The designation of the withdrawable circuit breaker on the scheme GOST. Ouzo symbol on the diagram. Symbols on electrical diagrams according to GOST: alphabetic, graphic

Wiring diagram- this is a text that describes the content and operation of an electrical device or a set of devices with certain symbols, which allows short form express this text.

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

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

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

In addition, in the conventional graphic symbols on electrical circuit diagrams additionally, special signs are used to explain the features of the operation of one or another element of the circuit.

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

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

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

Standards. Conventional graphic symbols on electrical and automation diagrams:

GOST 2.710-81 Alphanumeric designations in electrical circuits:

Reading schemes is impossible without knowledge of the conditional graphic and letter designations of elements. Most of them are standardized and described in normative 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, but when certain conditions it works by 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, on single line diagrams only the power part is indicated: RCDs, automata, differential automata, 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 a collapsible one (like a terminal block) looks like circles. Moreover, the number of pairs of checkmarks or circles indicates the number of wires.

Image of tires and wires

In any 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 circuits: sockets different type installation (open, hidden)

Having understood the logic of the designation and remembering some initial data (what is the difference conditional image sockets of 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 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 shown, but, in addition, there is a large number of radio elements: resistors, capacitors, 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.

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 and automation fitters, electricians, the ability to read an electrical circuit is a key quality and indicator of qualification. 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, 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."

Once defined, the document contains rules for the implementation on paper and in software environments of notation contact connections, wire markings, letters 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 part 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 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)
	A frequency converter
	electricity 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 push button switch, 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, which 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 (device protective shutdown)	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
A 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 the foreign schemes 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.

However, the designation of RCDs and difavtomatov in GOST is missing. Drawing in AutoCAD is conveniently performed using blocks and dynamic blocks. Any element on the electrical circuits is assigned not only a graphic designation, but also an alphabetic designation indicating the position number.

But lately there has been a tendency to use ERE and foreign-made components. As a rule, information about the applied ERE is indicated in reference books and specifications - a list of these elements. The connection of the list of ERE components with their conditional graphic designations is carried out through reference designations.

At the same time, the meaning of each geometric image in the symbol in many cases depends on the combination with which other geometric symbol it is used. The designations on the drawings and diagrams of elements of general use refer to qualification ones, establishing the type of current and voltage. Available in stores Various types ERI and ERE with foreign designations.

GOST 2.755-87 ESKD. Conditional graphic designations in electrical circuits. Switching devices and contact connections

If the dimensions are not indicated in numbers in GOST, then this element is drawn somewhere in the document on graph paper. On the case of ammeters and voltmeters there is conditional icons and among them an asterisk. Indicates connection to DC voltage, parenthesis - use in horizontal position etc.

How is the difavtomat indicated on the diagram?

There is such a useful book, they still used it in the technical school. A bit outdated but still relevant today. Just as it is impossible to read a book without knowing the letters, so it is impossible to understand any electrical drawing without knowledge of symbols. Moreover, GOST, SNiP and other standards are periodically updated.

Before talking about the symbols on the diagrams, you need to figure out what types and types of diagrams are. On July 1, 2009, GOST 2.701-2008 “ESKD. Scheme. Types and types. General performance requirements”. As an electrician, I am interested in circuits of the type "Electrical Scheme". In addition to GOST 2.755-87, for the completeness of the scheme, you will need to use images from GOST 2.721-74 (mainly for secondary circuits).

On various sites and forums on the Internet, they discussed for a long time how to properly designate an RCD and a difavtomat. GOST 2.710-81 in clause 2.2.12. RCD and difavtomat. I added the letter D to the two-letter designation of the knife switch and received the designation RCD. I did the same with the difavtomat.

These symbols are used when drawing power supply, power electrical equipment, electric lighting and other drawings. Laying tires and bus ducts. I am glad that images have been added to the updated version of GOST LED lamps and fixtures with compact fluorescent lamps. In order to read any text, you need to know the alphabet and reading rules.

