To understand what exactly is shown on a diagram or drawing, you need to know the decoding of the icons that are on it. This recognition is also called blueprint reading. And to make this task easier, almost all elements have their own symbols. 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 symbols in electrical diagrams is in the regulatory documents.
Legend in electrical circuits: lamps, transformers, measuring instruments, basic components
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 make it easier to recognize these elements, uniform symbols have been introduced in electrical circuits. All rules are prescribed in GOSTs. There are many of these standards, but the main information is in the following standards:
Studying GOSTs is useful, but it requires time, which not everyone has enough of. Therefore, in the article we will present symbols in electrical circuits - the basic element base for creating drawings and wiring diagrams, circuit diagrams of devices.
Some experts, after carefully looking at the diagram, can say what it is and how it works. Some can even immediately issue possible problems that may arise during operation. It’s simple - they know the circuit design and element base well, and are also well versed in the symbols of circuit elements. This skill takes years to develop, but for dummies, it’s important to remember the most common ones first.
Electrical panels, cabinets, boxes
On the electrical supply diagrams of a house or apartment there will definitely be a symbol or 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 there is a route from it to illuminate other buildings located at some distance from the house - a bathhouse, a guest house. These other symbols are in the next picture.
If we talk about images of the “filling” 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 (the table has two pages, scroll by clicking on the word “Next”)
| Number | Name | Image on the diagram |
|---|---|---|
| 1 | Circuit breaker (automatic) |  |
| 2 | Switch (load switch) |  |
| 3 | Thermal relay (overheat protection) |  |
| 4 | RCD (residual current device) |  |
| 5 | Differential automatic (difavtomat) |  |
| 6 | Fuse | |
| 7 | Switch (switch) with fuse |  |
| 8 | Circuit breaker with built-in thermal relay (for motor protection) |  |
| 9 | Current transformer |  |
| 10 | Voltage transformer |  |
| 11 | Electricity meter |  |
| 12 | A frequency converter |  |
| 13 | Button with automatic opening of contacts after pressing |  |
| 14 | Button with contact opening when pressed again |  |
| 15 | A button with a special switch to turn off (stop, for example) |  |
Element base for electrical wiring diagrams
When drawing up or reading a diagram, the designations of wires, terminals, grounding, zero, etc. are also useful. This is what a novice electrician simply needs, or in order to understand what is shown in the drawing and in what sequence its elements are connected.
| Number | Name | Designation electrical elements on the diagrams |
|---|---|---|
| 1 | Phase conductor |  |
| 2 | Neutral (zero working) N |  |
| 3 | Protective conductor (ground) PE |  |
| 4 | Combined protective and neutral conductors PEN |  |
| 5 | Electrical communication line, buses |  |
| 6 | Bus (if it needs to be allocated) |  |
| 7 | Busbar taps (made by soldering) |  |
An example of the use of the above graphic images is in the following diagram. Thanks to the letter designations, everything is clear even without graphics, but duplication of information in diagrams has never been superfluous.
Picture of sockets
The wiring diagram should indicate the installation locations of sockets and switches. There are many types of sockets - 220 V, 380 V, hidden and open type installations, with different amounts“seating” places, waterproof, etc. To give a designation for each is too long and unnecessary. 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 is 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 body (illustration in the photo below). If only one plug can be plugged into the socket, one segment is drawn upward, if two, two, etc.
If you look at the images closely, notice that the symbolic image that is on the right does not have a horizontal line that separates the two parts of the icon. This line indicates that the socket is concealed, that is, it is necessary to make a hole in the wall for it, install a socket box, etc. The option on the right is for open mounting. A non-conductive substrate is attached to the wall, and the socket itself is on it.
Also note that Bottom part the left schematic image is crossed out by a vertical line. This indicates the presence of a protective contact to which grounding is connected. Installation of sockets with grounding is mandatory when turning on a complex household appliances such as a washing machine, oven, etc.
The symbol of a three-phase outlet (380 V) cannot be confused with anything. The number of segments sticking up is equal to the number of conductors that this device connected - three phases, zero and ground. Total five.
