What types of electrical circuits are there? How to read electrical diagrams. Types of electrical circuits Principle of operation of a circuit diagram

One of the required skills of a radio amateur, as well as any person directly involved in the repair or maintenance of electrical and electronic equipment, is the ability to read circuit diagrams. What is it?

This is a diagram in which each detail is indicated graphically, and after studying it, it becomes clear to us how they are all connected to each other. Circuit diagrams are the most important diagram as they allow us to understand how the device as a whole works. You will not find on the schematic diagrams images of the device itself, with terminals or pins to which the wires are soldered or clamped under a screw connection; wiring diagrams are used for this. The figure below shows the wiring diagram for connecting the electric meter:

As we know, from a school physics course, the connection in the diagram at the intersection of the wires is indicated by a bold dot.

The same intersection of wires without a point means that there is no connection in this place. There are a number of rules by which circuit diagrams are drawn up, for example, the input parts in a device are usually placed on the left side of the diagram, and the output parts on the right side. This can be seen in the example of a simple amplifier using a single transistor; parts of the input circuits are highlighted in red and the output circuits in green:

This designation, as in the figure below, denotes any DC power source. This can be either batteries or an AC power supply. A long line indicates the positive pole of the power source or plus, and a short line indicates a negative pole or minus.

This designation in the diagrams indicates a battery consisting of several galvanic elements (batteries) connected in series.

In the following figure we can see a designation that, depending on the circuit used, can mean either a button with or without fixation, a single-line toggle switch, or a key switch, or a contact of some device, such as a relay.

Relay contacts can be either freely closed or freely open. Let me explain that freely open contacts are contacts that are in an open state when there is no voltage on the relay coil. The figure below shows examples of freely open and freely closed contacts:

The following symbol denotes paired contacts that are mechanically connected to each other and are switched on or off simultaneously. These can be either relay contacts or switch or switch contacts:

As everyone knows, a diode has two terminals, a cathode and an anode, the diode designation can be seen in the figure below. The apex of the triangle, directed towards the dash, shows by its direction the direct connection of the diode when it conducts current, from anode to cathode, from plus to minus.

In bipolar transistors, which, as everyone knows, have three terminals - base, emitter, collector, the terminal with an arrow indicates the emitter, the base of the transistor is the base, and the remaining terminal, indicated simply by a dash, will be the collector.

Moreover, with the help of an arrow indicating the emitter and pointing inward or outward of the transistor, the structure of the transistor is indicated. This arrow symbolizes (as in a diode) a p-n junction, and is also directed from plus to minus or from positive to negative electrode.

Our transistor is, relatively speaking, two diodes connected to each other either by cathodes or anodes. Accordingly, if our base electrode is negative, then it will be a p-n-p structure transistor, and if it is positive, then it will be an n-p-n structure.

Thyristors have three electrodes, these are the cathode and anode, already familiar to us from the diode and having the same designation, plus a control electrode. Its designation can be seen in the figure below:

In our diagrams, capacitors are designated by two parallel strips, which imply 2 capacitor plates.

A polar electrolytic capacitor has a plus sign added to its designation, indicating the positive electrode of the capacitor, which must be connected strictly in accordance with the diagram.

Variable and tuning capacitors are designated like regular capacitors, but have a slash in their designation, indicating that they can change their capacitance. If this line ends with an arrow, then this is a variable capacitor designed when operating for multiple changes in the position of the plates or, in other words, for frequent changes in capacitance. If the slash ends with a cross line, then this is a tuning capacitor; such a capacitor is usually adjusted only once, when assembling the device.

In the figure above we can see the image of fixed resistor circuits. They have a constant resistance and two terminals. The variables have three terminals and allow you to adjust the resistance between the central and outer terminals, from zero to the nominal resistance of the resistor.

LEDs are indicated by a diode (sometimes with a circle, sometimes without one) with two arrows pointing away from the diode. Sometimes the diode is circled.

The figure below shows the designation of a transformer; in this case, the transformer is taken with several secondary windings:

The choke (coil with a core), as it is depicted in the diagrams, in the figure below under the number two, the image of the coil under the number one:

And the adjustable core coil is shown in Figure three. An image of connectors used in electrical engineering can be seen in the figure below; in this case, a block of connectors is shown, or in other words, several pieces paired with each other.

The following circuit diagram shows a relay:

Shown is a relay coil (left) and two groups of contacts that can operate as either make or break switches. The following shows a diode bridge as it is designated in the diagrams, and both images of the same bridge are used.

Here is the designation on the diagrams of a dynamic head, or, in other words, a regular speaker:

And here we can see the general designation of the microphone:

I am sure that now you can easily decipher the circuit diagram of any device yourself - TV, refrigerator, receiver, and so on. And to consolidate the material you have covered, try to decipher the cat’s diagram :)

Of course, this is only a small, although the main part of the symbols of the elements on the diagrams, but this is quite enough for you to get started. Lesson prepared - AKV.

