Marking of wires according to GOST in electrical circuits. Conventional designation in electrical circuits. Conditional graphic and alphabetic designations. Wire color coding

To understand what is specifically drawn on a diagram or drawing, you need to know the decoding of those icons that are on it. This recognition is also called drawing reading. And to facilitate this lesson, almost all elements have their own conventional icons. Almost, because the standards have not been updated for a long time and some elements are drawn by everyone as best they can. But, for the most part, the conventions in electrical diagrams is in the regulations.

Symbols in electrical circuits: lamps, transformers, measuring instruments, main element base

Normative base

There are about a dozen types of electrical circuits, the number various elements, which can be found there, is in the tens, if not hundreds. To facilitate the recognition of these elements, uniform symbols have been introduced in electrical circuits. All rules are written in GOSTs. There are a lot of these standards, but the main information is in the following standards:

Studying GOSTs is a useful thing, but it takes time, which not everyone has enough of. Therefore, in the article we present the symbols in electrical circuits - the main element base for creating drawings and wiring diagrams, circuit diagrams of devices.

Some experts, having carefully looked at the circuit, can say what it is and how it works. Some may even issue possible problems that may occur during operation. It's simple - they know the circuitry and the element base well, and are also well versed in the symbols of the circuit elements. Such a skill has been developed over the years, and, for "dummies", it is important to remember the most common ones to begin with.

Electrical panels, cabinets, boxes

On the power supply diagrams of a house or apartment, there will necessarily be a designation or a cabinet. In apartments, the terminal device is mainly installed there, since the wiring does not go further. In houses, they can design the installation of a branching electrical cabinet - if a route goes from it to illuminate other buildings located at some distance from the house - baths, guest house. These other designations are in the next picture.

If we talk about images of the "stuffing" of electrical panels, it is also standardized. There are symbols for RCDs, circuit breakers, buttons, current and voltage transformers, and some other elements. They are shown in the following table (there are two pages in the table, scroll by clicking on the word "Next")

Number	Name	Image on the diagram
1	Circuit breaker (automatic)
2	Knife switch (load switch)
3	Thermal relay (overheating protection)
4	RCD (device protective shutdown)
5	Differential automaton (difavtomat)
6	Fuse
7	Switch (knife switch) with fuse
8	Circuit breaker with built-in thermal relay (for motor protection)
9	Current transformer
10	voltage transformer
11	electricity meter
12	Frequency converter
13	Button with automatic opening of contacts after pressing
14	Button with contact opening when pressed again
15	Button with a special switch to disable (stop, for example)

Element base for wiring diagrams

When drawing up or reading a diagram, the designations of wires, terminals, grounding, zero, etc. will also come in handy. This is what a novice electrician simply needs or in order to understand what is shown in the drawing and in what sequence its elements are connected.

Number	Name	Designation electrical elements on the diagrams
1	Phase conductor
2	Neutral (zero working) N
3	Protective conductor ("earth") PE
4	Combined protective and neutral conductors PEN
5	Electric communication line, busbars
6	Bus (if it needs to be selected)
7	Busbar taps (made by soldering)

An example of the use of the above graphics is in the following diagram. Thanks to the letter designations, everything is clear even without graphics, but duplication of information in the diagrams has never been superfluous.

Picture of sockets

On the wiring diagram, the installation locations of sockets and switches should be marked. There are many types of sockets - 220 V, 380 V, hidden and open type installations, with different amount"seating" seats, waterproof, etc. To give the designation of each is too long and useless. It is important to remember how the main groups are depicted, and the number of contact groups is determined by the strokes.

Designation of sockets in the drawings

Sockets for a single-phase 220 V network are indicated on the diagrams in the form of a semicircle with one or more segments sticking up. The number of segments is the number of sockets on one housing (illustrated in the photo below). If only one plug can be plugged into the outlet, one segment is drawn up, if two, two, etc.

If you look at the images carefully, you will notice that conditional image, which is on the right, does not have the horizontal bar that separates the two halves of the icon. This feature indicates that the socket concealed installation, that is, under it it is necessary to make a hole in the wall, install a socket box, etc. The option on the right is for open mounting. A non-conductive substrate is attached to the wall, and the socket itself is attached to it.