It happens that the lower part of the image is painted black (dark). This means that the outlet is waterproof. These are placed outdoors, in rooms with high humidity(baths, swimming pools, etc.).
Switch Display
The schematic designation of the switches looks like small size a circle with one or more L- or T-shaped branches. Taps in the shape of the letter “G” indicate an open-mounted circuit breaker, while those in the shape of the letter “T” indicate a flush-mounted switch. 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. To the same small circle with opposite sides draw two letters “G”. This is how a single-key pass-through switch is designated.
Unlike conventional switches, in these, when using two-key models, another bar is added, parallel to the top one.
Lamps and fixtures
Lamps have their own designations. Moreover, there is a difference between fluorescent lamps and incandescent lamps. The diagrams even show the shape and dimensions of the lamps. In this case, you just need to remember what each type of lamp looks like on the diagram.
Radioelements
When reading circuit diagrams of devices, you need to know the symbols of diodes, resistors, and other similar elements.
Knowledge of conventional graphic elements will help you read almost any diagram - any device or electrical wiring. The values of the required parts are sometimes indicated next to the image, but in large multi-element circuits they are written in a separate table. It contains letter designations of circuit elements and denominations.
Letter designations
In addition to the fact that the elements on the diagrams have conventional graphic names, they have letter designations, which are also standardized (GOST 7624-55).
| Electrical circuit element name | Letter designation | |
|---|---|---|
| 1 | Switch, controller, switch | IN |
| 2 | Electric generator | G |
| 3 | Diode | D |
| 4 | Rectifier | VP |
| 5 | Sound alarm (bell, siren) | Sv |
| 6 | Button | Kn |
| 7 | Incandescent lamp | L |
| 8 | Electrical engine | M |
| 9 | Fuse | Etc |
| 10 | Contactor, magnetic starter | TO |
| 11 | Relay | R |
| 12 | Transformer (autotransformer) | Tr |
| 13 | Plug connector | Sh |
| 14 | Electromagnet | Em |
| 15 | Resistor | R |
| 16 | Capacitor | WITH |
| 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 (voltaic 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 designated by Latin letters.
There is one subtlety in the designation of the relay. They are different types, are marked accordingly:
- current relay - RT;
- power - RM;
- voltage - RN;
- 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 you can now understand most of the drawings and plans. If you need to know images of rarer elements, study GOST standards.
The ability to read electrical diagrams is an important component, without which it is impossible to become a specialist in the field electrical installation work. Every novice electrician must know how sockets, switches, switching devices and even an electricity meter are designated on a wiring project in accordance with GOST. Next, we will provide readers of the site with symbols in electrical circuits, both graphic and alphabetic.
Graphic
As for the graphic designation of all elements used in the diagram, we will provide this overview in the form of tables in which the products will be grouped by purpose.
In the first table you can see how electrical boxes, panels, cabinets and consoles are marked on electrical circuits:
The next thing you should know is the symbol for power sockets and switches (including walk-through ones) on single-line diagrams of apartments and private houses:
As for lighting elements, lamps and fixtures according to GOST are indicated as follows:
In more complex schemes where electric motors are used, elements such as:
It is also useful to know how transformers and chokes are graphically indicated on circuit diagrams:
Electrical measuring instruments according to GOST have the following graphic designation on the drawings:
By the way, here is a table useful for novice electricians, which shows what the ground loop looks like on a wiring plan, as well as the power line itself:
In addition, in the diagrams you can see a wavy or straight line, “+” and “-”, which indicate the type of current, voltage and pulse shape:
In more complex automation schemes you may encounter incomprehensible graphic symbols, like contact connections. Remember how these devices are designated on electrical diagrams:
In addition, you should be aware of what radio elements look like on projects (diodes, resistors, transistors, etc.):
That's all the conventional graphic symbols in the electrical circuits of power circuits and lighting. As you have already seen for yourself, there are quite a lot of components and remembering how each is designated is possible only with experience. Therefore, we recommend that you save all these tables so that when reading the wiring plan for a house or apartment, you can immediately determine what kind of circuit element is located in a certain place.