So, for example, there are three types of contacts - closing, opening and switching. Additional signs allow you to find the contacts of control buttons, time relays, limit switches, etc. on the diagram. Individual elements on electrical diagrams have not one, but several designations on the diagrams. Each of the designations can be used in certain cases.

Types and types of electrical circuits

UGO of all contacts is allowed to be depicted only in mirror or rotated by 90 ° positions. The last two UGOs on electrical circuits are used in cases where it is necessary to show a type of switching product, the contacts of which usually do not have these properties. The conventional graphic designation of switches on electrical circuits (Fig. 3) is built on the basis of the symbols of normally open and normally closed contacts.

The letter code of products of this group is determined by the switched circuit and the design of the circuit breaker. Switches Q1 and Q2 are used to switch power circuits. Among the many of this documentation, you can find instances in which there are differences between the conventions of certain elements. For example, in different projects the same switching device can be graphically displayed in different ways.

Many users may disagree with me, arguing that why do I need to know GOST, I just install sockets and switches in apartments. Schemes must be known to design engineers and professors at universities. In addition, incorrect data can mislead third-party specialists involved in electrical installation and cause difficulties in the installation of electrical communications.

So, above, I presented the main documents according to which the designations in electrical circuits are regulated. The current GOST does not put forward any special requirements for the rules for the compilation and use of RCD graphic symbols. For example, let's look at what designations are applied to the case of the devices themselves. To avoid confusion, I suggest that you jointly develop a universal version of the designation of the RCD, which can be used as a guide in almost any working situation.

Regarding the designations of difavtomatov in GOST, there is also no data at the moment. But, based on the above scheme, the difavtomat can also be graphically represented in the form of two elements - an RCD and a circuit breaker. So, for example, according to GOST 2.710-81 circuit breakers it is customary to denote by a special alphanumeric reference designation in this way: QF1, QF2, QF3, etc.

Fuses in the diagrams are designated as FU with the corresponding serial number. Similarly, as with graphic symbols, there is no specific data in GOST 2.710-81 on how to perform the alphanumeric designation of RCDs and differential automata on the diagrams. How to be in that case? In this case, many masters use two designations. The code combination QF stands for Q - “switch or knife switch in power circuits”, F - “protective”, which may well be applicable not only to conventional machines, but also to differential machines.

I very often met on real circuits such a designation QD1 - for residual current devices, QFD1 - for differential automata. Each designer can depict these elements on the diagrams at his own discretion.

I think that soon it will be reissued and the RCD designation will be added. Functional diagrams used to study the principles of operation of the installation, as well as when setting up, adjusting, monitoring and repairing.

Conventional graphic designations of switching products - switches, switches and electromagnetic relays are built on the basis of contact symbols: closing (Fig. 1, b), opening (c, d) and switching (d, f). Contacts that simultaneously close or open two circuits are designated as shown in fig. 1, f, i.

Fig.1. Conventional designation of switches and switches

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

The standardized notation also provides for the reflection of such design features, as the non-simultaneity of the operation of one or more contacts in the group, the absence or presence of their fixation in one of the positions. So, if it is necessary to show that the contact closes or opens before others, the symbol of its moving part is supplemented with a short stroke directed towards the operation (Fig. 2, a, b), and if later, with a stroke directed to reverse side(Fig. 2, c, d). The absence of fixation in the closed or open positions (self-return) is indicated by a small triangle, the apex of which is directed towards the initial position of the movable part of the contact (Fig. 2, e, f), and fixation is indicated by a circle on the symbol of its fixed part (Fig. 2, g, and). The last two designations are used in cases where it is necessary to show a type of switching product, the contacts of which usually do not have these properties.

Fig.2. Symbol for switching products

The conventional graphic designation of switches (Fig. 3) is built on the basis of the symbols of normally open and normally closed contacts. This means that the contacts are fixed in both positions, i.e., they do not have a self-return.

