common EREs of foreign countries with the corresponding designations and their domestically produced analogues.

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

1- transistor of p-n-p structure in a housing, general designation;

2- transistor of p-p-p structure in the housing, 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 thyristor, erasable in the opposite direction;

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

12 - triode thyristor.

13 - photoresistor,

14 - variable resistor, rheostat, general designation,

15 - variable resistor,

16 - variable resistor with taps,

17 - construction resistor-potentiometer;

18 - thermistor with positive temperature coefficient of 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;

Conventional graphic symbols of electronic electrical power in electrical, radio engineering and automation diagrams

33 - non-polarized oxide capacitor,

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

35 - variable capacitor (arrow indicates rotor);

36 - trimming capacitor, general designation

37 - varicap.

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 electrical connection point. 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;

b1 - 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 - detachable contact connection pin;

Conventional graphic symbols of electronic electrical power in electrical, radio engineering and automation diagrams

65 - socket for detachable contact connection,

66 - contact for removable connection, for example using a clamp

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

68 - single-pole push-button switch with NO contact
self-return

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-plug single-pole connection

84 - socket of a five-wire contact plug connection,

85 pin removable coaxial connection

86 - contact connection socket

87 - four-wire connection pin,

88 four-wire connection socket

89 - jumper switching breaking circuit

Symbols of circuit elements

Standard conventional graphic and letter designations for elements of electrical circuits

Website materials used.

- the simplest semiconductor devices, the basis of which is the electron-hole transition ( pn junction). As is known, the main property of a p-n junction is one-way conductivity: from region p (anode) to region n (cathode). This is also clearly conveyed by the conventional graphic symbol of a semiconductor diode: a triangle (symbol of the anode), together with the electrical connection line crossing it, forms something like an arrow indicating the direction of conduction. The dash perpendicular to this arrow symbolizes the cathode ( rice. 7.1).

The letter code of the diodes is VD. This code denotes not only individual diodes, but also entire groups, for example, rectifying poles. The exception is a single-phase rectifier bridge, depicted as a square with the corresponding number of terminals and a diode symbol inside ( rice. 7.2, VD1). The polarity of the voltage rectified by the bridge is not indicated on the diagrams, since it is clearly determined by the diode symbol. Single-phase bridges, structurally combined in one housing, are depicted separately, indicating that they belong to one product in the position designation (see. rice. 7.2, VD2.1, VD2.2). Next to the position designation of the diode, you can also indicate its type.

On the basis of the basic symbol, graphic symbols for semiconductor diodes with special properties are also constructed. To show on the diagram zener diode, the cathode is supplemented with a short stroke directed towards the anode symbol ( rice. 7.3, VD1). It should be noted that the location of the stroke relative to the anode symbol should be unchanged regardless of the position of the zener diode UGO in the diagram (VD2-VD4). This also applies to the symbol of a two-anode (double-sided) zener diode (VD5).

Conventional graphic symbols are constructed in a similar way tunnel diodes, reversed and Schottky diodes— semiconductor devices used for signal processing in the microwave region. In the tunnel diode symbol (see Fig. 7.3 , VD8) the cathode is supplemented with two strokes directed in one direction (towards the anode), in the UGO of the Schottky diode (VD10) - in different directions; in the UGO of the reversed diode (VD9) - both lines touch the cathode with their middle.

The property of a reverse-biased p-n junction to behave like an electrical capacitance is used in special diodes - varicapah(from words vari(able)- variable and cap(acitor)- capacitor). The conventional graphic designation of these devices clearly reflects their purpose ( rice. 7.3, VD6): two parallel lines are perceived as a capacitor symbol. Like variable capacitors, for convenience, varicaps are often manufactured in the form of blocks (they are called matrices) with a common cathode and separate anodes. For example in Fig. Figure 7.3 shows the UGO of a matrix of two varicaps (VD7).

The basic diode symbol is also used in the UGO thyristors(from Greek Thyra- door and English resistor- resistor) - semiconductor devices with three r-l junctions (p-n-p-n structure), used as switching diodes. The letter code of these devices is VS.