Interesting video
Reading diagrams is impossible without knowledge of the conventional graphic and letter designations of the elements. Most of them are standardized and described in regulatory documents. Most of them were published in the last century, and only one new standard 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 “as who came up with it.” And this is the difficulty of reading circuit diagrams of new devices. But, basically, the symbols in electrical circuits are described and are well known to many.
Two types of symbols are often used on diagrams: graphic and alphabetic, and denominations are also often indicated. From this data, many can immediately tell how the scheme works. This skill is developed over years of practice, and first you need to understand and remember the symbols in electrical circuits. Then, knowing the operation of each element, you can imagine the final result of the device.
For composing and reading various schemes usually required different elements. There are many types of circuits, but in electrical engineering the following are usually used:
There are many other types of electrical circuits, but they are not used in home practice. The exception is the route of cables passing through the site and the supply of electricity to the house. This type of document will definitely be needed and useful, but it is more of a plan than an outline.
Basic images and functional features
Switching devices (switches, contactors, etc.) are built on contacts of various mechanics. There are make, break and switch contacts. The normally open contact is open; when it is switched to operating state, the circuit is closed. The break contact is normally closed, but under certain conditions it operates, breaking the circuit.
The switching contact can be two or three position. In the first case, first one circuit works, then another. The second one 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 are performed only by moving contacts. They are shown in the photo below.
Basic functions can only be performed by fixed contacts.
Symbols for single line diagrams
As has already been said, single-line diagrams indicate only the power part: RCDs, automatic devices, automatic circuit breakers, sockets, circuit breakers, switches, etc. and connections between them. The designations of these conventional 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 small detail. For example, a machine (circuit breaker) and a 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 switch designation is the shape of the icon on the fixed contact. It's a very small difference, but the device and its functions are different. You need to look closely at all these little things and remember them.
There is also a small difference between the symbols of the RCD and the differential circuit breaker. It also only functions as moving and fixed contacts.
The situation is approximately the same with relay and contactor coils. They look like a rectangle with small graphic additions.
In this case, it’s easier to remember, since there are quite serious differences in appearance additional icons. With a photo relay it’s so simple - the rays of the sun are associated with the arrows. A pulse 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-in connection(such as a socket/plug or socket/plug) looks like two brackets, and a collapsible one (such as a terminal block) looks like circles. Moreover, the number of pairs of checkmarks or circles indicates the number of wires.
Picture of buses and wires
In any circuit there are connections and for the most part they are made by wires. Some connections are buses - more powerful conductor elements from which taps can extend. Wires are indicated by a thin line, and branches/connections are indicated by dots. If there are no points, it is not a connection, but an intersection (without an electrical connection).
There are separate images for buses, but they are used if they need to be graphically separated from communication lines, wires and cables.
On wiring diagrams it is often necessary to indicate not only how the cable or wire runs, but also its characteristics or installation method. All this is also displayed graphically. This is also necessary information for reading drawings.
How switches, switches, sockets are depicted
There are no standards-approved images for some types of this equipment. So, dimmers (light regulators) and push-button switches remained without designation.
But all other types of switches have their own symbols in electrical diagrams. They come in open and hidden installations, respectively, there are also two groups of icons. The difference is the position of the line on the key image. To understand in the diagram what type of switch it is we're talking about, this must be remembered.
There are separate designations for two-key and three-key switches. In the documentation they are called “twin” and “twin”, respectively. There are differences for cases with different degrees of protection. Into premises with normal conditions For operation, switches are installed with IP20, maybe up to IP23. In wet rooms (bathroom, swimming pool) or outdoors, the degree of protection should be at least IP44. Their images differ in that the circles are filled in. So it's easy to distinguish them.
There are separate images for the switches. These are switches that allow you to control turning the light on/off 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, and 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 a housing of increased protection (IP44 and higher), the middle is tinted dark.
Symbols in electrical diagrams: sockets of different types of installation (open, hidden)
Having understood the logic of the designation and remembering some initial data (what is the difference between the symbolic image of an open and hidden installation socket, for example), after a while you will be able to confidently navigate the drawings and diagrams.
