Decoding of electrical designations of letters. Conventional designation in electrical circuits. Conditional graphic and letter symbols. Designations of electromechanical devices and contact connections

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

Applied purchased components or self-manufactured ERE are necessarily reflected in the schematic and wiring diagrams of devices, in drawings and other TD, which are carried out in accordance with the requirements of ESKD standards.

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

The connection of the list of ERE components with their conventional graphic designations is carried out through the reference designations.

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

The standardized and most commonly used conventional graphic designations of ERE in electrical circuit diagrams are shown in Fig. 1. 1. These designations relate to all component elements of the circuits, including ERE, conductors and connections between them. And here the condition for the correct designation of the same type of ERE components and products is of paramount importance. For this purpose, reference 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 the 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 of circuit elements are given in table. 1.1.

The designations in the 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 transmission of current, signal, energy flow, etc.

Currently, the population and in trading network a significant number of various electronic devices and devices, radio and television equipment are in operation, which are manufactured by foreign firms and various joint stock companies. In stores, you can buy various types of ERI and ERE with foreign designations. Table 1. 2 provides information about the most common ERE of foreign countries with the appropriate designations and their analogues of domestic production.

This information is published for the first time in such a volume.

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

2- transistor n-p-n structures in the case, 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 base n type, b1, b2 - base terminals, e - emitter output,

6 - photodiode,

7 - rectifying diode,

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

9 - heat-electric diode,

10 - diode dinistor, lockable in the opposite direction;

11 - zener diode (diode avalanche rectifier) \u200b\u200bwith double-sided conductivity,

12 - triode thyristor;

13 - photoresistor;

14 - variable resistor, rheostat, general designation,

15 - variable resistor,

16 - variable resistor with taps,

17 - trimmer potentiometer;

18 - thermistor with a positive temperature coefficient of direct heating (heating),

19 - varistor;

20 - constant capacitor, general designation;

21 - polarized fixed capacitor;

22 - polarized electrolytic oxide 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 power dissipation of 2 W,

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

31 - constant resistor with one symmetrical additional tap;

32 - constant resistor with one asymmetrical additional tap;

Fig 1.1 Symbols of ERE in electrical, radio engineering and automation circuits

33 - non-polarized oxide capacitor;

34 - pass-through capacitor (the arc denotes the case, the external electrode);

35 - variable capacitor (arrow indicates rotor);

36 - trimmer capacitor, general designation;

37 - varicond;

38 - noise suppression capacitor;

39 - LED;

40 - tunnel diode;

41 - lighting and signal incandescent lamp;

42 - electric bell;

43 - galvanic or battery cell;

44 - electrical communication line with one branch;

45 - electrical communication line with two branches;

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

47 - four wires connected to one electrical connection point;

48 - a battery of galvanic cells or a 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 circuit) with permanent coupling (dots indicate the beginning of the windings);

54 - transformer with a magnetodielectric core;

55 - inductor coil, 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 circuit with a tap in the secondary winding;

58 - single-phase autotransformer with voltage regulation;

59 - fuse;

60 - fuse switch;

61 - fuse disconnector;

62 - detachable pin connection;

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

64 - pin of detachable contact connection;

Fig 1.1 Symbols of ERE in electrical radio engineering and automation circuits

65 - socket of detachable contact connection,

66 - contact of a dismountable connection for example using a clip

67 - contact of a non-separable connection, for example carried out by soldering

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

69 - contact of the switching device opening, general designation

70 - closing contact of a switching device (switch, relay), general designation. The switch is single-pole.

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

72- three-position changeover contact with neutral position

73 - closing contact without self-return

74 - push-button switch with break contact

75 - push-button exhaust switch with NO contact

76 - push-button switch with button return,

77 - push-button exhaust switch with a break contact

78 - push-button switch with return by pressing the button again,

79 - electrical relay with normally open and changeover contacts,

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

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

82 - electric thermal relay without self-return, with a return by pressing the button a second time,

83 - detachable single-pole connection

84 - socket of a five-wire pin plug connection

85 - pin of the pin detachable coaxial connection

86 - socket of contact connection

87 - pin four-wire connection

88 - socket of a four-wire connection

89 - jumper switching opening circuit

Table 1.1. Letter designations of circuit elements

Continuation of table 1.1

Sooner or later, when carrying out electrical installation or electrical repair work, you have to deal with electrical circuits that contain many alphanumeric and conventionally graphic symbols. The latter will be discussed in this article. There are a large number of types of electrical circuit elements that have the most different functions, therefore, there is no single document that determines the correctness of the graphic designation of all the elements that can be found on the diagrams. The tables below show some examples of conventional graphic images of electrical equipment and wiring, elements of electrical circuits on diagrams taken from various documents currently in force. You can download the required GOST in its entirety by clicking on the links at the bottom of the page.