Also note that the bottom of the left schematic is crossed out with a vertical line. This indicates the presence of a protective contact, to which grounding is applied. The installation of sockets with grounding is mandatory when turning on a complex household appliances type washing or, oven, etc.

You can’t confuse the symbol of a three-phase socket (for 380 V) with anything. The number of segments sticking up is equal to the number of conductors that are to this device connected - three phases, zero and earth. Total five.

It happens that the lower part of the image is painted over with black (dark). This means that the outlet is waterproof. These are placed on the street, in rooms with high humidity(baths, pools, etc.).

Switch display

The schematic designation of the switches looks like small size a circle with one or more L- or T-shaped branches. Branches in the form of the letter "G" designate an open-mounted switch, with the form of the letter "T" - flush-mounted. The number of taps displays the number of keys on this device.

In addition to the usual ones, they can stand - to be able to turn on / off one light source from several points. Two letters "G" are added to the same small circle from opposite sides. This is the designation of a single-key pass-through switch.

Unlike conventional switches, in these, when using two-button models, one more bar is added parallel to the top one.

Lamps and fixtures

Lamps have their own designations. And the lamps are different. daylight(fluorescent) and incandescent lamps. The diagrams even show the shape and size of the fixtures. In this case, you just need to remember how each type of lamp looks on the diagram.

Radioelements

When reading circuit diagrams of devices, you need to know the symbols for diodes, resistors, and other similar elements.

Knowing the conditional graphic elements will help you read almost any diagram - some kind of device or electrical wiring. The ratings of the required parts are sometimes affixed next to the image, but in large multi-element circuits they are written in a separate table. It contains the letter designations of the circuit elements and the denominations.

Letter designations

In addition to the fact that the elements on the diagrams have conditional graphic names, they have letter designations, which are also standardized (GOST 7624-55).

	Name of electrical circuit element	Letter designation
1	Switch, controller, switch	IN
2	Electric generator	G
3	Diode	D
4	Rectifier	Vp
5	Sound alarm (bell, siren)	Sv
6	Button	Kn
7	incandescent lamp	L
8	Electrical engine	M
9	Fuse	Etc
10	Contactor, magnetic starter	TO
11	Relay	R
12	Transformer (autotransformer)	Tr
13	plug connector	W
14	Electromagnet	Em
15	Resistor	R
16	Capacitor	FROM
17	Inductor	L
18	Control button	Ku
19	Terminal switch	Kv
20	Throttle	dr
21	Phone	T
22	Microphone	Mk
23	Speaker	Gr
24	Battery (galvanic cell)	B
25	Main engine	Dg
26	Cooling pump motor	Before

Please note that in most cases Russian letters are used, but the resistor, capacitor and inductor are indicated in Latin letters.

There is one subtlety in the designation of the relay. They are of different types, respectively marked:

current relay - RT;
power - RM;
voltage - PH;
time - RV;
resistance - RS;
index - RU;
intermediate - RP;
gas - RG;
with time delay - RTV.

Basically, these are only the most conventional symbols in electrical circuits. But most of the drawings and plans you can now understand. If you need to know images of rarer elements, study GOSTs.

If you are doing electrical work, then you definitely need to know the symbols in electrical circuits. The ability to read electrical diagrams is an important quality for fitters, instrumentation and automation fitters, circuit designers. And if you don't have special training, it is unlikely that it will be possible to immediately understand all the subtleties. But it must be remembered that the symbols on the diagrams that are being developed for Russian consumers differ from the generally accepted standards abroad - in Europe, the USA, Japan.

History of designations on diagrams

Back in the Soviet years, when electrical engineering was developing rapidly, it became necessary to classify devices and designate them. That's when it appeared 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 to fully study all the graphic symbols and their standard sizes, notes almost impossible. Therefore, it is necessary to always have a small "cheat sheet" at hand, which will help you navigate the whole variety of electrical components.

Wiring on drawings

Wiring is a generalized concept, it means conductors that have very low resistance. With their help, voltage is transmitted from the source of electricity to consumers. This general concept, as there are many varieties of wiring.

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

Conductors on the diagrams

Even copper tracks on textolite circuit boards are a conductor, you can even say that this is an option electrical wiring. It is indicated on electrical diagrams as a straight connecting line passing from one element to another. In the same way, they are indicated on the diagram and electric wires high-voltage line laid in the fields between the poles. And in apartments, the 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:

Wires.
Cables.
Electrical connections.