Fig.3. Conventional designation of switches

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

If there are several contacts in the switch, the symbols of their moving parts are placed in parallel and connected by a line mechanical connection. As an example, in fig. 3 shows the symbolic graphic designation of the switch SA2, containing one breaking and two closing contacts, and SA3, consisting of two closing contacts, and one of which (in the figure - right) closes later than the other. Switches Q1 and Q2 are used to switch power circuits. Contacts Q2 are mechanically connected to any control, as evidenced by a segment of the dashed line. When displaying contacts in different areas schemes, their belonging to one switching product is traditionally reflected in an alphanumeric reference designation (SA4.1, SA4.2, SA4.3).

Similarly, on the basis of the symbol of the switching contact, the conventional graphic symbols of on-off switches are built (Fig. 4, SA1, SA4). If the switch is fixed not only in the extreme, but also in the middle (neutral) position, the symbol of the moving part of the contact will interfere between the symbols of the fixed parts, the possibility of turning it in both directions is indicated by a dot (SA2 in Fig. 4).

Conventional graphic symbols on electrical circuit diagrams

The same is done if it is necessary to show on the diagram a switch that is fixed only in the middle position (see Fig. 4, SA3).

Fig.4. Conventional designation of two-position switches

A distinctive feature of the designation of push-button switches and switches is the button symbol connected to the designation of the moving part of the contact by a mechanical connection line (Fig. 5). Moreover, if the conditional graphic designation is built on the basis of the main contact symbol (see Fig. 1), this means that the switch (switch) is not fixed in the pressed position (when the button is released, it returns to its original position). If it is necessary to show fixation, use the symbols of contacts with fixation specially designed for this purpose (Fig. 6). Return to the original position when another button of the switch is pressed is shown in this case by the sign of the locking mechanism, attaching it to the symbol of the movable part of the contact from the side opposite to the symbol of the button (see Fig. 6, SB1.1, SB1.2). If the return occurs when the button is pressed again, the sign of the locking mechanism is depicted instead of the mechanical connection line (SB2).

Fig.5. Conventional designation of push-button switches and switches

Fig.6. Conventional designation of switches and switches with fixing

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

Fig.7. Conventional designation of multi-position switches

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

Fig.8. Symbol for multi-position switches with complex switching

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

The wire is an efficient current conductor.

Wire without connection denoted by the "hump method".

Wire with connection- indicates the physical connection of the wires, which allows the passage of current.

Direct current (DC)- an electric current that does not change in magnitude and direction over time.

Alternating current (AC)- an electric current that changes in magnitude and direction over time.

Battery- supply of electricity from one or more batteries.

Cell— limited supply of electricity.

grounding- 0 W or ground depending on the circuit.

Diode- limits the direction of the current so that it flows in only one direction.

Light-emitting diode(LED) - A semiconductor diode that emits incoherent light when an electric current is passed through it.

Photodiode- a semiconductor diode with the property of one-sided photoconductivity when exposed to optical radiation.

Zener diode ( zener diode) - semiconductor device designed to stabilize the voltage.

Resistor- a passive element of an electrical circuit designed to resist electric current.

Variable resistor- a variable resistor in a rheostatic connection.

Variable resistor with three leads, used to limit the current in an electrical circuit.

Trimmer resistor- trimming resistor in a rheostat connection.

Thermistor- a semiconductor resistor, which uses the dependence of the electrical resistance of a semiconductor material on temperature.

Light Dependent Resistor A resistor whose resistance decreases or increases depending on the intensity of the light falling on it.

Heater- Converted electricity into heat.

Fuse- the simplest device for protecting electrical circuits from overloads and short circuit currents.

light lamp- electricity converted into light.

Lamp, Indicator - electricity converted into light for the purpose of warning.

Motor- electricity converted into mechanical energy.

Inductor(Coil, Solenoid) - a coil of coiled insulated conductor that creates a magnetic field when current passes through it.

Oscilloscope- a device that shows the shape of the voltage over time.

Galvanometer- a device that measures very small alternating and direct currents (less than 1mA).