Free download GOST

• GOST 21.614Conditional graphic images of electrical equipment and wiring in the original

• GOST 2.722-68 Conditional graphic designations in schemes. Electrical machines

• GOST 2.723-68 Conditional graphic designations in schemes. Inductors, reactors, chokes, transformers, autotransformers and magnetic amplifiers

• GOST 2.729-68 Conditional graphic designations in schemes. Electrical measuring instruments

• GOST 2.755-87 Conditional graphic designations in schemes. Switching devices and contact connections

Alphanumeric designations in electrical circuits (GOST 2.710 - 81)

The letter codes of the elements are shown in the table. Positional designations to elements (devices) are assigned within the product. Serial numbers elements (devices) should be assigned, starting from one, within a group of elements having the same letter code in accordance with the sequence of the elements or devices on the diagram from top to bottom in the direction from left to right.

Positional designations are placed on the diagram next to the conventional graphic designation of elements or devices on the right side or above them. The numbers and letters included in the reference designation are of the same size.

One-book war code	Item View Groups	Examples of element types	Two-book war code
A	Devices (general designation)	-	-
B	Non-electrical to electrical converters (excluding generators and power supplies) or vice versa	Selsin - receiver	BE
		Selsin - sensor	BC
		Thermal sensor	BK
		Photocell	BL
		Pressure meter	BP
		Tachogenerator	BR
		Speed \u200b\u200bsensor	BV
C	Capacitors	-	-
D	Integrated circuits, micro-assemblies	Integrated circuit, analog	DA
		Integrated circuit, digital, logical element	DD
		Delay device	DT
		Information storage device	DS
E	Elements are different	A heating element	EK
		Lighting lamp	EL
F	Arresters, fuses, protective devices	Discrete security element instantaneous current	FA
		Discrete security element inertial current	FP
		Discrete security element stress	FV
		Fuse	FU
G	Generators, power supplies	Battery	GB
H	Indicator and signal elements	Sound alarm device	HA
		Character indicator	HG
		Light signaling device	HL
K	Relays, contactors, starters	Indicator relay	KH
		Relay current	KA
		Electric thermal relay	KK
		Contactor, magnetic starter	KM
		Polarized relay	KP
		Time relay	KT
		Voltage relay	KV
L	Inductors, chokes	Fluorescent light choke	LL
M	Engines	-	-
P	Instruments, measuring equipment	Ammeter	PA
		Pulse counter	PC
		Frequency meter	PF
		Reactive energy meter	PK
		Active energy meter	PI
		Ohmmeter	PR
		Recording device	PS
		Time meter, clock	PT
		Voltmeter	PV
		Wattmeter	PW
Q	Switches and disconnectors in power circuits	Automatic switch	QF
		Disconnector	QS
R	Resistors	Thermistor	RK
		Potentiometer	RP
		Measuring shunt	RS
		Varistor	RU
S	Switching devices in control, signaling and measuring circuits Note... The designation is used for devices without power circuit contacts	Switch or switch	SA
		Push-button switch	SB
		Automatic switch	SF
		Switches triggered by various influences: -from the level	SL
		-from pressure	SP
		-from position	SQ
		-from rotation frequency	SR
		-from temperature	SK
T	Transformers, autotransformers	Current transformer	TA
		Voltage transformer	TV
		Stabilizer	TS
U	Converters of electrical quantities to electrical	Frequency converter, inverter rectifier	UZ
V	Electrovacuum and semiconductor devices	Diode, Zener diode	VD
		Electrovacuum devices	VL
		Transistor	VT
		Thyristor	VS
X	Contact connections	Current collector	XA
		Pin	XP
		Nest	XS
		Collapsible connections	XT
Y	Mechanical devices with electromagnetic drive	Electromagnet	YA
		Electromagnetic brake driven	YB
		Electromagnetic plate	YH

CONDITIONAL GRAPHIC DESIGNATIONS IN SCHEMES. ELECTRIC MACHINES (GOST 2.722-68)

1. Three ways of constructing conventional graphic symbols for electrical machines are established:

1. simplified single line;
2. simplified multi-line (form I);
3. expanded (form II).

2. In simplified single-line designations of electrical machines, the stator and rotor windings are depicted as circles. The terminals of the stator and rotor windings are shown with one line indicating the number of terminals on it in accordance with the requirements of GOST 2.751-73.

3. In the simplified multi-line designations, the stator and rotor windings are depicted similarly to the simplified single-line designations, showing the terminals of the stator and rotor windings (Fig. 1).

4. In expanded designations, the stator windings are depicted as chains of semicircles, and the rotor windings are shown as a circle (and vice versa).