Discuss the article BRIEF DIAGRAM

In this article we got acquainted with the three main types of circuits that are used in radio electronics and electrical engineering. Now let's look at each scheme in more detail.

1. Block diagram.

When they want to talk in general terms about any electrical device (device), then in the explanation they use a simplified version of the device diagram, composed only of the main functional parts (blocks) indicating their purpose and interconnections. This simplified scheme is called structural.

On structural diagram The main blocks of the device are depicted as rectangles, inside which the name of the block is written. Connections between blocks and the direction of the signal from one block to another are indicated by connecting lines with arrows. The blocks are arranged in accordance with the sequence of signal direction, and to make it as clear and readable as possible, they try to arrange them in one row from left to right.

For example, let's draw a structural diagram of a table lamp, but let's take its simplified version. That is, we will remove the housing and leave only the wire, plug, switch and socket with an incandescent lamp.

Now let's draw a block diagram of a simplified table lamp, where the first rectangle will conventionally represent a plug, the second a switch, the third an incandescent lamp.

The diagram in general terms gives an idea of ​​the structure of a table lamp, what functional blocks it consists of, the sequence of arrangement of the blocks and how they are connected to each other. What is inside the blocks is not indicated on the diagram, so as not to distract attention to unnecessary details that are not essential at the development or familiarization stage.

From the diagram it is clear that a table lamp requires three components: a plug, a switch and an incandescent lamp (LED, energy-saving), but it does not matter at all what these elements are. The main thing is to understand that the lamp consists of three interconnected elements and if at least one is missing, it will not work.

The circuit also determines that for the table lamp to operate, voltage is required, which is supplied to the incandescent lamp through the plug, wires and switch, i.e. reveals the principle of operation of a table lamp and the purpose of its individual blocks.

Sometimes inside a block its serial number is indicated followed by a description of the functionality or symbolic graphic symbols of elements are depicted that explain the general purpose of each block.

And yet it is impossible to make such a simple device as a table lamp using only a structural diagram. Too little information is given about each block, making it difficult to understand how they work. Therefore, in order to know and understand what elements the device consists of, how these elements interact with each other and how they are connected electrically, electrical circuit diagrams.

2. Electrical circuit diagram.

On schematic diagram the sequence and structure of the block diagram is preserved, but instead of general functional blocks, the full composition of the elements of the device (device) is shown, depicted in the form conventional graphic symbols. Each part is depicted with the number of pins that real parts have, and the connections between the pins are shown in such a way that you can trace all the circuits and connections in detail, and easily understand the processes taking place and the principle of operation of the device.

For ease of reading, the details are indicated next to the symbolic image. alphanumeric designation, which defines information about the part: functional purpose, location and marking in the diagram. Alphanumeric designations are indicated in abbreviated form and consist of a certain number of letters of the Latin alphabet and Arabic numerals, written sequentially, on one line and without spaces.

Letter designation taken from the part name and indicated by one or two first letters, for example, R– resistor, WITH– capacitor, V.D.– diode, VT– transistor, S.A.– switch, XP– two-pole plug, EL– lighting lamp, etc.

Digital designation indicates the serial number of parts of the same type in the diagram, for example, R1, R2, R3 etc., or VD10, VD11 etc.

Let's draw a schematic electrical diagram of a table lamp, and for ease of reading the diagram, at the first stage, we will highlight its main elements with green rectangles.

Looking at the diagram, we can say that to power the table lamp, an alternating voltage of 220 V is used, which is supplied through a plug XP1 and switch SA1 fed to the light bulb EL1. That all elements are designed for an operating alternating voltage of 220 V, and that the lamp is operated by the position of the switch contact SA1: when the contact is closed, the light bulb EL1 lights up, when opened, goes out.

From the diagram it can be seen that the upper terminal of the plug XP1 connected to the left terminal of the switch contact according to the diagram SA1, the right terminal of the switch contact is connected to the upper terminal of the light bulb EL1, and the lower terminal of the light bulb is connected to the lower terminal of the plug XP1. Switch contact SA1 shown in an open state, which corresponds to its initial position and the turned off state of the table lamp. The electrical connection between the terminals of the elements is depicted by segments of horizontal and vertical lines.

And at the same time, the circuit diagram does not give us a complete picture of the table lamp, since it does not indicate information about the design of the lamp and the dimensions of the parts. The fact is that when studying the principle of operation, there is no need to know how, for example, the light bulb is made (size and shape of the bulb, type and size of the base, coil resistance, etc.), what design the switch or plug has. If all this information were indicated on the diagram, they would only distract attention to unnecessary details that are not of fundamental importance.

But still, to expand the functionality, some part of the design data of the elements (power, type, method of connection) is indicated on the circuit diagrams, because in some cases it turns out to be the main and only document that is used to guide the manufacture, adjustment, maintenance and repair of equipment.

The considered structural and circuit diagrams are intended mainly for studying the principle of operation, and depending on the type, they provide a visual representation of the functional or elemental structure. To have an idea of ​​the design of a table lamp, the approximate arrangement of elements and methods of connection between them, use connection diagram or wiring diagram.