Voltmeter- a device for measuring emf or voltage in electrical circuits.

Ohmmeter- a direct reading device.

Symbols in electrical circuits (gost 7624-55)

Its main function is to determine the active resistance of the electric current.

Ammeter- a device for measuring current strength in amperes.

And- a logic circuit that requires two inputs, if both are high, then the output is high, in all other cases it produces low. (00=0 01=0 10=0 11=1)

Or- a logic circuit that requires two inputs, if either or both are high, then the output is high, in all other cases it produces a low. (00=0 01=1 10=1 11=1)

NAND- a logical circuit that requires two inputs and leads to opposite results AND. (00=1 01=1 10=1 11=0). An interesting note, on your computer the central processing unit (CPU) is built entirely of gates.

Non-OR- a logic circuit that requires two inputs and leads to opposite OR results. (00=1 01=0 10=0 11=0).

Not- a logic circuit that requires one input, if it is high, then the output is low. (0=1 1=0).

Xor- a logic circuit that requires two inputs, if any but not both are high, then the output is high, in all other cases it produces low. (00=0 01=1 10=1 11=0)

NXOr is a logic circuit that requires two inputs and results in opposite XOR results. (00=1 01=0 10=0 11=1)

Switch (SPST)- an electrical switching device that serves to close and open an electrical circuit.

Two Way Switch (SPDT) An electrical switching device that allows current to flow in one of two ways.

Switch(push to connect) - A switch that allows current to flow only in the closed position.

Return to the open position.

Switch(push to break) - A switch that allows current to flow only in the closed position. Return to closed position.

Switch, Double On/Off (DPST) is a two-pole switch.

Switch, Reversing (DPDT) - A switch that allows current to flow from two wires in two different paths.

Disk A switch that allows current to flow through multiple paths from a single source.

Relay- a device for closing and opening various sites electrical circuits for given changes in electrical or non-electrical input quantities.

NPN transistor — bipolar transistor. Consists of three differently doped semiconductor layers (emitter E, base B and collector C). In this case, the NPN transistor passes current from the collector to the emitter.

PNP transistor- bipolar transistor. Consists of three differently doped semiconductor layers (emitter E, base B and collector C). In this case, the PNP transistor passes current from the emitter to the collector.

Photo Transistor- used as a current amplifier or switch, which is activated by light.

Capacitor, Permanent - a device for the accumulation of charge and energy of the electric field.

Capacitor, Polar - an electrolytic capacitor that has a connection polarity.

Capacitor, Trimmer - variable capacitor. In fact, it is a variable capacitor, not designed for frequent rotation.

Capacitor, Variable - its capacity can vary within the specified limits.

Piezo transducer(Piezo) is a device that converts electricity into sound.

Transformer- two or more inductive windings designed to convert a system (voltages) of direct or alternating current into one or more other systems (voltages), without changing the frequency.

Speaker

Earphone(i) - an apparatus that converts electrical energy into sound.

Microphone A device that converts electrical energy into sound.

Amplifier- amplifier of electrical signals.

call A device that converts electrical energy into sound.

Horn A device that converts electrical energy into sound.

Antenna— transmits or receives radio signals.

The following symbols are accepted in electrical circuits:

Name	Designation
Wire, cable, bus, electrical communication line
Branch of one wire, cable, bus
Three-phase generator
Three-phase winding connected in a star
Three-phase winding connected in delta
Three-phase winding connected in a star with a dedicated neutral (midpoint)
grounding
Ground wire connection
Insulation damage between wires
Damage to the insulation on the housing
Ground insulation failure
Reactor
Tubular arrester
Surge arrester valve and magnetic valve
Current relay
Watt hour meter
Ammeter
fuse
Resistor constant
Inductor, coreless choke
Fixed Capacitor
Plug contact: pin nest
A chain of two wires, cables, tires	single line	Multiline
A chain of three wires, cables, tires
4-wire circuit
Single current transformer secondary winding	Form I	Form II
Current transformer with one core and two secondary windings
Measuring voltage transformer	Form I	Form II
Three-phase transformer with a magnetic core with a star-star winding connection with a neutral (middle) point
Three-pole disconnector	single line	Multiline
Three-pole switch

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Creation of schematic diagrams. Designation of elements on circuit diagrams

Introduction.