Lamps on diagrams
This section describes the symbols in the electrical circuits of various lamps and fixtures. Here the situation with the designations of the new element base is better: there are even signs for LED lamps and lamps, compact fluorescent lamps (housekeepers). It’s also good that the images of lamps of different types differ significantly - it’s difficult to confuse them. 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 fluorescent lamp and an LED lamp 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 pendant 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 electrical circuit diagrams
Schematic diagrams of devices contain a different element base. Communication lines, terminals, connectors, light bulbs are also depicted, but in addition there is a large number of radioelements: resistors, capacitors, fuses, diodes, thyristors, LEDs. Most of the symbols in the electrical circuits of this element base are shown in the figures below.
Rarer ones will have to be looked for separately. But most circuits contain these elements.
Letter symbols in electrical diagrams
In addition to graphic images, elements on the diagrams are labeled. It also helps to read the diagrams. Near letter designation an element is often identified by its serial number. This is done so that later it is 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. Excerpts from there with the table below.
STATE STANDARDS
Unified system of design documentation
CONVENTIONAL SYMBOLS
GRAPHICAL IN ELECTRICAL DIAGRAMS
SWITCHING DEVICES
AND CONTACT CONNECTIONS
GOST 2.755-87
(CT SEV 5720-86)
IPC PUBLISHING HOUSE OF STANDARDS
Moscow 1998
STATE STANDARD OF THE USSR UNION
|
Unified system of design documentation CONVENTIONAL GRAPHIC NOTATIONS SWITCHING DEVICES Unified system for design documentation. Graphic designs in diagrams. Commutational devices and contact connections |
GOST (CT SEV 5720-86) |
Date of introduction 01.01.88
This standard applies to manual or automated diagrams of products from all branches of industry and construction and establishes conventional graphic symbols for switching devices, contacts and their elements. This standard does not establish conventional graphic symbols on railway signaling, centralization and interlocking diagrams. Conventional graphic symbols of mechanical connections, drives and devices - according to GOST 2.721. Conventional graphic designations of the receiving parts of electromechanical devices - according to GOST 2.756. The dimensions of individual graphic symbols and the ratio of their elements are given in the Appendix. 1. General rules for constructing contact designations. 1.1. Switching devices on the diagrams should be shown in the position taken as the initial one, in which the starting contact system is de-energized. 1.2. Contacts of switching devices consist of moving and fixed contact parts. 1.3. To depict the main (basic) functional features of switching devices, conventional graphic designations of contacts are used, which can be made in a mirror image: 1) making contacts 2) breaking contacts 3) switching contacts 4) switching contacts with a neutral central position 1.4. To explain the principle of operation of switching devices, if necessary, the qualifying symbols shown in Table 1 are displayed on their contact parts. 1.
Table 1
|
Name |
Designation |
| 1. Contactor function | |
| 2. Switch function | |
| 3.Disconnector function | |
| 4. Switch-disconnector function | |
| 5. Automatic triggering | |
| 6. Travel or limit switch function | |
| 7. Self-return | |
| 8. No self-return | |
| 9. Arc suppression | |
| Note. The designations given in paragraphs. 1 - 4, 7 - 9 of this table are placed on fixed contact parts, and the designations in paragraphs. 5 and 6 - on moving contact parts. | |
table 2
|
Name |
Designation |
| 1. Switching device contact: | |
| 1) switching without breaking the circuit (bridge) | |
| 2) with double circuit | |
| 3) with double opening | |
| 2. Pulse closing contact: | |
| 1) when triggered | |
| 2) upon return | |
| 3. Pulse normally open contact: | |
| 1) when triggered | |
| 2) upon return | |
| 3) when triggered and returned | |
| 4. Contact in contact group, which fires earlier in relation to other contacts in the group: | |
| 1) closing | |
| 2) opening | |
| 5. A contact in a contact group that triggers later in relation to other contacts in the group: | |
| 1) closing | |
| 2) opening | |
| 6. Contact without self-return: | |
| 1) closing | |
| 2) opening | |
| 7. Self-return contact: | |
| 1) closing | |
| 2) opening | |