3. Connection diagram (wiring diagram).

Connection diagram or wiring diagram is created on the basis of a principle and is a simplified design drawing depicting the device in one or several projections. The diagram shows all the elements that make up the device, their actual location inside and outside the device, and all electrical connections between the elements. In some cases, a wiring diagram can be a clear photograph of the arrangement of elements indicating numerical and letter designations.

In the process of manufacturing complex electrical devices, some of the connections between individual large blocks, assemblies, elements or circuit boards are made with connecting wires, which are tied into bundles or passed inside shielding sleeves. And if you do not use a wiring diagram when repairing or servicing such equipment, then in some cases it is very difficult to trace the passage of a signal through individual wires that communicate between nodes and elements. Sometimes you even have to unsolder the wires from both ends of the harness and make them match.

On a wiring diagram, elements are depicted in the form of conventional graphic images or in the form of simplified contour drawings of real elements. Next to the symbols of the elements, their alphanumeric designations are indicated according to the circuit diagram. Wires and cables are shown in separate lines indicating the “addresses” of their external connections, and if necessary, indicate the brand, cross-section and color of the wires, characteristics and name of the external circuits (voltage, frequency, type of signal, etc.).

Let's take a look at the wiring diagram of a simplified table lamp. Switch SA1 and a light bulb EL1 are depicted as outline drawings, and the fork XP1 in the form of a graphic symbol.

From the above diagram it can be seen that the upper terminal of the plug is connected to the middle terminal of the switch, the right terminal of the switch is connected to the lower terminal of the light bulb. The side terminal of the light bulb, in contact with the base body, is connected to the lower terminal of the plug.

Of course, the given diagram of a table lamp is simple, and it is difficult to show all the aspects of constructing the wiring diagram, but still the very principle of construction is visible on it.

The main thing to understand here is that the wiring diagram repeats the schematic diagram in everything, and that all the parts on the wiring diagram are connected in the same way as on the schematic diagram. The only difference between the diagrams may be the location and connection of parts, which, when assembling a real device, may be spaced in different directions for reasons of simplifying installation or reducing the influence of one element on another.

So we looked at the three main types of circuits that you will encounter when designing, servicing or repairing amateur radio or electrical devices. And although this is not the entire list of schemes, since there are also functional, connections, are common, layout plans, but to understand the structure or operating principle of a radio-electronic or electrical device, the three considered are sufficient.

Literature:

1. GOST 2.701-2008 Unified system of design documentation. Scheme. Types and types. General requirements for implementation.

2. Frolov V.V. Language of radio circuits.

3. Zgut M.A. Symbols and radio circuits.

When developing power and lighting networks and automatic control systems, various types and types of electrical equipment, wiring, instruments and automation equipment are used, connected to the control object and to each other according to certain schemes. Depending on the equipment used. instruments and automation equipment (electrical, pneumatic, hydraulic, etc.), various schemes for their connections are being developed.

In accordance with GOST 2.701-76, schemes are divided into the following types and types:

Types of schemes:

Electrical – E;

Hydraulic – G;

Pneumatic – P;

Kinematic – K;

Combined – S.

Types of schemes:

Structural – 1;

Functional – 2;

Fundamental – 3;

Connections – 4;

Connections – 5;

General – 6;

Locations – 7.

Electrical A diagram is a simplified visual representation of the connections between individual elements of an electrical circuit, made using conventional graphic symbols and allowing one to understand the principle of operation of an electrical installation.

Structural – reflect the enlarged structure of the management system and the relationship between control and management points of objects. The main elements are depicted as rectangles, the connections between the elements are shown by arrows directed from the influencing element to the affected one.

Functional diagram - reflects the functional block structure of individual units of automatic control, signaling, control and regulation of the technological process and determining the equipment of the control object with instruments and automation equipment.

Fundamental diagrams - reflect with sufficient completeness the composition of the elements, auxiliary equipment and connections between them included in a separate automation unit and giving a detailed idea of ​​the principle of its operation. Based on the schematic diagrams, external and internal connection diagrams are developed.

Connection diagrams – shows information about the internal connections of the product.

Connection diagram – contains information about connections between individual elements of electrical installations and working mechanisms.

General schemes– contain general and specific information on the project.

Layout diagram – explains the location of devices in space, contains information about the routes and methods of laying electrical wiring.

Of the 7 types of electrical circuits, the main ones are circuit diagrams , reflecting with sufficient completeness and clarity the mutual connections between the individual elements that make up the installation and providing comprehensive information about the principle of its operation.

Schematic diagrams serve as the basis for the development of connection diagrams and connections, drawing up specifications and applications for equipment, instruments and devices at the stage of preparation for installation. At the stage of installation, commissioning and operation of the installation, the schematic diagram is the main guiding technical document.