Reading and drawing circuit diagrams is an integral part of an industrial engineer. Standards for drawing up circuit diagrams and graphical display of elements were actively used in the USSR and other countries. The basis here was one system design documentation ESKD. In this article, I want to introduce the basic principles and art of drawing up circuit diagrams. At the same time, I draw your attention to the fact that this will not be a description of the standards, I would like to present the current practice that is used in the designation of elements and the compilation of high-quality circuit diagrams.

§one. The art of concept drawing.

There are few good designs. Create good scheme long and tedious, because you always have to remember that you are creating a circuit for a person, and not just describing a device according to a certain standard. Most of the schemes that are created according to ESKD by designers and engineers of enterprises are simply ugly. That's why I call circuit diagramming an art. Skillfully designed scheme greatly facilitates the work with the device. Therefore, I advise you to redraw diagrams for devices that you service constantly.

Basic principles for drawing up circuit diagrams:
• the scheme is needed by a person, not a device;
• a balance is needed between detail and readability;
• it is necessary to graphically highlight the essence of the device and the importance of certain areas;
• a look at the diagram should show a clear path to its main functions

§2.

De facto types of industrial circuit diagrams.

Currently, two types of representation of circuit diagrams are used:
• a large diagram of the entire device (on a huge sheet), with lists and other ESKD attributes.

  Symbols on electrical diagrams according to GOST: alphabetic, graphic

• album of schemes A4 c large quantity sheets (sometimes 100 or more sheets)

The first type is typical for the Soviet period and enterprises that work in the old fashioned way. Such a scheme is not convenient in all respects. The main thing is to find a large plane on which it can be decomposed. After a while, it will become completely unusable, and it is quite difficult to make a copy of it. It is not possible to clearly represent the device in such a diagram. The persistence of some large enterprises that continue to produce such schemes is surprising. The second type is more modern and actively applicable, especially in imported equipment. The inconvenience of these schemes is that you are tormented by flipping through such a scheme. Moreover, most simply draw each element of the circuit separately on a separate sheet, and the connection of elements is shown with links to sheets and signals. More advanced manufacturers depict at least a safety chain on separate sheets. industrial equipment.

Therefore, if you have received a new machine, then I advise you to immediately draw a blocking diagram of the machine with all the elements, this will significantly reduce the time to bring the equipment out of a stupor. There are very few schemes in which the balance of small and large (important and not important) is observed, the manufacturer does not bother with this.

§3 Rules for drawing up circuit diagrams.

Basic rules for drawing up schematic diagrams:
• Break the device into functional parts:
  • nutrition
  • blocking chain
  • final input devices and signal passing to the decision device
  • final output devices and signals to them from the decision device
  • solver
  • communication with other equipment
• It's good if you can depict these parts on separate sheets.
• The movement of circuit signals is always! should be left to right. That is, the input end devices should be on the left side of the diagram, and the output end devices on the right side of the diagram. (This also applies to each individual element)
• The supply current in circuit diagrams must flow from top to bottom! That is, the top of the circuit corresponds to a greater voltage potential. (This also applies to each individual element)
• Do not overload the circuit with connecting wires, the main goal is to show the path of input information signals in their movement to the decision device (or from the decision device to the final final devices). Not the main signals for this part, it is desirable to designate links.
• You can not display some of the elements of the scheme to improve readability, placing less significant elements on separate sheets.

Fig1. AON circuit diagram (Input / output part)

Here, for example, is a part of the AON circuit, it shows the input and output signals and their paths. The microprocessor part of the device is not specifically shown here, it is placed on a separate sheet. And the signals from the microprocessor part are shown from the bus. The common bus of this circuit and the microprocessor part are considered connected, although this somewhat contradicts the ESKD, but everything is immediately clear what goes where and how.