The mutual arrangement of the windings is depicted:

1. a) in AC and universal machines - taking into account (Fig. 2) or not taking into account (Fig. 3) phase displacement;
2. b) in DC machines - taking into account (Fig. 4) or not taking into account (Fig. 5) the direction of the magnetic field created by the winding.

5. In the examples of conventional graphic designations of AC machines and universal machines, designations are given, as a rule, reflecting the phase shift in the winding, in examples of DC machines, as a rule, without taking into account the direction of the magnetic field.

6. The conclusions of the stator and rotor windings in the designations of machines of all types may be depicted from either side.

7. Designations of elements of electrical machines are given in table. 1.

SYMBOLS IN ELECTRICAL CIRCUITS ACCORDING TO GOST 7624-55

In the Soviet Union in 1955, GOST 7624-55 was adopted for a number of designations in radio engineering schemes, canceled in 1964. Considering that the schemes with the old designations are still preserved, below are the basic designations from GOST 7624-55. Legend wires, individual elements machines and apparatus (GOST 7624-55)

SYMBOLS. ELECTRICAL MEASURING DEVICES (GOST 2.729-68)

The table shows some of the conventional graphic designations of electro measuring instruments.

Reading electrical circuits is a necessary skill to represent the operation of electrical networks, nodes, as well as various equipment. Not a single specialist will begin to install the equipment until he or she reads the accompanying regulatory documents.

Schematic electrical diagrams allow the developer to convey a complete report on the product in a compressed form to the user, using conventionally graphic symbols (UGO). To avoid confusion and defects when assembling according to drawings, alphanumeric designations are entered into a unified system for design documentation (ESKD). All schematic diagrams are developed and applied in full accordance with GOSTs (21.614, 2.722-68, 2.763-68, 2.729-68, 2.755-87). The GOST describes the elements, provides a decoding of the values.

Reading drawings

The schematic diagram shows all the elements, parts and networks that make up the drawing, electrical and mechanical connections. Reveals the full functionality of the system. All elements of any electrical circuit correspond to the designations positioned in GOST.

A list of documents is attached to the drawing, in which all the elements and their parameters are prescribed. The components are listed in alphabetical order with numerical sorting. The list of documents (specification) is indicated on the drawing itself, or made out in separate sheets.

How to study drawings

First, the type of drawing is determined. According to GOST 2.702-75, an individual code corresponds to each graphic document. All electrical drawings have the letter designation "E" and the corresponding digital value from 0 to 7. Electrical schematic diagram corresponds to the code "E3".

Reading the circuit diagram:

• Visually get acquainted with the presented drawing, pay attention to the indicated notes and technical requirements.
• Find on the schematic image all the components indicated in the document list;
• Determine the power source of the system and the type of current (single-phase, three-phase);
• Find the main components, and determine their power supply;
• Get acquainted with the elements and protection devices;
• Study the control method indicated on the document, its tasks and the algorithm of actions. Understand the sequence of actions of the device when starting, stopping, short circuit;
• Analyze the work of each section of the chain, determine the main components, auxiliary elements, study the technical documentation of the listed parts;
• Based on the studied data of the document, draw a conclusion about the processes taking place in each link of the chain shown in the drawing.

Knowing the sequence of actions, alphanumeric designations, you can read any electrical diagram.

Graphic symbols

The schematic diagram has two types - single-line and complete. On a single-line, only the power wire with all the elements is drawn, if the main network does not differ in individual additions from the standard one. Two or three slashes applied to the wire line denote a single-phase or three-phase network, respectively. The entire network is drawn in full and the generally accepted symbols in the electrical circuits are put down.

Single line electrical circuit, single phase network

Types and meaning of lines

1. Thin and thick solid lines - in the drawings depicts lines of electrical, group communication, lines on the elements of the UGO.
2. Dashed line - indicates the shielding of the wire or devices; denotes a mechanical link (motor - gear).
3. Thin dash-dotted line - designed to highlight groups of several components that make up parts of the device, or a control system.
4. A dash-dotted line with two dots is a disconnecting line. Shows a breakdown of important items. Indicates an object remote from the device, connected to the system by mechanical or electrical communication.

Network trunks are shown completely, but according to standards, they are allowed to be cut if they interfere with the normal understanding of the circuit. The break is indicated by arrows, next to the main parameters and characteristics of electrical circuits.

The bold point on the lines indicates the connection, the soldering of the wires.

Electromechanical components

Schematic representation of electromechanical links and contacts

A - UGO coil of an electromechanical element (magnetic starter, relay)

B - thermal relay

C - device coil with mechanical interlock

D - closing contacts (1), opening (2), switching (3)

E - button

F - designation of the switch (knife switch) on the electrical diagram of the UGO of some measuring instruments. A complete list of these elements is given in GOST 2.729 68 and 2.730 73.