According to their purpose, circuit diagrams are divided into power circuit diagrams (main current circuits), auxiliary circuit diagrams (control, monitoring, alarm circuits), and combined circuits. When the diagrams are drawn together, the main current circuits are highlighted with bolder lines.

Circuit diagrams can be carried out combined And spaced ways. Combined images (Fig. 2.3, a) are used in diagrams, with all parts of each device located in close proximity and usually enclosed in a rectangular and round outline made with a thin line. Most often, circuit diagrams are made in a spaced manner (Fig. 2.3, b), in which the conventional graphic symbols of the component parts of the devices are placed in different places, but in such a way that the individual circuits are depicted most clearly. The belonging of different parts to the same apparatus is established by a positional designation. Individual elements of equipment (switches, fuses, electromagnetic starters, relays, resistors, capacitors, etc.) are connected to each other by wires and cables using connection diagrams , which are a document attached by the manufacturer of an electrical installation or device, containing information about internal product connections. On connection diagrams, devices and devices are depicted in a simplified form in the form of rectangles, above which there is a circle divided by a horizontal line. The numbers in the numerator indicate the serial number of the product, the denominator contains the alphanumeric designation of the element in accordance with GOST 2.710-81 (see Fig. 2.4).

Figure 2.3. Basic electrical circuits for controlling electrical wires: a) combined; b) spaced apart.

Figure 2.4. Electrical connection diagram.

Electrical, as well as technological equipment, is installed on supporting bases (for example, in workshops), using the diagrams shown on the plans of buildings and structures and drawings, called in this case layout diagrams . The layout diagram explains the location of the devices in space and contains information about the routes and methods of laying wires (Fig. 2.5)

Figure 2.5. Layout diagram.

Information on connections between individual devices (cabinets, consoles, control panels, terminals of electrical installation elements) and the specifics of making such connections is contained in connection diagrams (Fig. 2.6).

Figure 2.6. Connection diagram.

Switching devices in the diagrams are shown in a switched-off state (i.e., in the absence of current in the windings of relays, contactors, electromagnetic starters, etc. and external forced forces acting on individual devices).

To identify circuit sections and draw up connection diagrams, circuits in circuit diagrams are marked. AC power circuits are marked with phase letters and sequential numbers. Thus, three-phase alternating current circuits are marked with the letters A, B, C, N, two-phase current circuits - A, B; B, C; C, A - and single-phase current - A, N; B,N; C, N.

In DC circuits, sections of circuits with positive polarity are assigned odd numbers, and those with negative polarity are assigned even numbers. The input and output sections of the circuit are marked with polarity: plus (+) and minus (-), and the middle conductor is marked with the letter N or M. DC circuits can be marked with sequential numbers.

Control, protection, alarm, automation, and measurement circuits are marked with sequential numbers within the product.

On the diagrams, markings are placed at the ends or in the middle of the chain section, to the left of the image of the vertical chain and above the image of the horizontal chain.

Connection diagrams can have either graphic method drawings, when wires, harnesses and cables connecting the terminals of devices are shown on the diagram as separate lines (similar to how a circuit diagram is performed in a combined way (see Fig. 2.3, a), lines of one direction can be depicted as one thickened one, which branches off at the connection points on separate lines, or, if it is difficult to read them, address method , in which the lines representing wires, harnesses and cables are broken near the connection points (Fig. 2.4). At the terminals of the devices, only pieces of wire are shown, on the shelves of which they are written in the form of a fraction, in which the numerator is the serial number of the product or its alphanumeric designation; the denominator is the contact number, for example 1/3 or IM/3.

In the places where the cores of wires and cables are connected to the devices, the connection diagrams show the output terminals in the form of circles, inside which their markings (factory or specially assigned) are affixed.

With a high level of automation and a large number of equipment in the circuit, installation of electrical wiring is carried out according to connection diagrams, which are compiled in the form of tables where information about the wires and connection addresses are recorded, Table 2.3.

1) symbols defined by GOST 2.751-73, GOST 2.755-74, GOST 2.756-76;

2) the principle of operation of individual devices included in the installation;

3) properties of serial and parallel connection of contacts and other circuit elements.

When reading the diagrams, you should follow a certain sequence:

Determine the power source and the main energy paths from source to consumer;

Divide the circuit into simple circuits;

Understand the role of each element included in individual simple chains;

Consider the conditions for the interaction of devices included in the electrical installation.

Table 2.3 Wiring connections.

Conductor	Where does it come from?	Where does it go?	Wire data	Note
Front wall
60 K 4/8 K 5/17 PV 1x1
58 K 4/17 K 5/8
59 K 4/ HT/ 3
21 I/5 HT/ 7

We must start by considering the circuit of the main apparatus that controls the operation of the consumer. Then determine which devices’ contacts are included in this circuit and how they affect the operation of the main device. Then you should consider the circuits of the devices that control these contacts, etc.

