Each electrical circuit consists of many elements, which, in turn, also include various parts in their design. The most striking example is household appliances. Even a regular iron consists of a heating element, temperature regulator, pilot light, fuse, wire and plug. Other electrical appliances have an even more complex design, complemented by various relays, circuit breakers, electric motors, transformers and many other parts. An electrical connection is created between them, ensuring full interaction of all elements and each device fulfilling its purpose.
In this regard, the question very often arises of how to learn to read electrical diagrams, where all components are displayed in the form of conventional graphic symbols. This problem is of great importance for those who regularly deal with electrical installations. Correct reading of diagrams makes it possible to understand how the elements interact with each other and how all work processes proceed.
Types of electrical circuits
In order to correctly use electrical circuits, you need to familiarize yourself in advance with the basic concepts and definitions affecting this area.
Any diagram is made in the form of a graphic image or drawing, on which, together with the equipment, all the connecting links of the electrical circuit are displayed. There are different types of electrical circuits that differ in their intended purpose. Their list includes primary and secondary circuits, alarm systems, protection, control and others. In addition, there are and are widely used principled and fully linear and expanded. Each of them has its own specific features.
Primary circuits include circuits through which the main process voltages are supplied directly from sources to consumers or receivers of electricity. Primary circuits generate, convert, transmit and distribute electrical energy. They consist of a main circuit and circuits that provide their own needs. The main circuit circuits generate, convert and distribute the main flow of electricity. Self-service circuits ensure the operation of essential electrical equipment. Through them, voltage is supplied to the electric motors of the installations, to the lighting system and to other areas.
Secondary circuits are considered to be those in which the applied voltage does not exceed 1 kilowatt. They provide automation, control, protection, and dispatch functions. Through secondary circuits, control, measurement and metering of electricity are carried out. Knowing these properties will help you learn to read electrical circuits.
Full-linear circuits are used in three-phase circuits. They display electrical equipment connected to all three phases. Single-line diagrams show equipment located on only one middle phase. This difference must be indicated on the diagram.
Schematic diagrams do not indicate minor elements that do not perform primary functions. Due to this, the image becomes simpler, allowing you to better understand the principle of operation of all equipment. Installation diagrams, on the contrary, are carried out in more detail, since they are used for the practical installation of all elements of the electrical network. These include single-line diagrams displayed directly on the construction plan of the facility, as well as diagrams of cable routes along with transformer substations and distribution points plotted on a simplified general plan.
During the installation and commissioning process, extensive circuits with secondary circuits have become widespread. They highlight additional functional subgroups of circuits related to switching on and off, individual protection of any section, and others.
Symbols in electrical diagrams
Every electrical circuit contains devices, elements, and parts that together form a path for electrical current. They are distinguished by the presence of electromagnetic processes associated with electromotive force, current and voltage, and described in physical laws.
In electrical circuits, all components can be divided into several groups:
- The first group includes devices that generate electricity or power sources.
- The second group of elements converts electricity into other types of energy. They perform the function of receivers or consumers.
- The components of the third group ensure the transfer of electricity from one element to another, that is, from the power source to electrical receivers. This also includes transformers, stabilizers and other devices that provide the required quality and voltage level.
Each device, element or part corresponds to a symbol used in graphic representations of electrical circuits, called electrical diagrams. In addition to the main symbols, they display the power lines connecting all these elements. The sections of the circuit along which the same currents flow are called branches. The places of their connections are nodes, indicated on electrical diagrams in the form of dots. There are closed current paths that cover several branches at once and are called electrical circuit circuits. The simplest electrical circuit diagram is single-circuit, while complex circuits consist of several circuits.
Most circuits consist of various electrical devices that differ in different operating modes, depending on the value of current and voltage. In idle mode, there is no current in the circuit at all. Sometimes such situations arise when connections are broken. In nominal mode, all elements operate with the current, voltage and power specified in the device passport.