Elements of electrical circuits, devices

Figure number	Description	Figure number	Description
1	Electricity meter	8	Electrolytic capacitor
2	Ammeter	9	Diode
3	Voltmeter	10	Light-emitting diode
4	temperature sensor	11	Diode optocoupler
5	Resistor	12	Npn transistor picture
6	Rheostat (variable resistor)	13	Fuse
7	Capacitor

UGO time relays, buttons, switches, limit switches are often used in the development of electric drive circuits.

Schematic representation of a fuse. When reading the electrical diagram, you should carefully consider all the lines and parameters of the drawing so as not to confuse the purpose of the element. For example, the fuse and resistor are slightly different. In the diagrams, the power line is shown passing through the fuse, the resistor is drawn without internal elements.

Full diagram of the circuit breaker

Contact switching device. Serves as automatic protection electrical network from accidents, short circuit... Mechanically or electrically powered.

Single-line circuit breaker

The transformer is a steel core with two windings. There is one and three-phase, step-up and step-down. It is also divided into dry and oil, depending on the cooling method. Power ranges from 0.1 MVA to 630 MVA (in Russia).

UGO transformers

Designation of current transformers on the full (a) and single-line (c) diagram

Graphic designation of electrical machines (EM)

Electric motors, depending on the type, are capable of not only consuming energy. When developing industrial systems, motors are used, which, in the absence of a load, generate energy into the network, thereby reducing costs.

A - Three-phase electric motors:

1 - Asynchronous with squirrel-cage rotor

2 - Asynchronous with a squirrel-cage rotor, two-speed

3 - Asynchronous with phase rotor

4 - Synchronous electric motors; generators.

B - DC collector motors:

1 - with excitation of the winding from a permanent magnet

2 - Electric machine with excitation coil

In conjunction with electric motors, the diagrams show magnetic starters, soft starters, and a frequency converter. These devices are used to start electric motors, smooth system operation. The last two elements protect the network from voltage “sag” in the network.

UGO magnetic starter on the diagram

Switches function as switching equipment. Disconnect and turn on certain sections of the network, as needed.

Graphic symbols in electrical diagrams of mechanical switches

Conditional graphic designations of sockets and switches in electrical circuits. Include in the developed drawings of electrification of houses, apartments, industries.

Bell on the electrical diagram according to UGO standards with a designated size

Dimensions of UGO in electrical circuits

On the diagrams, the parameters of the elements included in the drawing are applied. Full information about the element, capacitance, if it is a capacitor, rated voltage, resistance for the resistor are registered. This is done for convenience, so as not to make a mistake during installation, not to waste time on calculating and selecting the components of the device.

Sometimes the nominal data is not indicated, in this case the parameters of the element do not matter, you can select and install a link with a minimum value.

The accepted dimensions of the UGO are prescribed in the GOSTs of the ESKD standard.

Dimensions in ESKD

The dimensions of graphic and letter images in the drawing, the thickness of the lines should not differ, but it is permissible to change them proportionally in the drawing. If in the symbols on various electrical circuits of GOST, there are elements that do not have information about the sizes, then these components are performed in sizes corresponding to the standard image of the UGO of the entire circuit.

UGO elements that make up the main product (device) can be drawn in a smaller size in comparison with other elements.

Along with UGO, for a more accurate definition of the name and purpose of elements, a letter designation is applied to the schemes. This designation is used for references in text documents and for application to the object. Using the letter designation, the name of the element is determined, if this is not clear from the drawing, technical specifications, quantity.

Additionally, one or more numbers are indicated with a letter designation, usually they explain the parameters. An additional letter code indicating the denomination, model, additional data is written in the accompanying documents, or is placed in a table in the drawing.

To learn how to read electrical circuits, it is not necessary to know all the letter symbols by heart, graphic images various elements, it is enough to navigate in the corresponding GOST ESKD. The standard includes 64 GOST documents that disclose the main provisions, rules, requirements and designations.

The main symbols used in the diagrams according to the ESKD standard are shown in Tables 1 and 2.