Let us consider as an example the operation of the circuit shown in Fig. 2.3. The greatest clarity in reading (individual circuits are better traced) is provided by a circuit made in a spaced manner (Fig. 2.3, b). The diagram shows that the electric motor (M) is powered from a 380/220 V network with a frequency of 50 Hz. The electrical circuit is protected from short circuit by the QF circuit breaker. Remote start and stop - by an electromagnetic starter (KM), equipped with an electrothermal relay (KK) to protect it from overloads. The electric motor is controlled by the “start” and “stop” buttons (SB).

When you press SB (the "start" button with a closing contact) and the circuit breaker QF is on, a closed electrical circuit is formed: clamp C1-break contact with self-reset SB ("stop" button), normally open contact SB, coil of the electromagnetic starter KM, break contact of the electrothermal relay KK, neutral wire networksN. A magnetic field is created in the electromagnet KM. The anchor, being attracted to the core, drags the traverse on which the movable main and blocking contacts are fixed. The power contacts of the KM close the main current circuit (the electric motor turns on), and the blocking contact of the KM bypasses the “start” button, since it is spring-loaded and is closed only when pressed (therefore, the blocking contact of the KM is often called the self-power contact).

To stop the electric motor, press the button SВ with normally open contacts ("stop"). In this case, the KM coil is de-energized, the main contacts of the electromagnetic starter will open and turn off the electric motor. The electric motor is protected from overloads by a thermal relay KK, which operates as follows. If the specified value of the electric current in the electric motor power circuit is exceeded, the thermal relay KK will operate and, with its opening contact, will open the power circuit of the electromagnetic starter coil, which in turn will lead to the opening of its main contacts and the electric motor will turn off.

The circuit also provides light signaling for the operation of the electric motor. When the electric motor is not running, the warning light HL2 is on, and when the motor is running, HLI is on.

Sequence of reading block diagrams:

On the drawing in question we read all the inscriptions;

We find out the meaning of all unfamiliar symbols and images;

Consistently review unit control and production panels, dispatch panels and consoles;

Determine the types and directions of operational communication between control and management points.

Find out the connections between the management structure in question and other levels of management.

Conventional alphabetic and graphic designations on electrical circuit diagrams

When executing the diagrams, the following graphic symbols are used:

1) conventional graphic symbols established in the standards of the Unified System of Design Documentation, as well as those built on their basis;

2) rectangles;

3) simplified external outlines (including axonometric ones).

If necessary, non-standardized graphic symbols are used.

When using non-standardized conventional graphic symbols and simplified external outlines on the diagram, appropriate explanations are given.

Conventional graphic symbols, for which several acceptable (alternative) embodiments have been established, differing in geometric shape or degree of detail, should be used based on the type and type of the diagram being developed, depending on the information that needs to be conveyed on the diagram by graphic means. In this case, on all diagrams of the same type included in the documentation set, one selected designation option must be used.

The use of certain graphic symbols on diagrams is determined by the rules for executing diagrams of a certain type and type.

Conventional graphic symbols of elements are depicted in the sizes established in the standards for conventional graphic symbols.

The dimensions of the conventional graphic symbols, as well as the thickness of their lines, must be the same on all diagrams for a given product (installation).

Notes :

1. All sizes of graphic symbols can be changed proportionally.

2. Conventional graphic symbols of elements used as components of the symbols of other elements (devices) may be depicted smaller in comparison with other elements (for example, a resistor in a rhombic antenna, valves in a dividing panel).

Graphic symbols on diagrams should be made with lines of the same thickness as the communication lines.

Symbolic graphic symbols of elements are shown on the diagram in the position in which they are given in the relevant standards, or rotated by an angle multiple of 90°, if there are no special instructions in the relevant standards. It is allowed to rotate conventional graphic symbols by an angle that is a multiple of 45, or depict them as mirror images.

If, when rotating or mirroring conventional graphic symbols, the meaning or readability of the symbol may be impaired, then such symbols must be depicted in the position in which they are given in the relevant standards.

Communication lines are made with a thickness of 0.2 to 1.0 mm, depending on the format of the diagram and the size of the graphic symbols. Recommended line thickness is from 0.3 to 0.4 mm.

Communication lines should consist of horizontal and vertical segments and have the least number of kinks and mutual intersections.

In some cases, it is possible to use inclined sections of the communication line, the length of which should be limited as much as possible.

3. Communication lines passing from one sheet or one document to another should be broken outside the diagram image without arrows.

Next to the communication line break, the designation or name assigned to this line should be indicated (for example, wire number, pipeline number, signal name or its abbreviated designation, etc.), and in parentheses the sheet number of the circuit and zone, if any. when the diagram is executed on several sheets, for example, sheet 5, zone A6 (5, A6), or the designation of the document, when the diagrams are executed as independent documents, to which the communication line passes.

Communication lines should usually be shown in full. Communication lines within one sheet, if they make it difficult to read the diagram, can be cut off. Broken communication lines are ended with arrows. Near the arrows indicate the locations of broken lines, for example, connections, and (or) the necessary characteristics of the circuits, for example, polarity, potential, pressure, fluid flow, etc.