All components and symbols of the elements of the electrical circuit are displayed graphically. The figures show that each element or device has its own symbol. For example, electrical machines may be depicted in a simplified or expanded manner. Depending on this, conditional graphic diagrams are also constructed. Single-line and multi-line images are used to show winding terminals. The number of lines depends on the number of pins, which will be different for different types of machines. In some cases, for ease of reading diagrams, mixed images can be used, when the stator winding is shown in expanded form, and the rotor winding is shown in a simplified form. Others are performed in the same way.
They are also carried out in simplified and expanded, single-line and multi-line methods. The way of displaying the devices themselves, their terminals, winding connections and other components depends on this. For example, in current transformers, a thick line, highlighted with dots, is used to depict the primary winding. For the secondary winding, a circle can be used in the simplified method or two semicircles in the expanded image method.
Graphic representations of other elements:
- Contacts. They are used in switching devices and contact connections, mainly in switches, contactors and relays. They are divided into closing, breaking and switching, each of which has its own graphic design. If necessary, it is allowed to depict the contacts in a mirror-inverted form. The base of the moving part is marked with a special unshaded dot.
- . They can be single-pole or multi-pole. The base of the moving contact is marked with a dot. For circuit breakers, the type of release is indicated in the image. Switches differ in the type of action; they can be push-button or track, with normally open and closed contacts.
- Fuses, resistors, capacitors. Each of them corresponds to certain icons. Fuses are depicted as a rectangle with taps. For permanent resistors, the icon may have taps or no taps. The moving contact of a variable resistor is indicated by an arrow. The pictures of capacitors show constant and variable capacitance. There are separate images for polar and non-polar electrolytic capacitors.
- Semiconductor devices. The simplest of them are pn junction diodes with one-way conduction. Therefore, they are depicted in the form of a triangle and an electrical connection line crossing it. The triangle is the anode, and the dash is the cathode. For other types of semiconductors, there are their own designations defined by the standard. Knowing these graphical drawings makes reading electrical circuits for dummies much easier.
- Sources of light. Available on almost all electrical circuits. Depending on their purpose, they are displayed as lighting and warning lamps with corresponding icons. When depicting signal lamps, it is possible to shade a certain sector, corresponding to low power and low luminous flux. In alarm systems, along with light bulbs, acoustic devices are used - electric sirens, electric bells, electric horns and other similar devices.
How to read electrical diagrams correctly
A schematic diagram is a graphical representation of all the elements, parts and components between which an electronic connection is made using live conductors. It is the basis for the development of any electronic devices and electrical circuits. Therefore, every novice electrician must first master the ability to read a variety of circuit diagrams.
It is the correct reading of electrical diagrams for beginners that allows you to understand well how to connect all the parts to get the expected end result. That is, the device or circuit must fully perform its intended functions. To correctly read a circuit diagram, it is necessary, first of all, to familiarize yourself with the symbols of all its components. Each part is marked with its own graphic designation - UGO. Typically, such symbols reflect the general design, characteristic features and purpose of a particular element. The most striking examples are capacitors, resistors, speakers and other simple parts.
It is much more difficult to work with components represented by transistors, triacs, microcircuits, etc. The complex design of such elements also implies a more complex display of them on electrical circuits.
For example, each bipolar transistor has at least three terminals - base, collector and emitter. Therefore, their conventional representation requires special graphic symbols. This helps distinguish between parts with individual basic properties and characteristics. Each symbol carries certain encrypted information. For example, bipolar transistors may have completely different structures - p-p-p or p-p-p, so the images on the circuits will also be noticeably different. It is recommended that you carefully read all the elements before reading the electrical circuit diagrams.
Conditional images are often supplemented with clarifying information. Upon closer examination, you can see Latin alphabetic symbols next to each icon. This way, this or that detail is designated. This is important to know, especially when we are just learning to read electrical diagrams. There are also numbers next to the letter designations. They indicate the corresponding numbering or technical characteristics of the elements.
The ability to read electrical diagrams is an important component, without which it is impossible to become a specialist in the field of 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 remote controls 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 circuits 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, such as 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
In this article we will look at the designation of radio elements on diagrams.