Table 1

First letter of code (required)	Element view group	Examples of element types
A	Devices	Amplifiers, telecontrol devices, lasers, masers
B		Loudspeakers, microphones, thermoelectric sensing elements, ionizing radiation detectors, pickups, selsyns
C	Capacitors
D		Integrated analog digital circuits, logic elements, memory devices, delay devices
E	Elements are different	Lighting devices, heating devices
F		Discrete current and voltage protection elements, fuses, arresters
G	Generators, power supplies, quartz oscillators	Batteries, accumulators, electrochemical and electrothermal sources
H	Indicating and signaling devices	Sound and light alarm devices, indicators
K	Relays, contactors, starters	Current and voltage relays, electric thermal relays, time relays, contactors, magnetic starters
L		Fluorescent light chokes
M	Engines	DC and AC motors
P		Indicating, recording and measuring devices, counters, clocks
Q		Disconnectors, short-circuits, circuit breakers (power)
R	Resistors	Variable resistors, potentiometers, varistors, thermistors
S	Switching devices in control, signaling and measuring circuits	Switches, switches, switches, triggered by various influences
T		Current and voltage transformers, stabilizers
U	Converters of electrical quantities to electrical, communication devices	Modulators, demodulators, discriminators, inverters, frequency converters, rectifiers
V		Electronic tubes, diodes, transistors, thyristors, zener diodes
W	Microwave lines and elements, antennas	Waveguides, dipoles, antennas
X	Contact connections	Pins, sockets, dismountable joints, collectors
Y		Electromagnetic clutches, brakes, chucks
Z	Terminal devices, filters, limiters	Modeling lines, quartz filters

The main two-letter designations are shown in Table 2

First letter of code (required)	Element view group	Examples of element types	Two-letter code
A	Device (general designation)
B	Converters of non-electrical quantities to electrical quantities (other than generators and power supplies) or vice versa analog or multi-digit converters or sensors for indicating or measuring	Speaker	BA
		Magnetostrictive element	BB
		Ionizing element detector	BD
		Selsin - receiver	BE
		Telephone (capsule)	Bf
		Selsin - sensor	BC
		Thermal sensor	BK
		Photocell	BL
		Microphone	BM
		Pressure meter	BP
		Piezoelectric element	BQ
		Speed \u200b\u200bsensor (tachogenerator)	BR
		Pickup	BS
		Speed \u200b\u200bsensor	BV
C	Capacitors
D	Integrated circuits, microassemblies	Analog integrated circuit	DA
		Integrated circuit, digital, logic element	DD
		Information storage device	DS
		Delay device	DT
E	Elements are different	A heating element	EK
		Lighting lamp	EL
		Igniter	ET
F	Arresters, fuses, protective devices	Discrete instantaneous current protection element	FA
		Discrete inertial current protection element	FP
		Fuse fuse	FU
		Discrete voltage protection element, arrester	FV
G	Generators, power supplies	Battery	GB
H	Indicator and signal elements	Sound alarm device	HA
		Character indicator	HG
		Light signaling device	HL
K	Relays, contactors, starters	Relay current	KA
		Indicator relay	KH
		Electric thermal relay	KK
		Contactor, magnetic starter	KM
		Time relay	KT
		Voltage relay	KV
L	Inductors, chokes	Fluorescent light choke	LL
M	Engines	-	-
P	Instruments, measuring equipment	Ammeter	PA
		Pulse counter	PC
		Frequency meter	PF
	Note. The combination of PE is not allowed	Active energy meter	PI
		Reactive energy meter	PK
		Ohmmeter	PR
		Recording device	PS
		Clock, action time meter	PT
		Voltmeter	PV
		Wattmeter	PW
Q	Switches and disconnectors in power circuits	Automatic switch	QF
		Short-circuiter	QK
		Disconnector	QS
R	Resistors	Thermistor	RK
		Potentiometer	RP
		Measuring shunt	RS
		Varistor	RU
S	Switching devices in control, signaling and measuring circuits. Note. The SF designation is used for devices without power circuit contacts.	Switch or switch	SA
		Push-button switch	SB
		Automatic switch	SF
		Switches triggered by various influences: - from level	SL
		- from pressure	SP
		- from position (track)	SQ
		- from the speed	SR
		- from temperature	SK
T	Transformers, autotransformers	Current transformer	TA
		Electromagnetic stabilizer	TS
		Voltage transformer	TV
U	Communication devices. Converters of electrical quantities to electrical	Modulator	UB
		Demodulator	UR
		Discriminator	UI
		Frequency converter, inverter, frequency generator, rectifier	UZ
V	Electrovacuum and semiconductor devices	Diode, Zener diode	VD
		Electrovacuum device	VL
		Transistor	VT
		Thyristor	VS
W	Microwave lines and elements Antennas	Coupler	WE
		Short-circuiter	Wk
		Valve	WS
		Transformer, discontinuity, phase shifter	WT
		Attenuator	WU
		Antenna	WA
X	Contact connections	Current collector, sliding contact	XA
		Pin	XP
		Nest	XS
		Collapsible connection	XT
		High frequency connector	XW
Y	Mechanical devices with electromagnetic drive	Electromagnet	YA
		Electromagnetic brake	YB
		Electromagnetic clutch	YC
		Electromagnetic chuck or plate	YH
Z	Terminal devices Filters. Limiters	Limiter	ZL
		Quartz filter	ZQ

Related Videos

If you are engaged in electrical work, then you definitely need to know the symbols in electrical circuits. The ability to read electrical circuits is an important quality of fitters, instrumentation fitters, circuit designers. And if you do not have special training, you will hardly be able to immediately understand all the intricacies. But it must be remembered that the symbols on the diagrams that are developed for Russian consumers differ from the generally accepted standards abroad - in Europe, the USA, and Japan.