The wiring plan is an incorrect definition, since wiring refers to both installation wires and cables. But if we significantly expand the list of elements, as is necessary on 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-in connections designed for non-rigid connection (there is the possibility of manually breaking the connection) of electrical circuits. Symbols on the drawings are strictly regulated by GOST. With its help, rules have been established for designating lighting apparatus and devices and various other electrical consumers on the drawings. Plug-in sockets can be divided into three categories:

Designed for open mounting.
Designed for concealed installation.
A block that includes a socket and a switch.

Single pole sockets.
Bipolar.
Bipolar and protective contact.
Tripolar.
Three-pole and protective contact.

That's enough, there are no features for sockets, there are many options for execution. All devices have a degree of protection, the choice must be made based on the conditions under which it is to be used: humidity level, temperature, the presence of mechanical influences.

Switches on wiring diagrams

Switches are devices that break an electrical circuit. This can be done in automatic or manual mode. The conditional graphic designation by GOST is regulated, as is the case with sockets. The designation depends on the conditions under which the element operates, what design it has, and the degree of protection. There are several types of switch designs:

Single-pole (including double and triple).
Bipolar.
Tripolar.

The diagrams must indicate the parameters of the disconnecting device. And the graphic designation shows which type is used: a simple one with and without fixation, an acoustic device (reacting to cotton) or an optical one. If there is a condition that the lighting turns on at dusk and turns 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-resetting), many types of design, applications, different response speeds, reliability, use in certain conditions describes these devices. The fuse symbol is a rectangle, parallel long side through the center passes the most simple and cheap item capable of protecting the electrical circuit from a short circuit. It should be noted that such components are rarely used in electrical circuit diagrams. Symbols of another type can be found - these are self-restoring fuses, which, after opening the circuit, return to their original state.

The broad name for fuses is a fusible link. It is used in many devices, in electrical distribution boards. You can find them in disposable corks. But there are still devices used in high-voltage ones. They are structurally made of metal tips and the main ceramic part. Inside there is a segment of the conductor (its cross section is selected depending on what maximum current should pass through the circuit). The ceramic body is filled with sand to eliminate the possibility of ignition.

Circuit breakers

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

Plastic case.
Lever to turn on and off.
Bimetal plate - when heated, it deforms.
Contact group - it is included in the electrical circuit.
Arc chute - allows you to get rid of the formation of sparks and arcs during a break in the connection.

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

Grounding on the diagrams

Grounding is the connection of 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, in case of case breakdown, no damage to the device or electric shock will follow, the entire charge will go into the ground. Grounding is of the following types according to GOST:

General concept of grounding.
Clean ground (noiseless).
Protective type of grounding.
Connection to the mass (body) of the device.

Depending on which ground is used in the circuit, the symbol will be different. Important role when drawing up diagrams, the drawing of the element plays, it depends both on the specific section of the circuit and on the type of device.

If we are talking about automotive technology, then there will be a "mass" - a common conductor connected to the body. In the case of house wiring, conductors driven into the ground connected to sockets. In logic circuits, one should not confuse "digital" grounding and conventional grounding - they are different things and they work differently.

Electric motors

On the electrical diagrams of cars, workshops, devices, you can often find electric motors. Moreover, in industry, more than 95% of all used motors 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).

Engines direct current used in automotive technology, control systems. They have two windings - working and excitation. Instead of the latter, some types of motors use permanent magnets. The excitation winding creates a magnetic field. It pushes the rotor of the motor, which has an opposing field - it is created by the winding.

Wire color coding

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

Blue color - zero worker (N).
Yellow with a green stripe - earth wire, protection (PE).
Yellow with green and labels blue color at the edges - the protective and neutral conductors are combined.

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

By functional purpose all conductors are separated as follows:

Black wires - for switching power circuits.
Red wires - for connections of control, measurement, signaling elements.
conductors of blue color- control, measurement and signaling when operating on direct current.
Blue marking is made for zero working conductors.
Yellow and green are ground and protection wires.

Alphanumeric symbols on the diagrams

The terminals have a symbol 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);
SS - equipotential conductor.