§4. Graphic representation of connections.

In the circuit diagrams of different industries, there are differences in the image of individual elements. There are traditions in the image of the elements of circuit diagrams.

We can distinguish the following traditional schemes:
• analog and digital devices
• schemes of industrial equipment
• power supply and lighting schemes

The following description is based on diagrams for analog and digital devices. We will consider power supply schemes and industrial equipment separately.

4.1 Connecting lines.

Each bus wire must have its own name. All wires in a bus with the same name are considered one wire.

4.2 Connection with common wires.

All signals with the same image and caption are considered to be connected. Use these signs to make graphic representation easier. At the same time, for power wires, follow the rule: "current must flow from top to bottom"

4.3 Special designations of connections.

Special designations are used to clarify the properties of compounds.

§5. Designation of elements on circuit diagrams.

Each element of the circuit diagram is indicated by an alphanumeric code. There are many designation options, here I will give the most common one, which corresponds to GOST 2.710-81 (ST SEV 6300-88)

Rules for designating elements on the diagram:
• The designation of the element is applied above its image, although it is permissible to apply the designation to the right of the element, or in general where there is free space;
• The denomination of the element is applied below the image of the element, or, if possible, under the name of the element.
• Identical elements are signed with the same letter code, but each element has its own individual serial number
• The numbering of identical elements in the circuit goes in the order from top to bottom and from left to right.

Usually, the full value of the element is indicated in the list attached to the circuit diagram, but GOST 2.702-75 allows a simplified application of the element's value to the circuit diagram:

for resistors:
• from 0 to 999 Ohm - without indication of units of measurement,
• from 1 * 10 ^ 3 to 999 * 10 ^ 3 Ohm - in kilo-ohms with the designation of the lowercase letter k,
• from 1 * 10 ^ 6 to 999 * 10 ^ 6 Ohm - in megaohms with the designation of the capital letter M,
• over 1 * 10 ^ 9 Ohm - in gigaohms with the designation with a capital letter G;

for capacitors:
• from 0 to 9999 * 10^-12 F - in picofarads without indicating the unit of measurement,
• from 1*10^-8 to 9999*10^-6 F - in microfarads with the designation lower case mk.

But the established practice of designating the ratings of capacitors is as follows:
• denomination without a comma - picofarads (100 - one hundred picofarads)
• denomination with a comma - microfarads (0.1 - 0.1 microfarads)

In some circuits, this is also used for resistors (but this is not correct)

To designate the type of element, the coding is used in Latin uppercase letters.

The first letter of the element is mandatory and defines the element type, the second letter breaks the element type into some subset.

A - device (general designation)

B- converters of non-electrical quantities into electrical ones (except for generators and power supplies) or vice versa analog or multi-digit converters or sensors for indicating or measuring
• BA- Loudspeaker
• BB- Magnetostrictive element
• BC- selsyn sensor
• BD- Detector of ionizing radiation
• BE- Selsyn receiver
• BF- Telephone (capsule)
• BK- Thermal sensor
• BL- Photocell
• BM-Microphone
• BP- pressure sensor
• BQ- Piezo element
• BR- Speed ​​sensor (tachogenerator)
• BS-Pickup
• BV- Speed ​​sensor

D- Integrated circuits, microassemblies
• DA- Analog integrated circuit
• DD- Integrated circuit, digital, logic element
• DS - Storage Devices
• DT - Delay Device

E- Elements are different
• EK- Heating element
• EL- Lighting lamp
• ET- Igniter

F- Surge arresters, fuses, protective devices
• FA - Discrete instantaneous current protection element
• FP- Discrete current protection element of inertial action
• FU- fuse fuse
• FV- Discrete voltage protection element, surge arrester

G- Generators, power supplies
• GB-Battery

H- Indicating and signaling devices
• HA - Sound alarm device
• HG- symbolic indicator
• HL- Light signaling device