Thyristors with leads only from the outermost layers of the structure are called dinistors and is designated by a diode symbol, crossed out by a line segment parallel to the cathode ( rice. 7.4, VS1). The same technique was used when constructing the UGO symmetrical dinistor(VS2), conducting current (after it is turned on) in both directions. Thyristors with an additional, third output (from one of the internal layers of the structure) are called thyristors. Control along the cathode in the UGO of these devices is shown by a broken line attached to the cathode symbol (VS3), along the anode - by a line extending one of the sides of the triangle symbolizing the anode (VS4). The graphic designation of a symmetrical (bidirectional) thyristor is obtained from the symbol of a symmetrical dinistor by adding third output (see Fig.7.4, VS5).

Of the diodes that change their parameters under the influence of external factors, the most widely used photodiodes. To show such a semiconductor device in a diagram, the basic symbol of a diode is placed in a circle, and next to it (top left, regardless of the position of the UGO) a sign of the photoelectric effect is placed - two oblique parallel arrows directed towards the symbol ( rice. 7.5, VD1—VD3). The UGO of any other semiconductor diode controlled by optical radiation is constructed in a similar way. On rice. 7.5 As an example, the conventional graphic designation of photodinistor VD4 is shown.

Conventional graphic symbols are constructed in a similar way light emitting diodes, but arrows indicating optical radiation are placed at the top right, regardless of the position of the UGO and are directed in the opposite direction ( rice. 7.6). Since LEDs emitting visible light are usually used as indicators, they are designated in diagrams by the Latin letters HL. The standard letter code D is used only for infrared (IR) LEDs.
LED character indicators are often used to display numbers, letters and other characters. Conventional graphic symbols for such devices are not formally provided for in GOST, but in practice symbols like HL3, shown in rice. 7.6, which shows the UGO of a seven-segment indicator for displaying numbers and a comma. Segments of such indicators are designated by lowercase letters of the Latin alphabet in a clockwise direction, starting from the top. This symbol clearly reflects the almost real arrangement of light-emitting elements (segments) in the indicator, although it is not without a drawback; it does not carry information about the polarity of inclusion in the electrical circuit (since similar indicators are produced with both a common anode and a common cathode, the connection patterns will differ). However, this does not cause any particular difficulties, since the connection of the common terminal of the indicators is usually indicated on the diagram. The letter code of the sign indicators is HG.

Light-emitting crystals are widely used in optocouplers - special devices used to connect individual parts of electronic devices in cases where their galvanic isolation is necessary. In the diagrams, optocouplers are designated by the letter U and depicted as shown in rice. 7.7.

The optical connection between the emitter (LED) and the photodetector is shown in this case by two arrows perpendicular to the electrical communication lines - the outputs of the optocoupler. The photodetector in the optocoupler can be a photodiode (see. rice. 7.7, U1), photothyristor U2, photoresistor U3, etc. The relative orientation of the symbols of the emitter and photodetector is not regulated. If necessary, the components of the optocoupler can be depicted separately, but in this case the optical connection sign should be replaced with the signs of optical radiation and photoelectric effect, and the belonging of the parts to one product should be shown in the position designation (see. rice. 7.7, U4.1, U4.2).

Diodes are the simplest semiconductor devices, the basis of which is an electron-hole junction (p-n junction). As is known, the main property of a p-n junction is one-way conductivity: from region p (anode) to region n (cathode). This is clearly conveyed by the conventional graphic designation of a semiconductor diode: a triangle (symbol of the anode), together with the electrical connection line crossing it, forms something like an arrow indicating the direction of conduction. The line perpendicular to this arrow symbolizes the cathode (Fig. 1).

Fig.1. Symbol for diodes

The letter code of the diodes is VD. This code designates not only individual diodes, but also entire groups, for example, rectifier columns (see Fig. 1, VD4). The exception is a single-phase rectifier bridge, depicted as a square with the corresponding number of terminals and a diode symbol inside (Fig. 2, VD1). The polarity of the rectified voltage bridge is not indicated on the diagrams, since it is clearly determined by the diode symbol. Single-phase bridges, structurally combined in one housing, are depicted separately, indicating that they belong to one product in the position designation (see Fig. 2, VD2.1, VD2.2). Next to the position designation of the diode, you can also indicate its type.