History of schematic symbols

Back in the Soviet years, when electrical engineering was developing rapidly, the need arose for the classification of devices and their designation. It was then that one system design documentation (ESKD) and state standards (GOST). Everything was standardized so that any engineer could read the legend on the drawings of his colleagues.

But in order to make out all the subtleties, you will need to listen to many lectures and study a lot of special literature. GOST is a huge document, and fully study all graphic symbols and their standard sizes, notes are almost impossible. Therefore, you must always have a small "cheat sheet" at hand that will help you navigate in all the variety of electrical components.

Wiring in drawings

Wiring is a generic term and refers to conductors that have very low resistance. With their help, voltage is transmitted from the source of electricity to consumers. This is a general concept as there are many types of electrical wiring.

People who do not understand the diagrams and features of wiring may decide that the conductor is an insulated cable that connects to switches and sockets. But in fact, there are many types of conductors, and they are indicated in different ways in the diagrams.

Schematic conductors

Even copper tracks on PCBs are a conductor, one might even say that this is a variant of electrical wiring. It is indicated on electrical diagrams in the form of a straight connecting line passing from one element to another. In the same way, the electrical wires of the high-voltage line laid in the fields between the poles are indicated on the diagram. And in apartments, connecting wires between lamps, switches and sockets are also indicated by straight connecting lines.

But it can be divided into three subgroups of the designation of conductive elements:

1. Wires.
2. Cables.
3. Electrical connections.

The wiring plan is an incorrect definition, since wiring means both installation wires and cables. But if you significantly expand the list of elements, as is necessary in the detailed diagram, it turns out that it is necessary to include more transformers, circuit breakers, residual current devices, grounding, insulators.

Sockets on the diagrams

Sockets are plug connections designed for non-rigid connection (there is a possibility to manually disconnect the connection) of electrical circuits. Symbols in the drawings are strictly regulated by GOST. With its help, rules have been established for designating devices and lighting devices and various other electrical consumers on the drawings. Plug-in sockets can be divided into three categories:

1. Designed for surface mounting.
2. Designed for hidden installation.
3. A block that includes an outlet and a switch.

1. Single pole sockets.
2. Bipolar.
3. Double pole and protective contact.
4. Three-pole.
5. Three-pole and protective contact.

That's enough, the sockets have no peculiarities, there are many options. All devices have a degree of protection, the choice must be made based on the conditions in which they will be used: humidity level, temperature, presence of mechanical influences.

Switches on wiring diagrams

Switches are devices that break an electrical circuit. This can be done automatically or manual mode... The conditional graphic designation is regulated by GOST, as well as for outlets. The designation depends on the conditions in which the element works, what design it has, the degree of protection. There are several types of switch designs:

1. Single-pole (including double and triple).
2. Bipolar.
3. Three-pole.

The diagrams must indicate the parameters of the disconnecting device. And the graphic designation shows which type is used: a simple one with or without fixation, an acoustic device (responding to cotton) or an optical one. If there is a condition for the lighting to turn on at nightfall and turn off in the morning, an optical sensor and a small control circuit can be used.

Fuses (fuses)

There are many types of protection devices - fuses (disposable and self-restoring), Many types of design, areas of application, different speed of operation, reliability, use in certain conditions characterizes these devices. The symbol of the fuse is a rectangle, parallel to the long side through the center is the simplest and cheapest element that can protect the electrical circuit from short circuits. It should be noted that such components are rarely used in electrical circuit diagrams. Symbols of another type can be found - these are self-healing fuses, which, after opening the circuit, return to their original state.

The broad name of fuses is a fuse link. It is used in many devices, in electrical distribution boards. You can find them in disposable plugs. But there are also devices used in high-voltage. They are structurally made of metal lugs and the main ceramic part. Inside there is a piece of conductor (its cross-section is chosen depending on what maximum current must pass through the circuit). The ceramic body is filled with sand to exclude the possibility of ignition.