K- Relays, contactors, starters
• KA- current relay
• KH-Indicative relay
• KK- Electrothermal relay
• KM- Contactor, magnetic starter
• KT - Time relay
• KV- Voltage relay

L-Inductors, chokes
• LL- Fluorescent lighting choke

P- Devices, measuring equipment. Note. The PE combination is not allowed.
• PA- Ammeter
• PC- Pulse Counter
• PF-Frequency meter
• PI- Active energy meter
• PK- Reactive Energy Meter
• PR- Ohmmeter
• PS- Recording device
• PT- Clock, action time meter
• PV- Voltmeter
• PW- Wattmeter

Q- Switches and disconnectors in power circuits (power supply, equipment power supply, etc.)
• QF- Circuit breaker
• QK- short circuit
• QS-Disconnector

R- Resistors
• RK- Thermistor
• RP-Potentiometer
• RS- measuring shunt
• EN- Varistor

S- Switching devices in control, signaling and measuring circuits. Note. The designation SF is used for devices that do not have power circuit contacts.
• SA- switch or switch
• SB- pushbutton switch
• SF- Circuit breaker
• SL - Level switches
• SP - Pressure switches
• SQ- Position switches (travel)
• SR - Switches triggered by speed
• SK - temperature switches

T- Transformers, autotransformers
• TA- Current transformer
• TS- Electromagnetic Stabilizer
• TV- voltage transformer

U- Communication devices.

Electrical to electrical converters

• UB-Modulator
• UR- Demodulator
• UI-Discriminator
• UZ- Frequency converter, inverter, frequency generator, rectifier

V- Electrovacuum and semiconductor devices
• VD- Diode, zener diode
• VL- Electrovacuum device
• VT- Transistor
• VS- Thyristor

W - Microwave lines and elements. Antennas
• WE- Coupler
• WK- short circuit
• WS-valve
• WT- Transformer, heterogeneity, phase shifter
• WU- Attenuator
• WA- Antenna

X- Contact connections
• XA- Current collector, sliding contact
• XS-Socket
• XT-Removable connection
• XW- high frequency connector

Y- Mechanical devices with electromagnetic drive
• YA- Electromagnet
• YB- Brake with electromagnetic drive
• YC-Coupling with electromagnetic drive
• YH- Electromagnetic chuck or plate

Z- Devices terminal filters. Limiters
• ZL-Limiter
• ZQ- Quartz filter

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What are the electrical symbols on the diagrams

Wiring diagram of the apartment

The wiring diagram in the apartment is a document that indicates the location electrical wires and electrical installation devices (electrical sockets, switches, lamps), electrical panel with
metering devices, power distribution, as well as with protective devices.

Knowledge of the wiring diagram is necessary as in the case of electrical work- troubleshooting in electrical wiring or upgrading the circuit, as well as in the case of simple construction actions such as drilling or hammering a nail, as this can damage the wires and leave the apartment without electricity, and get an electric shock yourself.

Symbols on the wiring diagram

In order for you to set a task for electricians, you will have to learn the simple language of electrical circuits, if you do not know the decoding of symbols, then electricians simply will not understand you.

General rules for the location of electrical wiring in the apartment

The power supply scheme of an apartment, with all the variety of house projects and apartment layouts, have common points that allow you to deal with the power supply scheme of a particular apartment.

• The power supply of the apartment begins with an electrical panel, which is located or inside the apartment at front door, or on the stairwell
• There are several circuit breakers in the electrical panel, each of which protects a separate power supply line
• Wire connections inside the apartment are made either in sockets or in junction boxes
• Mounting boxes are usually located above the switches at a distance of about 15-20 cm from the ceiling
• It is highly not recommended to drill walls at a distance of 15-20 cm from the ceiling, above sockets and switches - there is a high probability of interrupting the electrical wire
• If you need to find wiring boxes that were hidden and forgotten during renovations, the easiest way is to interview the neighbors living directly below and above your apartment.