Fig.2. Symbol for diode bridges

On the basis of the basic symbol, graphic symbols for semiconductor diodes with special properties are also constructed. To show a zener diode in the diagram, the cathode is supplemented with a short stroke directed towards the anode symbol (Fig. 3, VD1). It should be noted that the location of the stroke relative to the anode symbol should be unchanged regardless of the position of the zener diode symbol on the diagram (VD2-VD4). This also applies to the symbol of a two-anode (double-sided) zener diode (VD5).

Fig.3. Symbol for zener diodes, varicaps, Schottky diodes

The graphical symbols for tunnel diodes, inverted diodes and Schottky diodes - semiconductor devices used for signal processing in the microwave region - are constructed in a similar way. In the symbol of a tunnel diode (see Fig. 3, VD8), the cathode is supplemented with two strokes directed in one direction (towards the anode), in the designation of a Schottky diode (VD10) - in different directions; in the designation of a reversed diode (VD9) - both strokes touch the cathode with their middle.

The property of a reverse biased p-n junction to behave like an electrical capacitance is used in special diodes - varicapah(from the words vari(able) - variable and cap(acitor) - capacitor). The conventional graphic designation of these devices clearly reflects their purpose (Fig. 3, VD6): two parallel lines are perceived as a symbol of a capacitor. Like variable capacitors, for convenience, varicaps are often manufactured in the form of blocks (they are called matrices) with a common cathode and separate anodes. For example in Fig. Figure 3 shows the designation of a matrix of two varicaps (VD1).

The basic diode symbol is also used in the designation thyristors(from the Greek thyra - door and English resistor - resistor) - semiconductor devices with three p-n junctions (p-n-p-n structure), used as switching diodes. The letter code of these devices is VS.

Thyristors with leads only from the outermost layers of the structure are called dinistors and is designated by a diode symbol, crossed out by a line segment parallel to the cathode (Fig. 4, VS1). The same technique was used in constructing the designation of a symmetrical dinistor (VS2), which conducts current (after it is turned on) in both directions. Thyristors with an additional, third output (from one of the internal layers of the structure) are called thyristors. The cathode control in the designation of these devices is shown by a broken line attached to the cathode symbol (VS3), and the anode control by a line extending one of the sides of the triangle symbolizing the anode (VS4). The conventional graphic designation of a symmetrical (bidirectional) SCR is obtained from the symbol of a symmetrical dinistor by adding a third pin (see Fig. 4, VS5).

Fig.4. Symbol for dinistors, trinistors

Of the diodes that change their parameters under the influence of external factors, photodiodes are the most widely used. To show such a semiconductor device in a diagram, the basic diode symbol is placed in a circle, and next to it (upper left, regardless of position) the photoelectric effect sign is placed - two oblique parallel arrows directed towards the symbol (Fig. 5, VD1-VD3) . The designations for any other semiconductor diode controlled by optical radiation are constructed in a similar way. In Fig. Figure 5 shows, as an example, the conventional graphic designation of photodinistor VD4.

Fig.5. Symbol for photodiodes

Conventional graphic symbols for light-emitting diodes are constructed similarly, but arrows indicating optical radiation are placed at the top right, regardless of position, and directed in the opposite direction (Fig. 6). Since LEDs emitting visible light are usually used as indicators, they are designated in diagrams by the Latin letters HL. The standard letter code D is used only for infrared (IR) LEDs.

Fig.6. Symbol for LEDs and LED indicators

LED character indicators are often used to display numbers, letters and other characters. Conventional graphic symbols for such devices are not formally provided for in GOST, but in practice symbols similar to HL3, shown in Fig. 6, which shows the designation of a seven-segment indicator for displaying numbers and a comma. Segments of such indicators are designated by lowercase letters of the Latin alphabet in a clockwise direction, starting from the top. This symbol clearly reflects the almost real arrangement of light-emitting elements (segments) in the indicator, although it is not without a drawback; it does not carry information about the polarity of inclusion in the electrical circuit (since similar indicators are produced with both a common anode and a common cathode, the connection patterns will differ). However, this does not cause any particular difficulties, since the connection of the common terminal of the indicators is usually indicated on the diagram. The letter code of the sign indicators is HG.