Circuit breakers

Symbols of devices of this type depend on the design, the degree of protection. The reusable device can be used as a simple switch. In fact, it performs the functions of a fusible link, but it is possible to transfer it to its original state - to close the circuit. The structure consists of the following elements:

1. Plastic case.
2. Lever for turning on and off.
3. Bimetallic plate - when heated, it deforms.
4. Contact group - it is included in the electrical circuit.
5. Arc chute - allows you to get rid of the formation of sparks and arcs when the connection is broken.

These are the elements that make up any circuit breaker. But you need to remember that after triggering, it will not be able to return immediately to its original position, it must take time for it to cool down. The service life of the machines is measured in the number of operations and ranges from 30,000 to 60,000.

Grounding on diagrams

Grounding is the connection of the current conductors of an electric machine or device to the ground. In this case, both the ground and part of the circuit of the device have a negative potential. Due to grounding, upon breakdown of the case, no destruction of the device or electric shock will follow, all the charge will go into the ground. Grounding is of the following types according to GOST:

1. The general concept of grounding.
2. Clean grounding (noiseless).
3. Protective grounding type.
4. Ground connection (body) of the device.

Depending on what kind of grounding is used in the circuit, the symbol will be different. An important role in drawing up diagrams is played by the drawing of an element, it depends both on a specific section of the circuit and on the type of device.

If a it comes about automotive technology, then there will be "mass" - a common conductor connected to the body. In the case of house wiring, conductors driven into the ground are connected to sockets. IN logic circuits “digital” grounding and normal grounding should not be confused - these are different things and they work in different ways.

Electric motors

On the diagrams of electrical equipment of cars, workshops, devices, you can often find electric motors. Moreover, in industry more than 95% of all motors used are asynchronous with a squirrel-cage rotor. They are designated in the form of a circle, to which three wires (phases) fit. Such electric machines are used in conjunction with and buttons ("Start", "Stop", "Reverse" if necessary).

DC motors are used in automotive engineering, control systems. They have two windings - working and excitation. Instead of the latter, permanent magnets are used on some types of motors. A magnetic field is created with the excitation winding. It pushes the rotor of the motor, which has a counter-directional field - it is created by the winding.

Color coding of wires

In the case of a single-phase power supply, the conductor with a phase is black, gray, purple, pink, red, orange, turquoise, white. Most often you can find brown. This marking is generally accepted and is used in drawing up diagrams, installation. is marked:

1. In blue - zero working (N).
2. Yellow with a green stripe - grounding, protection (PE) wire.
3. Yellow with green and blue marks on the edges - protective and neutral conductors are combined.

It should be noted that the blue marks must be applied during installation. The symbol in electrical diagrams should also have a reference to the presence of labels. The conductor must be marked with the PEN index.

By functional purpose, all conductors are divided as follows:

1. Black wires - for power circuit switching.
2. Red wires - for connections of control, measurement, signaling elements.
3. Blue conductors - control, measurement and signaling in DC operation.
4. Blue marking is made of zero working conductors.
5. Yellow and green are the wires for grounding and protection.

Alphanumeric symbols on the diagrams

The terminals are designated in the electrical circuits as follows:

• U, V, W - wiring phases;
• N - neutral conductor;
• E - grounding;
• PE - protective circuit wire;
• TE - conductor for noiseless connection;
• MM - conductor connected to the body (mass);
• CC is an equipotential conductor.

Designation on wire diagrams:

• L - letter designation (general) of any phase;
• L1, L2, L3 - 1st, 2nd and 3rd phases, respectively;
• N - neutral wire.

In DC circuits:

• L + and L- - positive and negative poles;
• M is the middle conductor.

These are the designations most often used in diagrams and drawings. They can be found in descriptions of simple devices. If you need to read the diagram of a complex device, you will need a lot of knowledge. After all, there are still active elements, passive ones, logic devices, semiconductor components and many others. And each has its own designation on the diagrams.

UGO winding elements

There are many devices that convert electrical current. These are inductors. The transformer symbol in the diagrams is two coils (shown in the form of three semicircles) and a core (in the form of a straight line, usually). The straight line indicates the transformer steel core. But there may be transformer designs that do not have a core, in which case there is nothing on the circuit between the coils. Such a conventional designation of elements can be found in the circuits of radio receiving equipment, for example.

In recent years, technology has increasingly used transformer steel for the manufacture of transformers. It is very heavy, it is difficult to get the plates into the core, there is a buzz when loosening. The use of ferromagnetic cores turns out to be much more effective. They are solid, have the same permeability in all areas. But they have one drawback - the complexity of the repair, since it turns out to be problematic to disassemble and assemble. The designation of a transformer with such a core is practically no different from that in which steel is used.