Designation on wiring 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 symbols most often used in diagrams and drawings. They can be found in the descriptions. simple devices. If you need to read the circuit 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 electricity. These are inductors. The symbol for a transformer in the diagrams is two coils (depicted as three semicircles) and a core (usually in the form of a straight line). A straight line indicates a core made of transformer steel. But there may be designs of transformers that do not have a core, in which case there is nothing on the diagram between the coils. Such a symbolic designation of elements can also be found in the circuits of radio receiving equipment, for example.

IN last years in engineering, transformer steel is used less and less for the manufacture of transformers. It is very heavy, it is difficult to collect the plates into the core, there is a buzz when loosening. The use of ferromagnetic cores is much more efficient. They are solid, have the same permeability in all areas. But they have one minus - the complexity of the repair, since it is problematic to disassemble and assemble. The symbol of a transformer with such a core is practically no different from that in which steel is used.

Conclusion

These are far from all symbols of 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 standards and imported ones. Crossing conductors on foreign schemes marked with a semicircle. And there is such a thing as a sketch - this is an image of something without complying with the requirements of GOST for elements. Individual Requirements applied to the sketch itself. Such images can be performed for visual presentation future design, electrical wiring. Subsequently, a drawing is drawn up according to it, on which even the designations conditional cables and connections comply with standards.

If for ordinary person the perception of information occurs when reading words and letters, then for locksmiths and installers they are replaced by alphabetic, numeric or graphic symbols. The difficulty is that while the electrician graduates, gets a job, learns something in practice, as new SNiPs and GOSTs appear, according to which adjustments are made. Therefore, do not try to learn all the documentation and immediately. It is enough to gain basic knowledge, and add up-to-date data in the course of working days.

For circuit designers, instrumentation fitters, electricians, the ability to read an electrical circuit is key quality and qualification score. Without special knowledge, it is impossible to immediately understand the intricacies of designing devices, circuits and methods of connecting electrical components.

Types and types of electrical circuits

Before you start studying the existing designations of electrical equipment and its connections, you need to understand the typology of circuits. On the territory of our country, standardization was introduced in accordance with GOST 2.701-2008 of July 1, 2009, according to “ESKD. Schemes. Types and types. General requirements».

Based on this standard, all schemes are divided into 8 types:

United.
Located.
General.
Connections.
Mounting connections.
Complete principal.
Functional.
Structural.

Among the existing 10 species indicated in this document, there are:

Combined.
divisions.
Energy.
Optical.
Vacuum.
Kinematic.
Gas.
Pneumatic.
Hydraulic.
Electrical.

For electricians, it is of the greatest interest among all the above types and types of circuits, as well as the most popular and frequently used in work - the electrical circuit.

The latest GOST, which came out, is supplemented by many new designations, relevant today with the code 2.702-2011 of 01/01/2012. The document is called "ESKD. Rules for the implementation of electrical circuits ”, refers to other GOSTs, among which are those mentioned above.

The text of the regulation sets out clear requirements in detail for electrical circuits of all types. Therefore, be guided by installation work with electrical circuits follows exactly this document. The definition of the concept of an electrical circuit, according to GOST 2.702-2011, is as follows:

"Under the electrical circuit should be understood a document containing the symbols of the parts of the product and / or individual parts with a description of the relationship between them, the principles of operation from electrical energy."

After the definition, the document contains the rules for the implementation on paper and in software environments of the designations of contact connections, wire marking, lettering and graphic representation of electrical elements.

It should be noted that more often in home practice only three types of electrical circuits are used:

Mounting- for the device is displayed printed circuit board with the arrangement of elements with a clear indication of the place, denomination, the principle of fastening and leading to other details. Wiring diagrams for residential premises indicate the number, location, rating, connection method and other precise instructions for installing wires, switches, lamps, sockets, etc.
Fundamental- they indicate in detail the connections, contacts and characteristics of each element for networks or devices. Distinguish between full and linear circuit diagrams. In the first case, control, control of elements and the power circuit itself are depicted; in a linear scheme, they are limited only to a chain with the image of the remaining elements on separate sheets.
Functional- here, without detailing the physical dimensions and other parameters, the main components of the device or circuit are indicated. Any detail can be represented as a block with a letter designation, supplemented with links to other elements of the device.