Where to start reading diagrams?
In order to learn how to read circuits, first of all, we must study what a particular radio element looks like in a circuit. In principle, there is nothing complicated about this. The whole point is that if the Russian alphabet has 33 letters, then in order to learn the symbols of radio elements, you will have to try hard.
Until now, the whole world cannot agree on how to designate this or that radio element or device. Therefore, keep this in mind when you collect bourgeois schemes. In our article we will consider our Russian GOST version of the designation of radioelements
Studying a simple circuit
Okay, let's get to the point. Let's look at a simple electrical circuit of a power supply, which used to appear in any Soviet paper publication:
If this is not the first day you have held a soldering iron in your hands, then everything will immediately become clear to you at first glance. But among my readers there are also those who are encountering such drawings for the first time. Therefore, this article is mainly for them.
Well, let's analyze it.
Basically, all diagrams are read from left to right, just like you read a book. Any different circuit can be represented as a separate block to which we supply something and from which we remove something. Here we have a circuit of a power supply to which we supply 220 Volts from the outlet of your house, and a constant voltage comes out of our unit. That is, you must understand what is the main function of your circuit?. You can read this in the description for it.
How are radioelements connected in a circuit?
So, it seems that we have decided on the task of this scheme. Straight lines are wires or printed conductors through which electric current will flow. Their task is to connect radioelements.
The point where three or more conductors connect is called knot. We can say that this is where the wiring is soldered:
If you look closely at the diagram, you can see the intersection of two conductors
Such intersection will often appear in diagrams. Remember once and for all: at this point the wires are not connected and they must be insulated from each other. In modern circuits, you can most often see this option, which already visually shows that there is no connection between them:
Here, it is as if one wire goes around the other from above, and they do not contact each other in any way.
If there was a connection between them, then we would see this picture:
Letter designation of radioelements in the circuit
Let's look at our diagram again.
As you can see, the diagram consists of some strange icons. Let's look at one of them. Let this be the R2 icon.
So, let's first deal with the inscriptions. R means . Since we have him not the only one in the scheme, the developer of this scheme gave him the serial number “2”. There are as many as 7 of them in the diagram. Radio elements are generally numbered from left to right and top to bottom. A rectangle with a line inside already clearly shows that this is a constant resistor with a dissipation power of 0.25 Watt. It also says 10K next to it, which means its denomination is 10 Kilohms. Well, something like this...
How are the remaining radioelements designated?
Single-letter and multi-letter codes are used to designate radioelements. Single letter codes are group, to which this or that element belongs. Here are the main ones groups of radioelements:
A – these are various devices (for example, amplifiers)
IN – converters of non-electrical quantities into electrical ones and vice versa. This may include various microphones, piezoelectric elements, speakers, etc. Generators and power supplies here do not apply.