Light-emitting crystals are widely used in optocouplers- special devices used to connect individual parts of electronic devices in cases where their galvanic isolation is necessary. In the diagrams, optocouplers are designated by the letter U and depicted as shown in Fig. 7.

Fig.7. Symbol for optocouplers

The optical connection of the emitter (LED) and the photodetector is shown in this case by two arrows perpendicular to the electrical communication lines - the outputs of the optocoupler. The photodetector in the optocoupler can be a photodiode (see Fig. 7, U1), photothyristor U2, photoresistor U3, etc. The relative orientation of the symbols of the emitter and photodetector is not regulated. If necessary, the components of the optocoupler can be depicted separately, but in this case, the optical connection sign should be replaced with the signs of optical radiation and photoelectric effect, and the belonging of the parts to one product should be shown in the position designation (see Fig. 7, U4.1, U4.2).

GOST 2.730-73

Group T52

INTERSTATE STANDARD

Unified system of design documentation

CONVENTIONAL GRAPHIC SYMBOLS IN DIAGRAMS

Semiconductor devices

Unified system for design documentation. Graphical symbols in diagrams. Semiconductor devices

ISS 01.080.40
31.080

Date of introduction 1974-07-01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the State Committee of Standards of the Council of Ministers of the USSR

2. APPROVED AND ENTERED INTO EFFECT by Resolution of the State Committee of Standards of the Council of Ministers of the USSR dated 08.16.73 N 2002

3. Complies with ST SEV 661-88

4. INSTEAD OF GOST 2.730-68, GOST 2.747-68 in terms of clauses 33 and 34 of the table

5. EDITION (April 2010) with Amendments No. 1, 2, 3, 4, approved in July 1980, April 1987, March 1989, July 1991 (IUS 10-80, 7-87 , 6-89, 10-91), Amendment (IUS 3-91)

1. This standard establishes the rules for constructing conventional graphic symbols of semiconductor devices on circuits performed manually or automatically in all industries.

(Changed edition, Amendment No. 3).

2. Designations of elements of semiconductor devices are given in Table 1.

Designations of elements of semiconductor devices

Table 1

(Changed edition, Amendment No. 2, 3).

3, 4. (Excluded, Amendment No. 1).
________________
* Tables 2, 3. (Excluded, Amendment No. 1).

5. Signs characterizing the physical properties of semiconductor devices are given in Table 4.

Signs characterizing the physical properties of semiconductor devices

Table 4

6. Examples of constructing designations for semiconductor diodes are given in Table 5.

Examples of constructing symbols for semiconductor diodes

Table 5

7. Designations of thyristors are given in Table 6.

Thyristor designations

Table 6

Note. It is possible to depict the designation of a thyristor controlled by the anode as a continuation of the corresponding side of the triangle.

8. Examples of constructing transistor designations with P-N- transitions are given in Table 7.

Examples of constructing transistor symbols

Table 7

Note. When executing the schemes it is allowed:

a) designate transistors in a mirror image, for example,

b) depict the body of the transistor.

9. Examples of constructing designations for field-effect transistors are given in Table 8.

Examples of constructing designations for field-effect transistors

Table 8

Note. It is allowed to depict the housing of transistors.

10. Examples of designations for photosensitive and emitting semiconductor devices are given in Table 9.

Examples of construction of designations for photosensitive and emitting semiconductor devices

Table 9

11. Examples of constructing designations for optoelectronic devices are given in Table 10

Examples of constructing designations for optoelectronic devices

Table 10

The ability to read electrical diagrams, the ability to recognize various conventional graphic symbols of switching devices and network elements indicated on a house drawing will allow you to understand the wiring arrangement yourself.