Elements (devices, functional groups) included in the product and shown in the diagram must have designations in accordance with the standards for the rules for implementing specific types of circuits.

Designations can be alphabetic, alphanumeric and numeric. Designations of elements (devices, functional groups) specific to certain branches of technology must be established by industry standards.

Equipment and installations on power and lighting network plans are presented in accordance with GOST 21.614-84 “Conventional graphic images of electrical equipment and wiring on plans.” The main conventional graphic images on the power and lighting network plans are presented in Table 2.4, and the symbols of electrical devices in Table 2.4.

The dimensions of the images are given in the drawings on a scale of 1:100. When making images on other scales, the size of the images should be changed in proportion to the size of the drawing, and the size (diameter or side) of the conventional image of the electrical equipment should be at least 1.5 mm. The dimensions of images of switchboards, cabinets, consoles, boxes, electrical devices and electrical equipment of open distribution devices should be taken according to their actual dimensions on the scale of the drawing. It is allowed to increase their size to be able to depict all the pipes with wiring suitable for them.

Table 2.4. Conventional graphic images on plans of power and lighting networks.

	Name	Image
I. Electrical wiring.
1. Designation of electrical wiring lines.
	General image
	Three wire line
	36 V line
	Grounding line
2. Open wiring.
	Open cable routing
	Cable wiring
	Wiring in the tray
	Wiring in the box
	Laying wiring under the baseboard
3. Wiring in pipes.
	General designation
	Open gasket
	Hidden gasket
	The posting goes to a higher level or comes from a high
	The posting goes to a lower level or comes from a low
II.
	Equipment.
	Branch box
	Introductory box
	Box, drawer
	Box, drawer with clips
	Main panel for working lighting
	Panel of group working lighting
	Cabinet, panel with one-way service
	Cabinet, panel with double-sided service
	Switch, general designation Switch for surface installation with IP 20, IP23: Single pole Bipolar
	Three-pole Switch for surface installation with IP 20, IP23: Single pole Bipolar
	Switch for hidden wiring: Switch for surface installation with IP 20, IP23: Single pole Bipolar
	Switch for surface installation with IP 44, IP55:
	Switches with IP 20, IP23
	Open two-pole socket with IP 20, IP23
	Open two-pole double socket with IP 20, IP23
	Hidden socket socket, two-pole
	Plug socket open two-pole double
	Open two-pole socket with IP 44, IP55
	Socket with protective contact with IP 44, IP55
	Incandescent lamp
	Lamp with incandescent lamp on a cable
	Lamp with incandescent lamp on bracket
	Lamp with GLND
	Lamp with GLVD
	Spotlight
	Wall cartridge
	Suspended chuck

Magnetic switch

There are several different types of electrical circuits, and any competent electrician must understand why they are needed, how they differ from each other, what information they contain, what symbols are used on different circuits, and how to read them correctly.

By type, all electrical circuits are divided into functional, structural, principle, connections and connections (installation) and location. There are special types of diagrams, such as external electrical and piping diagrams, and cable routing diagrams. They are used to install and connect wiring to electrical equipment and automation equipment.

The most common type of electrical circuit is electrical circuit diagrams. They give a clear understanding of the operation of the installation, since such diagrams show all electrical circuits. On electrical circuit diagrams, symbols depict all electrical elements, apparatus and devices, taking into account the actual sequence of their operation.

If this is a diagram of a machine, then the power part of the diagram (electric motors and all the devices through which they are connected) and the control circuit are shown separately. All elements on the circuit diagrams have alphanumeric designations, which are carried out in accordance with GOST.

The diagrams are usually supplemented by various diagrams and tables of contact switching, which explain the order of operation of complex elements, such as multi-position switches, timing diagrams showing the sequence of operation of relay coils.

The diagram may contain a specification with a list of electrical devices and other electrical devices and elements included in the diagram, as well as additional explanatory notes. After reading the circuit diagram, you can study and fully understand how the electrical equipment of an installation or machine works.

Electrical circuit diagrams can be made in a combined or separated way. The combined method is usually used to create relatively simple circuit diagrams. Schemes in which there are several engines and a developed control circuit are in most cases carried out in a spaced manner.

Individual elements of the symbols of electrical devices are located in different places on the diagram, which increases the clarity and simplifies the reading of the diagrams.

To read circuit diagrams, you need to know the algorithm for the functioning of the circuit, understand the principle of operation of devices, devices and automation systems on the basis of which the circuit diagram is built.

The electrical circuit diagram is used to check the correctness of electrical connections during installation and commissioning of electrical equipment. Such diagrams are indispensable in operation and troubleshooting during repairs. Although I once met old electricians at a factory working without diagrams (often they simply did not exist), this still does not mean anything. In this case, people were helped out by simply having experience in servicing the same machines for a long time.

If you do not have such experience, then troubleshooting even in the electrical equipment of machines of relatively low complexity can cause serious difficulties and take hours. Therefore, the electrical circuit diagram is the main lifesaver of any electrician. Thanks to it, any malfunction can be detected and eliminated in a very short time.