WITH – capacitors
D – integrated circuits and various modules
E – miscellaneous elements that do not fall into any group
F – arresters, fuses, protective devices
H – indicating and signaling devices, for example, sound and light indicating devices
K – relays and starters
L – inductors and chokes
M – engines
R – instruments and measuring equipment
Q – switches and disconnectors in power circuits. That is, in circuits where high voltage and high current “walk”
R – resistors
S – switching devices in control, signaling and measurement circuits
T – transformers and autotransformers
U – converters of electrical quantities into electrical ones, communication devices
V – semiconductor devices
W – microwave lines and elements, antennas
X – contact connections
Y – mechanical devices with electromagnetic drive
Z – terminal devices, filters, limiters
To clarify the element, after the one-letter code there is a second letter, which already indicates element type. Below are the main types of elements along with the letter group:
BD – ionizing radiation detector
BE – selsyn receiver
B.L. – photocell
BQ – piezoelectric element
BR – speed sensor
B.S. – pickup
B.V. - speed sensor
B.A. – loudspeaker
BB – magnetostrictive element
B.K. – thermal sensor
B.M. – microphone
B.P. - pressure meter
B.C. – selsyn sensor
D.A. – integrated analog circuit
DD – integrated digital circuit, logical element
D.S. – information storage device
D.T. – delay device
EL - lighting lamp
E.K. - a heating element
F.A. – instantaneous current protection element
FP – inertial current protection element
F.U. - fuse
F.V. – voltage protection element
G.B. - battery
HG – symbolic indicator
H.L. – light signaling device
H.A. – sound alarm device
KV – voltage relay
K.A. – current relay
KK – electrothermal relay
K.M. - magnetic switch
KT – time relay
PC – pulse counter
PF – frequency meter
P.I. – active energy meter
PR – ohmmeter
PS – recording device
PV – voltmeter
PW – wattmeter
PA – ammeter
PK – reactive energy meter
P.T. - watch
QF
QS – disconnector
RK – thermistor
R.P. – potentiometer
R.S. – measuring shunt
RU – varistor
S.A. – switch or switch
S.B. – push-button switch
SF - Automatic switch
S.K. – temperature-triggered switches
SL – switches activated by level
SP – pressure switches
S.Q. – switches activated by position
S.R. – speed-triggered switches
TV – voltage transformer
T.A. - current transformer
UB – modulator
UI – discriminator
UR – demodulator
UZ – frequency converter, inverter, frequency generator, rectifier
VD – diode, zener diode
VL – electrovacuum device
VS – thyristor
VT –
W.A. – antenna
W.T. – phase shifter
W.U. – attenuator
XA – current collector, sliding contact
XP – pin
XS - nest
XT – collapsible connection
XW – high frequency connector
YA – electromagnet
YB – brake with electromagnetic drive
YC – clutch with electromagnetic drive
YH – electromagnetic plate
ZQ – quartz filter
Graphic designation of radioelements in the circuit
I will try to give the most common designations of elements used in the diagrams:
Resistors and their types
A) general designation
b) dissipation power 0.125 W
V) dissipation power 0.25 W
G) dissipation power 0.5 W
d) dissipation power 1 W
e) dissipation power 2 W
and) dissipation power 5 W
h) dissipation power 10 W
And) dissipation power 50 W
Variable resistors
Thermistors
Strain gauges
Varistors
Shunt
Capacitors
a) general designation of a capacitor
b) variconde
V) polar capacitor
G) trimmer capacitor
d) variable capacitor
Acoustics
a) headphone
b) loudspeaker (speaker)
V) general designation of a microphone
G) electret microphone
Diodes
A) diode bridge
b) general designation of a diode
V) zener diode
G) double-sided zener diode
d) bidirectional diode
e) Schottky diode
and) tunnel diode
h) reversed diode
And) varicap
To) Light-emitting diode
l) photodiode
m) emitting diode in the optocoupler
n) radiation receiving diode in the optocoupler
Electrical quantity meters
A) ammeter
b) voltmeter
V) voltammeter
G) ohmmeter
d) frequency meter
e) wattmeter
and) faradometer
h) oscilloscope
Inductors
A) coreless inductor
b) inductor with core
V) tuning inductor
Transformers
A) general designation of a transformer
b) transformer with winding output
V) current transformer
G) transformer with two secondary windings (maybe more)
d) three-phase transformer
Switching devices
A) closing
b) opening
V) opening with return (button)
G) closing with return (button)
d) switching
e) reed switch
Electromagnetic relay with different groups of contacts
Circuit breakers
A) general designation
b) the side that remains energized when the fuse blows is highlighted
V) inertial
G) fast acting
d) thermal coil
e) switch-disconnector with fuse
Thyristors
Bipolar transistor
Unijunction transistor
Hello, friends! Today we will look at one of the stages of designing electrical devices - drawing up electrical diagrams. However, we will consider them very superficially, since much of what is necessary for design is still unknown to us, and minimal knowledge is already necessary. However, this basic knowledge will help us in the future when reading and drawing electrical diagrams. The topic is quite boring, but rules are rules and must be followed. So…
What is an electrical circuit? What are they? Why are they needed? How to compose them and how to read them? Let's start with what kind of schemes exist in general. In order to unify the preparation of technical documentation (and diagrams are nothing more than part of this documentation) in our country, by Decree of the USSR State Committee for Standards dated August 29, 1984 No. 3038, the State Standard (GOST) “Unified Design System” was introduced documentation. Scheme. Types and types. General requirements for implementation”, otherwise known as GOST 2.701-84, which must comply with any manual or automated diagrams of products from all industries, as well as electrical diagrams of energy structures (power plants, electrical equipment of industrial enterprises, etc.). This document defines the following types of schemes:
- electrical;
- hydraulic;
- pneumatic;
- gas (except pneumatic);
- kinematic;
- vacuum;
- optical;
- energy;
- divisions;
- combined.