| 8. Switching contact with a neutral central position, with self-return from the left position and without return from the right position | |
| 9. Contactor contact: | |
| 1) closing | |
| 2) opening | |
| 3) closing arc extinguishing | |
| 4) breaking arc extinguishing | |
| 5) closing with automatic operation | |
| 10. Switch contact | |
| 11. Disconnector contact | |
| 12. Switch-disconnector contact | |
| 13. Limit switch contact: | |
| 1) closing | |
| 2) opening | |
| 14. Temperature sensitive contact (thermal contact): | |
| 1) closing | |
| 2) opening | |
| 15. Normally closed contact with delay operating: | |
| 1) when triggered |
|
| 2) upon return |
|
| 3) when triggered and returned |
|
| 16. Normally closed contact with delay operating: | |
| 1) when triggered |
|
| 2) upon return |
|
| 3) when triggered and returned |
|
| Note to paragraphs. 15 and 16. Deceleration occurs when moving in the direction from the arc to its center. |
Table 3
|
Name |
Designation |
|
| 1. Switch closing contact: | ||
| 1) single pole | ||
|
Single line |
Multiline |
|
| 2) three-pole |
|
|
| 2. Closing contact of a three-pole switch with automatic operation of the maximum current |
|
|
| 3. Closing contact of a push-button switch without self-return, with opening and return of the control element: | ||
| 1) automatically | ||
| 2) by pressing the button a second time | ||
| 3) by pulling the button | ||
| 4) via a separate drive (example of pressing a reset button) | ||
| 4. Three-pole disconnector | ||
| 5. Three-pole switch-disconnector | ||
| 6. Manual switch |
|
|
| 7. Electromagnetic switch (relay) |
|
|
| 8. Limit switch with two separate circuits | ||
| 9. Thermal self-regulating switch Note. A distinction should be made in the representation of the contact and the thermal relay contact, depicted as follows | ||
| 10. Inertia switch | ||
| 11. Three-point mercury switch | ||
Table 4
|
Name |
Designation |
| 1. Single-pole multi-position switch (six-position example) |
|
| Note. Switch positions in which there are no switched circuits, or positions connected to each other, are indicated by short strokes (an example of a six-position switch that does not switch an electrical circuit in the first position and switches the same circuit in the fourth and sixth positions) |
|
| 2. Single pole, six position transfer switch |
|
| 3. Single-pole, multi-position switch with a moving contact that closes three adjacent circuits in each position |
|
| 4. Single-pole, multi-position switch with a moving contact that closes three circuits, excluding one intermediate |
|
| 5. Single-pole, multi-position switch with a moving contact, which in each subsequent position connects a parallel circuit to the circuits closed in the previous position |
|
| 6. Single-pole, six-position switch with a moving contact that does not open the circuit when moving from the third to the fourth position |
|
| 7. Two-pole, four-position switch |
|
| 8. A two-pole, six-position switch in which the third contact of the upper pole operates earlier, and the fifth contact later, than the corresponding contacts of the lower pole. |
|
| 9. Multi-position switch of independent circuits (example of six circuits) | |
| Notes to paragraphs. 19: | |
| 1. If it is necessary to indicate the limitation of movement of the switch drive, use a position diagram, for example: | |
| 1) the drive ensures the transition of the moving contact of the switch from position 1 to position 4 and back |
|
| 2) the drive ensures the transition of the moving contact from position 1 to position 4 and then to position 1; reverse movement is only possible from position 3 to position 1 |
|
| 2. The position diagram is connected to the moving contact of the switch by a mechanical connection line |
|
| 10. A switch with complex switching is shown in the diagram as one of following methods: 1) general designation (example designation of an eighteen-position rotary switch with six terminals, designated A to F) |
|
| 2) designation according to design |
|
| 11. Switch two-pole, three-position with neutral position | |
| 12. Two-pole, three-position switch with self-return to neutral position |
Table 5
|
Name |
Designation |
| 1. Pin connection contact: | |
| 1) detachable connection: | |
| - pin |
|
| - nest |
|
| 2) collapsible connection |
|
| 3) permanent connection |
|
| 2. Sliding contact: | |
| 1) along a linear conductive surface | |
| 2) along several linear conductive surfaces | |
| 3) along an annular conductive surface | |