Graphic symbols in electrical circuits

Documentation, which indicates the rules and methods for graphic designation of circuit elements, is represented by three GOSTs:

2.755-87 - graphic symbols for contact and switching connections.
2.721-74 - graphic symbols for parts and assemblies of general use.
2.709-89 - graphic symbols in electrical diagrams of circuit sections, equipment, contact connections of wires, electrical elements.

In the standard with the code 2.755-87, it is used for diagrams of single-line electrical panels, conditional graphic images (UGO) of thermal relays, contactors, knife switches, circuit breakers, and other switching equipment. There is no designation in the standards of difavtomatov and RCD.

On the pages of GOST 2.702-2011, these elements are allowed to be depicted in an arbitrary order, with explanations, decoding of the UGO and the circuit of difavtomatov and RCD itself.
GOST 2.721-74 contains UGOs used for secondary electrical circuits.

IMPORTANT: To designate switching equipment, there is:

4 base images UGO

9 functional signs of UGO

*UGO*	*Name*
	Arc quenching
	No self-return
	self-return
	Limit or travel switch
	With automatic actuation
	switch-disconnector
	Disconnector
	Switch
	Contactor

IMPORTANT: Designations 1 - 3 and 6 - 9 are applied to fixed contacts, 4 and 5 are placed on moving contacts.

Basic UGOs for single-line electrical switchboard diagrams

*UGO*	*Name*
	Thermal relay
	contactor contact
	Knife switch - load switch
	Automatic - automatic switch
	Fuse
	Differential circuit breaker
	RCD
	voltage transformer
	Current transformer
	Knife switch (load switch) with fuse
	Motor protection circuit breaker (with built-in thermal relay)
	Frequency converter
	electric meter
	Normally open contact with "reset" button or other push button switch, with reset and opening via a special drive of the control element
	Normally open contact with pushbutton, with reset and opening by retracting the button of the operating element
	Normally open contact with pushbutton, with reset and opening by repeated pressing of the button of the operating element
	Normally open contact with pushbutton, with reset and automatic opening of the operating element
	N/O contact with delayed action, which is initiated on return and operation

	N/O contact with delayed action, which is initiated only when triggered
	Slow-acting make contact that is activated on return and trip
	N/O contact with delayed action that only trips on return
	N/O contact with delayed action that only closes when triggered
	Timing relay coil
	photorelay coil
	Pulse relay coil
	General designation of a relay coil or contactor coil
	Indicator lamp (light), lighting
	motor drive
	Terminal (collapsible connection)
	Varistor, surge arrester (surge arrester)
	Discharger
	Socket (plug connection): Pin Nest
	A heating element

Designation of electrical measuring instruments for characterizing circuit parameters

GOST 2.271-74 adopted the following designations in electrical panels for tires and wires:

Letter designations in electrical circuits

The standards for the letter designation of elements on electrical diagrams are described in the GOST 2.710-81 standard with the title of the text “ESKD. Alphanumeric designations in electrical circuits. The mark for difavtomatov and RCD is not indicated here, which is prescribed in clause 2.2.12 of this standard as a designation with multi-letter codes. The following letter codings are accepted for the main elements of electrical panels:

*Name*	*Designation*
Automatic switch in the power circuit	QF
Automatic switch in the control circuit	SF
Circuit breaker with differential protection or difavtomat	QFD
Breaker or load switch	QS
RCD (residual current device)	QSD
Contactor	KM
Thermal relay	F, KK
Time relay	KT
Voltage relay	KV
impulse relay	KI
photorelay	KL
OPN, arrester	FV
fuse	FU
voltage transformer	TV
Current transformer	TA
Frequency converter	USD
Ammeter	PA
Wattmeter	PW
Frequency meter	PF
Voltmeter	PV
Active energy meter	PI
Reactive energy meter	PK
heating element	EK
Photocell	BL
lighting lamp	EL
Light bulb or indicator light	HL
Plug connector or socket	XS
Switch or circuit breaker in control circuits	SA
Pushbutton switch in control circuits	SB
Terminals	XT

Image of electrical equipment on the plans

Despite the fact that GOST 2.702-2011 and GOST 2.701-2008 take into account such a type of electrical circuit as a "layout" for the design of structures and buildings, it is necessary to be guided by the standards of GOST 21.210-2014, which indicate "SPDS.

Images on the plans of conditional graphic wiring and electrical equipment. The document establishes UGO on plans for laying electrical networks of electrical equipment (lamps, switches, sockets, electrical panels, transformers), cable lines, busbars, tires.