Conclusion

These are far from all the symbols for electrical circuits, the dimensions of the components are also regulated by GOST. Even simple arrows, connection points have requirements, their drawing is carried out strictly according to the rules. It is necessary to pay attention to one feature - the differences in the schemes made according to domestic and imported standards. The intersection of conductors in foreign circuits is indicated by a semicircle. And there is also such a thing as a sketch - this is an image of something without observing the requirements of GOST for the elements. Separate requirements apply to the sketch itself. Such images can be performed to visually represent the future design, electrical wiring. Subsequently, a drawing is drawn up on it, in which even the designations of conventional cables and connections comply with standards.

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

Regulations

Given the large number of electrical elements, for their alphanumeric (hereinafter BO) and conventionally graphic symbols (UGO), a number of regulatory documents have been developed to exclude discrepancy. Below is a table showing the main standards.

Table 1. Standards for the graphic designation of individual elements in installation and circuit diagrams.

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

It should be borne in mind that the element base changes over time, accordingly, changes are made to the regulatory documents, although this process is more inert. Let's give a simple example, RCDs and difavtomats have been widely used in Russia for more than a decade, but there is still no single standard for these devices in accordance with GOST 2.755-87, in contrast to automatic switches. It is quite possible that this issue will be settled in the near future. To keep abreast of such innovations, professionals track changes in regulatory documents, amateurs do not need to do this, it is enough to know the decoding of the main designations.

Types of electrical circuits

In accordance with the norms of ESKD, diagrams mean graphic documents on which, using the accepted designations, the main elements or nodes of the structure are displayed, as well as the links that unite them. According to the accepted classification, ten are distinguished, 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 the elements are shown, then - complete.

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

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

Graphic symbols

For each type graphic document their designations are provided, regulated by the relevant regulatory documents. Let us give as an example the main graphic symbols for different types electrical circuits.

Examples of UGO in functional diagrams

Below is a figure depicting the main units of automation systems.

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

Description of designations:

• A - Basic (1) and allowed (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 console or electrical panel.
• С - Display of executive mechanisms (MI).
• D - Influence of IM on the regulatory body (hereinafter RO) when the power is turned off:

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

• E - IM, which additionally has a manual drive. This symbol can be used for any position of the RO specified in clause D.
• F- Received communication lines display:

1. General.
2. No connection when crossing.
3. Connected when crossing.

UGO in single-line and complete wiring diagrams

There are several groups of symbols for these schemes, we will give the most common of them. For complete information, you need to refer to the regulatory documents, numbers state standards will be given for each group.

Power supplies.

The symbols shown in the figure below are used for their designation.

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

Description of designations:

• A - source with constant voltage, its polarity is indicated by symbols "+" and "-".
• V is the electricity icon representing alternating voltage.
• C - the symbol for alternating and direct voltage, used in cases where the device can be powered from any of these sources.
• D - Display battery or galvanic power supply.
• E- Symbol for a multi-cell battery.

Communication lines

The basic elements of electrical connectors are shown below.

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

Description of designations:

• A - General mapping adopted for different 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 diagrams, from several component parts, a break in communication is thus indicated, in such cases "X" is information about where the line will be extended (as a rule, the element number is indicated).
• G - Intersection with no connection.
• H - Connection at the intersection.
• I - Branches.

Designations of electromechanical devices and contact connections

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

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

Description of designations:

• A - symbol of the coil of an electromechanical device (relay, magnetic starter, etc.).
• B - UGO of the receiving part of the electrical thermal protection.
• C - displays the coil of the device with mechanical interlock.
• D - contacts of switching devices:

1. Closing.
2. Openers.
3. Switching.

• E - Symbol to designate manual switches (buttons).
• F - Group switch (switch).

UGO electric machines

Here are some examples of displaying electrical machines (hereinafter EM) in accordance with the current standard.

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

Description of designations:

• A - three-phase EM:

1. Asynchronous (short-circuited rotor).
2. Same as point 1, only in two-speed version.
3. Asynchronous EMs with 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 graphical symbols for these devices can be found in the figure below.

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

Description of designations:

• A - This graphic symbol can be used to designate inductors or transformer windings.
• B - Choke, which has a ferrimagnetic core (magnetic circuit).
• 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 devices and radio components

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

Examples of conventional graphic symbols for electronic components and measuring instruments

Description of designations:

1. Electricity meter.
2. Image of an ammeter.
3. Mains voltage measuring device.
4. Thermal sensor.
5. Constant value resistor.
6. Variable resistor.
7. Condenser (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 fixtures

Consider how electric lamps are displayed on a schematic diagram.

Description of designations:

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

Designation of elements in the wiring diagram

Completing the topic of graphic symbols, we give examples of the display of outlets and switches.

As depicted sockets of other types, it is not difficult to find in the regulatory documents that are available on the network.