| 4) along several annular conductive surfaces Note. When making diagrams using a computer, it is allowed to use shading instead of blackening |
Table 6
|
Name |
Designation |
| 1. Detachable contact connection |
|
| 2. Four-wire detachable contact connection |
|
| 3. Four-wire connector pin |
|
| 4. Four-wire connector socket |
|
| Note. In paragraphs 2 - 4 digits inside rectangles indicate contact numbers | |
| 5. Detachable coaxial contact connection |
|
| 6. Contact jumpers | |
| Note. Type of connection, see table. 5, paragraph 1. | |
| 7. Terminal block Note: To indicate the types of contact connections, the following designations may be used: |
|
| 1) pads with removable contacts | |
| 2) pads with detachable and non-separable contacts | |
| 8. Switching jumper: | |
| 1) to open |
|
| 2) with the pin removed | |
| 3) with the socket removed | |
| 4) to switch | |
| 9. Connection with protective contact |
|
Table 7
|
Name |
Designation |
| 1. Finder brush with circuit breaker when switching |
|
| 2. Finder brush without breaking the circuit when switching |
|
| 3. Finder field contact (output) | |
| 4. Group of contacts (outputs) of the finder field |
|
| 5. Contact finder field |
|
| 6. Finder field contact with initial position Note. The initial position designation is used if necessary | |
| 7. Contact finder field with images of contacts (outputs) |
|
| 8. Finder field showing groups of contacts (outputs) |
|
Table 8
|
Name |
Designation |
| 1. One-move finder without brushes returning to their original position | |
| 2. One-motion finder with brushes returning to their original position. | |
| Note. When using a finder in a four-wire path, the designation of a finder with the brushes returning to their original position is used |
Any electrical circuits can be presented in the form of drawings (circuit and installation diagrams), the design of which must comply with ESKD standards. These standards apply to both electrical wiring or power circuits and electronic devices. Accordingly, in order to “read” such documents, it is necessary to understand the symbols in electrical circuits.
Regulations
Taking into account the large number of electrical elements, a number of normative documents have been developed for their alphanumeric (hereinafter referred to as BO) and conventional graphic designations (UGO) to eliminate discrepancies. Below is a table showing the main standards.
Table 1. Graphic designation standards individual elements in installation and circuit diagrams.
| GOST number | Short description |
| 2.710 81 | This document contains GOST requirements for BO various types electrical elements, including electrical appliances. |
| 2.747 68 | Requirements for the dimensions of displaying elements in graphical form. |
| 21.614 88 | Accepted codes for electrical and wiring plans. |
| 2.755 87 | Display of switching devices and contact connections on diagrams |
| 2.756 76 | Standards for sensing parts of electromechanical equipment. |
| 2.709 89 | This standard regulates the standards in accordance with which diagrams indicate contact connections and wires. |
| 21.404 85 | Schematic symbols for equipment used in automation systems |
It should be taken into account 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 automatic devices have been widely used in Russia for more than a decade, but uniform standard according to GOST 2.755-87 standards there are still no requirements for these devices, unlike circuit breakers. It is quite possible that this issue will be resolved in the near future. To keep abreast of such innovations, professionals monitor changes in regulatory documents; amateurs do not have to do this; it is enough to know the decoding of the main symbols.
Types of electrical circuits
In accordance with ESKD standards, diagrams mean graphic documents on which, using accepted notations, the main elements or components of a structure, as well as the connections connecting them, are displayed. According to the accepted classification, there are ten types of circuits, of which three are most often used in electrical engineering:
If the diagram shows only the power part of the installation, then it is called single-line; if all elements are shown, then it is called complete.
If the drawing shows the wiring of the apartment, then the locations lighting fixtures, sockets and other equipment are indicated on the plan. Sometimes you can hear such a document called a power supply diagram; this is incorrect, since the latter shows how consumers are connected to a substation or other power source.