The use of these symbols is used to draw up drawings of electrical lighting, power electrical equipment, power supply and other plans. The use of these designations is also used in fundamental single line diagrams electrical boards.

Conditional graphic images of electrical equipment, electrical devices and electrical receivers

The contours of all depicted devices, depending on the information richness and complexity of the configuration, are taken in accordance with GOST 2.302 on the scale of the drawing according to the actual dimensions.

Conditional graphic designations of wiring lines and conductors

Conditional graphic images of tires and busbars

IMPORTANT: The design position of the bus duct must exactly match on the diagram with the place of its attachment.

Conditional graphic images of boxes, cabinets, shields and consoles

Conditional graphic symbols of switches, switches

On the pages of the GOST 21.210-2014 documentation for push-button switches, dimmers (dimmers), a separate designation is not provided. In some schemes, according to clause 4.7. normative act, arbitrary designations are used.

Conventional graphic designations of socket outlets

Conditional graphic designations of lamps and spotlights

The updated version of GOST contains images of luminaires with fluorescent and LED lamps.

Conditional graphic designations of control and management devices

Conclusion

The given graphic and letter images of electrical components and electrical circuits are not complete list, since the regulations contain many special characters and ciphers that are practically not used in everyday life. To read electrical circuits, you will need to take into account many factors, first of all, the country of the manufacturer of the device or electrical equipment, wiring and cables. There is a difference in marking and symbol on the diagrams, which can be quite confusing.

Secondly, you should carefully consider such areas as the intersection or lack of a common network for wires located with an overlay. On foreign diagrams, if the bus or cable does not have a common power supply with intersecting objects, a semicircular continuation is drawn at the point of contact. This is not used in domestic schemes.

If the diagram is depicted without complying with the standards established by GOSTs, then it is called a sketch. But for this category there are also certain requirements, according to which, according to the above sketch, an approximate understanding of the future electrical wiring or device design should be drawn up. Drawings can be used to draw up more accurate drawings and diagrams from them, with the necessary designations, markings and scales.

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

Regulations

Given the large number of electrical elements, for their alphanumeric (hereinafter referred to as BO) and conventionally graphic designations (UGO), a number of regulatory documents have been developed that exclude discrepancies. Below is a table that shows the main standards.

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

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

It should be borne in mind 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 difautomatic devices 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 possible that this issue will be resolved in the near future. To keep abreast of such innovations, professionals track changes in regulatory documents, amateurs do not have 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 are understood as graphic documents on which, using the accepted designations, the main elements or components of the structure are displayed, as well as the links that unite them. According to the accepted classification, ten types of circuits 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 it is complete.

If the drawing shows the wiring of the apartment, then the location 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 not true, since the latter displays 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

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

Examples of UGOs 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 - Main (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.
C - Display of actuators (IM).
D - Influence of MI on the regulatory body (hereinafter RO) when the power is turned off:

RO opens.
RO closure
The position of the RO remains unchanged.

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

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

UGO in single-line and complete electrical circuits

For these schemes, there are several groups of symbols, we will give the most common of them. For getting complete information it is necessary to refer to the regulatory documents, the numbers of state standards will be given for each group.

Power sources.

For their designation, the symbols shown in the figure below are accepted.

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

Description of symbols:

A - a source with a constant voltage, its polarity is indicated by the symbols "+" and "-".
B is an electricity icon that displays alternating voltage.
C - symbol for AC and DC voltage, used when the device can be powered from any of these sources.
D - Display battery or galvanic power supply.
E- Symbol for a battery consisting of several batteries.

Communication lines

The basic elements of electrical connectors are shown below.

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

Description of symbols:

A - General display adopted for various types of electrical connections.
B - Current-carrying or grounding bus.
C - Shielding designation, can be electrostatic (marked with the symbol "E") or electromagnetic ("M").
D - Earth symbol.
E - Electrical connection with the body of the device.
F - On complex schemes, from several constituent parts, thus indicating a break in communication, 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 - Connection at the 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.

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

Description of symbols:

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

Closing.
Opening.
Switching.

E - Symbol for the designation of manual switches (buttons).
F - Group switch (knife switch).