A diagram that is understandable to the user gives him the answer to the question of which wires to connect to which terminals of the electrical appliance. But to read a drawing, it is not enough to remember the symbols of various electrical devices; you also need to understand what they do, what functions they perform in order to grasp the relationship between them, which is necessary in order to understand the operation of the entire system.

A lot of time is devoted to the study of the entire range of electrical devices in special educational institutions, and there is no way in one article to contain the designation of all these devices, with a detailed description of their functionality and characteristic relationships with other devices.

Therefore, you need to start by studying simple circuits that include a small set of elements.

Conductors, lines, cables

The most common component of any electrical network is the wire identification. In the diagrams it is indicated by a line. But you need to remember that one segment in the drawing can mean:

• one wire, which is the electrical connection between the contacts;
• two-wire single-phase or four-wire three-phase group electrical communication line;
• an electrical cable that includes a whole set of power and signal groups of electrical connections.

As we see, already at the stage of studying the seemingly simplest wires, there are complex, varied designations for their varieties and interactions.

This fragment from table No. 6 of GOST 2.721-74 shows various designations of elements, both simple single-core connections and their intersections, and conductor harnesses with branches.

There's no point in starting to memorize all these icons. They themselves will be deposited in the mind after studying various drawings, in which from time to time you will have to look at this table.

Network components

A set of elements consisting of a lamp, switch, socket is sufficient for the functioning of a living room; it provides lighting and power to electrical appliances.

Having learned their designations, you can easily understand the wiring in your room, or even design your own wiring plan that takes into account your immediate needs.

Looking at table No. 1 of GOST 21.608-84, one may be surprised at the variety of electrical products available in everyday use. While at home and reading this article, you should look around and find electrical components in your room that correspond to those indicated in the table. For example, a socket is indicated on the diagram by a semicircle.

There are many varieties of them (only phase and neutral, with an additional grounding contact, double, block with switches, hidden, etc.), so each has its own graphic designation, as well as many types of switches.

A little practice for memorization

Having highlighted the found elements, it is advisable to try to draw them, you can even follow the rules indicated in table No. 2. This exercise will help you remember the selected components.

Having the outline of graphic symbols, you can connect them with lines and get a wiring diagram in the room. Since the wires are hidden in the wall covering, it will not be possible to draw an installation drawing, but the electrical diagram will be correct.

The slashes indicate the number of conductors in the line. The arrows indicate the exits to the panel with circuit breakers and RCDs. The blue line means a connection with a two-wire cable to the distribution box, from which three wires go to the switch and the lamp.

Three-wire wiring with a PE protective conductor is shown in black. This figure is provided as an example only. To design complex electrical systems, you need to take a whole course at a higher specialized educational institution.

But, having learned a few common symbols, you can draw the wiring of a room, a garage or an entire house by hand, and work on it, turning it into reality.

RCD, automatic devices, electrical panel

To complete the picture, you also need to find out the designation of distribution boxes, circuit breakers, RCDs, and meters.

The image shows that a single-pole circuit breaker differs from a two-pole circuit breaker by the presence of oblique lines on the designation of the connection wires.

Protective systems

To be able to understand the arrangement of the entire wiring of a country house (not just the electrical network), you also need to study the means of lightning protection, zero, phase, motion sensor icon and other POS (fire and security alarm) signaling devices.

The figure shows a diagram of lightning protection of a country house with a wire lightning rod installed on the roof:

1. wire lightning rod;
2. input of overhead overhead lines and grounding of overhead line hooks on the wall;
3. current lead;
4. ground loop.

Alarm sensors have their own specific designation; in the data sheets of some manufacturers they may differ. The most typical symbols represent the PIC tools described below.

This figure shows a plan of a cottage with a diagram of the connection of various fire and security alarm sensors.

This article shows that part of the designation that concerns the arrangement of a house or apartment. To become more fully familiar with the graphic symbols of electrical engineering and other industries, you need to study GOST and various reference books.

And once again it is worth recalling that it is not enough to learn the icons, you need to understand the principle of operation of the designated elements in electrics.