Having dealt with the electrical circuits, we can move on to the designations of the elements indicated on them.
Graphic symbols
Each type of graphic document has its own designations, regulated by relevant regulatory documents. Let us give as an example the basic graphic symbols for different types electrical diagrams.
Examples of UGO 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 – Basic (1) and acceptable (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 remote control or electrical panel.
- C – Display of actuators (AM).
- D – Influence of MI on the regulating body (hereinafter referred to as RO) when the power is turned off:
- RO opening occurs
- Closing RO
- The position of the RO remains unchanged.
- E - IM, on which is additionally installed manual drive. This symbol may be used for any RO provisions specified in paragraph D.
- F- Accepted mappings of communication lines:
- General.
- There is no connection at the intersection.
- The presence of a connection at the intersection.
UGO in single-line and complete electrical circuits
There are several groups of symbols for these schemes; we present the most common of them. To obtain complete information, please refer to the regulatory documents, numbers state standards will be given for each group.
Power supplies.
To designate them, the symbols shown in the figure below are used.
UGO power supplies on schematic diagrams (GOST 2.742-68 and GOST 2.750.68) Description of symbols:
- A is a constant voltage source, its polarity is indicated by the symbols “+” and “-”.
- B – electricity icon indicating alternating voltage.
- C is a symbol of alternating and direct voltage, used in cases where the device can be powered from any of these sources.
- D – Display of battery or galvanic power supply.
- E- Symbol of a battery consisting of several batteries.
Communication lines
The basic elements of electrical connectors are presented 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 types electrical connections.
- B – Current-carrying or grounding bus.
- C – Designation of shielding, can be electrostatic (marked with the symbol “E”) or electromagnetic (“M”).
- D - Grounding symbol.
- E – Electrical connection with the device body.
- F – On complex circuits, from several components, thus indicating a broken connection, 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 – Joint at 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.
UGO adopted for electromechanical devices and contactors (GOSTs 2.756-76, 2.755-74, 2.755-87) Description of symbols:
- A – symbol of the coil of an electromechanical device (relay, magnetic starter, etc.).
- B – UGO of the receiving part of the electrothermal protection.
- C – display of the coil of a device with mechanical interlock.
- D – contacts of switching devices:
- Closing.
- Disconnecting.
- Switching.
- E – Symbol for designating manual switches (buttons).
- F – Group switch (switch).
UGO of electric machines
Here are a few examples of displays electric machines(hereinafter referred to as EM) in accordance with the current standard.
Designation of electric motors and generators on circuit diagrams (GOST 2.722-68) Description of symbols:
- A – three-phase EM:
- Asynchronous (squirrel-cage rotor).
- Same as point 1, only in a two-speed version.
- Asynchronous electric motors with phase-phase rotor design.
- Synchronous motors and generators.
- B – Collector, DC powered:
- EM with permanent magnet excitation.
- EM with excitation coil.
UGO transformers and chokes
Examples of graphic symbols for these devices can be found in the figure below.
Correct designations of transformers, inductors and chokes (GOST 2.723-78) Description of symbols:
- A – This graphic symbol can indicate inductors or windings of transformers.
- B – Choke, which has a ferrimagnetic core (magnetic core).
- 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 viewing GOSTs 2.729 68 and 2.730 73.
Examples of symbolic graphic symbols of electronic components and measuring instruments
Description of symbols:
- Electricity meter.
- Picture of an ammeter.
- Device for measuring network voltage.
- Thermal sensor.
- Fixed value resistor.
- Variable resistor.
- Capacitor (general designation).
- Electrolytic capacity.
- Diode designation.
- Light-emitting diode.
- Image of a diode optocoupler.
- UGO transistor (in this case npn).
- Fuse designation.
UGO lighting devices
Let's consider how to schematic diagram electric lamps are displayed.
Description of symbols:
- A – General image of incandescent lamps (LN).
- B - LN as a signaling device.
- C – Typical 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 electrical wiring diagram
Concluding the topic of graphic symbols, we give examples of displaying sockets and switches.
How sockets of other types are depicted is easy to find in the regulatory documents that are available on the Internet.
