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 varieties of electrical circuits, the number of different elements that 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 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 - a bathhouse, a 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 (residual current device)
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 of 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 a different number of "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 single-phase network 220 V 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 closely, notice that the symbolic image on the right does not have the horizontal bar that separates the two halves of the icon. This feature indicates that the socket is flush-mounted, that is, it is necessary to make a hole in the wall under it, install a socket box, etc. The option on the right is for surface 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 with anything three-phase socket(at 380 V). The number of segments sticking up is equal to the number of conductors that are connected to this device - three phases, zero and ground. 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 switches looks like a small 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. They stand in it letter designations circuit elements and ratings.

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	AT
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	Telephone	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 different type, 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.

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

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

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

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

Conductors, lines, cables

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

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

As you can see, already at the stage of studying seemingly simple wires, there are complex and varied designations of their varieties and interactions.

Image of junction boxes, shields

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

Image of wires, lamps and plugs

It makes no sense to start memorizing all these icons. They themselves will be deposited in the mind after studying various drawings, in which from time to time you will have to look into this table.

Network components

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

By learning their designation, you can easily understand the arrangement of wiring in your room, or even design your own wiring plan, taking into account immediate needs.

Designation of a single-gang switch, a two-gang switch and a pass-through switch

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

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

An example of a wiring diagram for a small apartment

A little practice to remember

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

Having the outline of graphic symbols, you can connect them with lines, and get a wiring diagram in the room. Since the wires are hidden in the wall covering, the installation drawing cannot be drawn, but the wiring diagram will be correct.

Example of a simple circuit

The oblique lines indicate the number of conductors in the line. The arrows indicate the outputs to the shield with circuit breakers and RCDs. Line of blue color means connecting with a two-wire cable to the distribution box, from which three wires go to the switch and the lamp.

Black shows 3-wire wiring with protective conductor RE. This figure is for illustration purposes only. To design complex electrical systems, you need to take a whole course of a higher specialized educational institution.

But, having learned a few common symbols, you can freehand draw the wiring of a room, garage or an entire house, and work on it, embodying it in reality.

RCD, automatic devices, electrical panel

To complete the picture, we still need to clarify the notation junction boxes, circuit breaker, RCD, counter.

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

Protective systems

To be able to understand the arrangement of all wiring country house(not only power grids), you also need to study the means of lightning protection, zero, phases, the motion sensor icon and other signaling means of the POS (fire and burglar alarm).

scheme of lightning protection of a country house with a wire lightning rod installed on the roof

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

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

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

This figure shows the plan of the cottage with the depicted wiring diagram for various fire and security alarm sensors.

An example of a cottage plan

This article shows that part of the designations that relates to the arrangement of a house or apartment. For a more complete acquaintance with the graphic symbols of electrical engineering and other industries, you need to study GOST and various reference books.

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

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 a key quality and qualification indicator. 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. Scheme. Types and types. General requirements».

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

1. United.
2. Located.
3. General.
4. Connections.
5. Mounting connections.
6. Complete principal.
7. Functional.
8. Structural.

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

1. Combined.
2. divisions.
3. Energy.
4. Optical.
5. Vacuum.
6. Kinematic.
7. Gas.
8. Pneumatic.
9. Hydraulic.
10. 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, it is this document that should be guided during installation work with electrical circuits. 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 linear diagram 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 pressing the operating element button again
	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
	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 the schematic single-line diagrams of electrical panels.

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 circuits, in the absence of a bus or cable general nutrition 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 based on them, with the necessary designations, markings and scales.

When carrying out electrical work, an important nuance is the availability of knowledge in this area. This will help connect the object to power as safely as possible. One of the most important devices in the electrical circuit is considered a circuit breaker. Its task is to turn off the power when short circuit or network congestion. you can in our online store. In the article we will consider the symbol of the circuit breaker in the diagram.

Designation of machines

When creating drawings of electrical circuits, it is customary to designate the circuit breaker on the diagram in accordance with GOST 2.702-2011. It contains all the necessary rules. State standards in a single-line diagram require the representation of protective equipment in such combinations:

The motor protection device is depicted differently. The designation of circuit breakers on the diagram looks, in addition to graphic pointers, using an alphabetic symbol. The device, depending on the characteristics, is depicted in the following options:

The first is a control machine that protects power circuits, regulates the operation of machines and equipment. The next one is for the production, transmission, transformation and distribution of electricity. The latter is a difavtomat, which is used to ensure the high safety of electrical appliances that are often used.

Circuit Breaker Classification

The selection of an electrical device occurs according to the scheme. The device must meet the stated requirements. GOST R 50030.2-99 shows that all circuit breakers are classified into several varieties according to criteria such as:

Machines are classified into the following types:

• switches with energy storage;
• emergency;
• current release;
• blocker;
• unattended and serviced;
• automatic control or manual;
• with a fuse;
• gas, air, vacuum;
• current-limiting, etc.

In addition, devices are distinguished by the number of poles (up to 4). For example, this is a bipolar protective device. Devices are also distinguished by rated frequency, type of current and number of phases.

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 to both wiring diagrams or power circuits, as well as 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 regulates the norms according to which 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, 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 only the power part of the installation is displayed on the diagram, then it is called single-line, if all elements are shown, then it is called complete.

If the drawing shows the wiring of the apartment, then the locations of 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:

1. RO opens.
2. RO closure
3. The position of the RO remains unchanged.

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

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

UGO in single-line and complete electrical circuits

For these schemes, there are several groups of symbols, we will give the most common of them. For complete information, you must 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 is a variable symbol and constant voltage, is 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 mapping adopted for various kinds 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 diagrams, from several components, a break in communication is indicated in this way, 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:

1. Closing.
2. Opening.
3. 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:

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

• B - Collector, powered by DC:

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

UGO transformers and chokes

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

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

Description of symbols:

• A - This graphic symbol 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:

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

UGO lighting fixtures

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

Description of symbols:

• BUT - General image incandescent lamps (LN).
• B - LN as a signaling device.
• C - Type designation of gas 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

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.