UGO electric machines

Let us give some examples, mappings electrical machines(hereinafter 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:

Asynchronous (short-circuited rotor).
The same as point 1, only in a two-speed version.
Asynchronous EM with phase design of the rotor.
Synchronous motors and generators.

B - Collector, powered by DC:

EM with permanent magnet excitation.
EM with excitation coil.

UGO transformers and chokes

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

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

Description of symbols:

A - This graphic symbol may indicate 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 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 that you look at GOSTs 2.729 68 and 2.730 73.

Examples of conventional graphic symbols for electronic components and measuring instruments

Description of symbols:

Electricity meter.
Image of an ammeter.
Device for measuring mains voltage.
Thermal sensor.
Resistor with fixed value.
Variable resistor.
Capacitor (general designation).
electrolytic capacity.
Diode designation.
Light-emitting diode.
Image of a diode optocoupler.
UGO transistor (in this case npn).
Fuse designation.

UGO lighting fixtures

Let's consider how circuit diagram electric lamps are displayed.

Description of symbols:

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

Designation of elements in the wiring diagram

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

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

Reading schemes is impossible without knowledge of the conditional graphic and letter designations of 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 “how someone came up with it”. And this is the difficulty of reading the schemes of new devices. But, basically, the symbols in electrical circuits are described and are well known to many.

Two types of designations are often used on diagrams: graphic and alphabetic, and denominations are also often put down. According to these data, many can immediately tell how the scheme works. This skill develops over years of practice, but first you need to understand and remember the symbols in electrical circuits. Then, knowing the work of each element, you can imagine the final result of the device.

Drawing up and reading various diagrams usually requires different elements. There are many types of circuits, but in electrics the following are commonly used:

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

Basic images and functional features

Switching devices (switches, contactors, etc.) are built on contacts of various mechanics. There are make, break, changeover contacts. The closing contact is open in the normal state, when it is switched to the working state, the circuit closes. The NC contact is normally closed, and under certain conditions it works, opening the circuit.

The changeover contact can be two or three positions. In the first case, one circuit works, then another. The second 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 only moving contacts perform. They are shown in the photo below.

The main functions can only be performed by fixed contacts.

Symbols for single-line diagrams

As already mentioned, only the power part is indicated on single-line diagrams: RCDs, automata, difautomats, sockets, knife switches, switches, etc. and connections between them. The designations of these conditional 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 trifle. For example, an automatic machine (circuit breaker) and a knife 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 knife switch is the shape of the icon on the fixed contact. A very small difference, but the device and its functions are different. All these little things need to look closely and remember.

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

The situation is approximately the same with the coils of relays and contactors. They look like a rectangle with small graphic additions.

In this case, it is easier to remember, since there are quite serious differences in appearance additional icons. With a photorelay, it’s quite simple - the rays of the sun are associated with arrows. The impulse 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". plug connection(like a socket / plug or socket / plug) looks like two brackets, and collapsible (like a terminal block) - circles. Moreover, the number of pairs of checkmarks or circles indicates the number of wires.

Image of tires and wires

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

There are separate images for buses, but they are used if it is necessary to separate them graphically from communication lines, wires and cables.

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

How switches, switches, sockets are depicted

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

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

There are separate designations for two-gang and three-gang switches. In the documentation, they are called "double" and "triple", respectively. There are differences for cases with varying degrees protection. In rooms with normal conditions operation put switches with IP20, maybe up to IP23. In wet rooms(bathroom, swimming pool) or outdoors, the degree of protection must be at least IP44. Their images differ in that the circles are filled in. So it's easy to tell them apart.

There are separate images for switches. These are switches that allow you to control the on / off of the light 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, 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 an increased protection housing (IP44 and higher), the middle is tinted in a dark color.

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

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

Luminaires on the diagrams

This section describes the conventions in electrical diagrams. various lamps and lamps. Here is the situation with the designations of the new element base better: there are even signs for LED lamps and fixtures, compact fluorescent lamps (housekeepers). It is also good that the images of lamps of different types are significantly different - it is difficult to confuse. 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 lamp of a fluorescent type and an LED one 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 hanging 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 circuit diagrams

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

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

Letter symbols in electrical circuits

In addition to graphic images, the elements on the diagrams are signed. It also helps to read diagrams. Next to the letter designation of the element is often its serial number. This is done so that later it was 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. Extracts from there with the table below.

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