Using electrical circuit diagrams design wiring diagrams and connections. In another way, such diagrams are popularly called installation diagrams. Such diagrams show the actual location of electric motors, electrical devices and other automation elements on the machine, in cabinets and on control panels. All elements are not carried out in the same way according to the same GOSTs as in the circuit diagrams.

Simplified diagram of connections and connection of a three-phase motor using two magnetic starters:

All wires in the connection and connection diagram have their own unique number, which is applied to the wire after installation of the actual circuit. In such diagrams, wires going in one direction are often combined into bundles or bundles and shown as one thick line. All wire connections are made only at the terminals of electrical devices or using. All connections between parts of individual cabinets and control panels are also made through the terminal block, which greatly facilitates the maintenance of the electrical equipment of the machines in the future.

If in circuit diagrams individual elements of the same device can be located in different parts of the circuit, for example, the starter coil is in control circuits, and the contacts are in power circuits, then in the wiring diagram all elements of the same starter are shown side by side. In this case, the terminals of the device on the diagram are numbered in the same way as on the real device.

For example, for a starter, the coil terminals are numbered - A - B, power contacts - 1-2, 3-4, 5-6, blocking contacts 13-14. This greatly simplifies the installation of electrical equipment. The person who does this does not have to think about where to place the device itself (this is already shown in the diagram) and where to connect which wire. Since the presence of a number on the blocking contact “13-14” indicates that this contact is normally open. If the contact were normally closed, then the number would be “11-12”.

Very often, in the passports of machine tools, connection and connection diagrams are shown separately. Connection diagrams indicate the contours of a machine or installation, the main elements - motors, devices located on the machine itself (position switches, sensors, electromagnets), cabinets and control panels, as well as electrical wiring that connects it all. Cabinets and control panels are shown as empty contours with terminal blocks to which wires are led. And the connection diagrams show only a specific control cabinet with all the devices included in it and the wiring. At the same time, the connection diagrams focus on describing the location and methods of fastening wires, harnesses, pipes, electrical devices and electric motors on the machine itself.

There are several options for connection and connection diagrams. One of the most popular methods recently is the address method. In this method, the wires are not shown on the diagrams, but are only designated by numbers near the terminals of electrical devices. Although such a scheme is easier to implement using computer programs, in my opinion, it turns out to be much more complicated and often leads to errors during installation.

In addition to electrical fundamentals and installations, common structural and functional diagrams. They help to understand the general operating principle of any complex equipment or individual elements. Structural diagrams differ from functional diagrams in that in diagrams of the first type the main functional parts of the device are defined and designated, while in functional diagrams the processes that occur in them are explained, i.e. The principle of operation of the device is explained.

For example, such circuits are very popular when describing the operating principle of complex electronic devices. In this case, a detailed circuit diagram can only confuse and frighten, especially inexperienced electricians, who for the most part are very afraid of various electronics. And so, having understood from the structural diagram what individual blocks the device consists of, how these blocks interact with each other, having understood from the functional diagram how specific blocks and elements of the device work and then turning to the problematic part on the circuit diagram, you can quickly solve any problem that arises.

There are also combined schemes. These diagrams may show several types of diagrams, such as an electrical circuit and wiring, or a circuit and layout. The structural diagram can be combined with the functional one.

A schematic electrical diagram is a drawing that shows all the components of a particular object. In particular, elements of such types as electromagnetic, magnetic and electromagnetic communication. The drawings also include the parameters of the elements presented in the drawing.

Types of electrical circuits

What types of electrical circuits are there? They differ according to various criteria, but must be clearly marked on the drawings, correctly, after careful checking. An electrical diagram is a graphical image that shows the connections between power supply devices, by reading which you can become familiar with how an electrical device works.

The elements of such a scheme include:

• Winding of an electric machine;
• Coil with contactors in the relay;
• Contacts in electrical equipment;
• Resistor and more.

Thanks to a conventional graphic image, those elements in the electrical circuit that are responsible for receiving, converting and controlling voltage flows in the network are displayed.

Display of electrical connections is carried out through wires and cables.

Depending on what the diagram is intended for, it can be structural, functional, schematic or complete, installation. If the diagram is single-line and simplified, then the wires and connection points are depicted as one line. Due to the segments that will intersect the line at an angle of 45ᵒ, it is shown how many wires and cable cores should be present there.

What is a wiring diagram

The installation type of electrical diagrams allows you to depict the places where the components of each electrified equipment are located in detail so that you can determine the method of laying the wiring.

Electrical circuit drawings are needed for:

• Correct arrangement of elements;
• Checking their location after repair;
• Room service to find a specific object without difficulty.

A diagram of how connections are made is also included here, and subsequently, using such data, installation of the device, maintenance and repair work are carried out. The diagram must necessarily include not only the basic principles by which you can approach the elements, but also additional ones in case of an emergency.

The image is carried out on a miniature scale, but with maximum accuracy.

The installation diagram includes internal connection diagrams indicating how the units installed inside are connected, and it is also necessary to mark the external connection diagram, with an exact indication of cable routing. It is worth noting that the marking of each electrical terminal of the device and the end of the current-carrying core has a marking, which must be included on the diagram.

As for guidelines on how to read such electrical diagrams, recommendations should be made for each drawing, which indicates the sequence of reading the data. First, the types and types of the circuit are read by name from the place where the corner stamp is applied. Next you need to examine the description of power circuits, and reading begins with the source of electricity. The control circuit is studied in as much detail as possible.

If there are circuits that contain electronic elements, then you need to study each individual element, for example, Mega48PA, paying attention to how they conduct electrical charges through each semiconductor element. It is important to remember that the power supply in the main circuit in electronic devices is considered single-wire, and therefore the final part of the circuit is shown by connecting to the housing of certain equipment.

Types and types of electrical circuits

Electrical circuit diagrams are further divided into 2 categories. One displays power type networks and is a three-line diagram. The purpose of the drawings is quite clear, since they allow you to detect the location of the elements of the electrical circuit.

According to the GOST standard, each electrical circuit is divided into 7 types:

• Structural;
• Functional;
• Principled;
• Assembly;
• Connections;
• General;
• Layout diagram.

Depending on what the diagram in the drawing is for, it may be in the form of a circuit that supplies power to the network, or in other words, you need to show each power source and the lines through which current comes. There are circuits responsible for the distribution of the circuit diagram network, which combines the 2 previous types of circuits, which is suitable for small objects.

Description of the electrical block diagram

In addition to the basic electrical wiring diagram, one of the most common is the structural and functional diagram. They are intended for a more accurate understanding of the general operating principle of each equipment, in particular, complex types or individual small components of the circuit.

Depending on the type of diagram, the following points are noted:

• Places of connections of elements;
• Places where elements are connected to the general power supply network;
• The order of connecting elements.

Structural differs from functional in that it defines and designates the main functional part of each device. A functional type diagram explains the process occurring in the circuit. In other words, it explains how the device works.

These types of circuits are popular in describing the operating principle of a complex electronic device, regardless of its type.

In this case, the use of a detailed circuit diagram can be misleading and confusing in operation. If you study the block diagram in detail, you can find out what individual elements a complex device consists of, and how each block works separately.

Classification and types of drawings and their purpose

Are there any differences between the drawings? Is there a general classification and why is it needed? It is worth noting that the drawings are made strictly in accordance with the requirements of GOST, since amateur activities are strictly unacceptable, and this can cause serious consequences.

Examples of drawings can be very different, depending on the field of activity, but they are classified into:

• Detailed;
• Assembly;
• General;
• Theoretical;
• Dimensional;
• Mounting;
• Electrical installation;
• Sketch;
• Photo drawing;
• Schematic.

If you study this topic in more detail, you can discover a lot of subtleties. For example, some drawings consist of several views of other drawings. For example, an assembly drawing includes hydraulic installation, pneumatic installation, and electrical installation.

On the installation drawing, in addition to displaying the electrical equipment that will be connected to the network, it is necessary to mark out the room with its features.

In addition, drawings may differ in the way they are made and how they will be used. Namely, there are originals, originals, duplicates, copies. Each drawing produced in production requires maximum concentration, attention and a responsible, competent approach.

Why is an electrical functional diagram necessary?

There is another type of electrical circuit called functional. It is required in order to explain the process carried out in each individual functional circuit of a particular device and several products simultaneously. In order to designate complex equipment, you need to create several functional diagrams, each of which will be responsible for explaining a separate process that occurs under a specific operating mode.

It depends on the characteristics of the equipment:

• How many functional diagrams will be developed;
• To what degree of detail will they be displayed;
• At what scale will the drawing be drawn up?

The diagram must show all functional parts of the equipment. In particular, constituent elements, devices, functional groups, connections between them. By graphically constructing diagrams, you can get a visual reflection of the sequence in which the functional process occurring inside the product occurs.

It is worth noting that it is permissible not to take into account the actual location of each element.

In order to identify each functional part between the elements of the product, it will be necessary to use conventional graphic images in accordance with established standards for a specific group of elements. In this option, you should be guided by the rules by which the schematic diagram is drawn up. To display each individual functional part on the diagram, you can use rectangles. This will resemble the view of a block diagram.

A functional diagram can be used to indicate a functional group, for which the designation assigned to it in the preparation of the circuit diagram is used, each of the components of the product, for which conventional graphic images are used, in particular letters, numbers that were indicated in the circuit diagram, and all devices, marked with a rectangle icon, which was assigned when drawing up the circuit diagram. As a rule, those elements for which a rectangle was used should be labeled directly on the diagram inside this rectangle. If there are any abbreviations, the decoding is noted in the margins in the diagram.

What is a circuit diagram (video)

Only professionals with experience and appropriate education should draw up electrical diagrams, which will eliminate problems when reading and directly using the document for installation, maintenance and repair later.