We will be primarily interested in the very first point - electrical diagrams that are drawn up for electrical devices. However, GOST also defines several types of circuits depending on the main purpose:
- structural;
- functional;
- fundamental (complete);
- connections (installation);
- connections;
- are common;
- location;
- united.
Today we will look at electrical circuit diagrams and the basic rules for their compilation. It makes sense to consider the remaining types of circuits after the electrical components have been studied, and the training approaches the stage of designing complex devices and systems, then other types of circuits will make sense. What is an electrical circuit diagram and why is it needed? According to GOST 2.701-84, a schematic diagram is a diagram that defines the complete composition of elements and connections between them and, as a rule, gives a detailed idea of the operating principles of the product (installation). Such circuits, for example, were supplied in the documentation for old Soviet televisions. These were huge sheets of paper in A2 or even A1 format, on which absolutely all the components of the TV were indicated. The presence of such a scheme greatly facilitated the repair process. Now such circuits are practically not supplied with electronic devices, because the seller hopes that it will be easier for the user to throw away the device than to repair it. What a marketing ploy! But this is a topic for another discussion. So, a schematic diagram of the device is necessary, firstly, in order to have an idea of what elements are included in the device, secondly, how these elements are connected to each other and, thirdly, what characteristics these elements have. Also, according to GOST 2.701-84, the circuit diagram should provide an understanding of the principles of operation of the device. Here is an example of such a scheme:
Figure 7.1 – An amplification stage based on a bipolar transistor, connected according to a common emitter circuit, with thermal stabilization of the operating point. Electrical circuit diagram
However, we are faced with a small problem: we actually don’t know any electronic elements... What, for example, are the rectangles or parallel lines drawn in Figure 7.1? What do the inscriptions C2, R4, +Epit mean? We will begin our examination of electronic components through the lesson and gradually learn the main characteristics of each of them. And we will definitely study the principle of operation of this device with such a terrible name according to its circuit diagram. Now we will study the basic rules for drawing electrical circuit diagrams. In general, there are a lot of rules, but they are mainly aimed at increasing the clarity and understandability of the diagram, so they will be remembered over time. We will get to know them as needed, so as not to immediately fill our heads with unnecessary information that is not yet necessary. Let's start with the fact that each electrical component on the electrical diagram is indicated by the corresponding conventional graphic symbol (UGO). We will consider the UGO of the elements in parallel with the elements themselves, or you can immediately look at them in GOST 2.721 - 2.768.
Rule 1. Serial numbers for elements (devices) should be assigned, starting with one, within a group of elements (devices) that are assigned the same letter position designation in the diagram, for example, R1, R2, R3, etc., C1, C2, C3, etc. .d. Skipping one or more serial numbers on the diagram is not allowed.
Rule 2. Serial numbers must be assigned in accordance with the sequence of arrangement of elements or devices on the diagram from top to bottom in the direction from left to right. If necessary, it is possible to change the sequence of assigning serial numbers depending on the placement of elements in the product, the direction of signal flow or the functional sequence of the process.
Rule 3. Positional designations are placed on the diagram next to the symbolic graphic designations of elements and (or) devices on the right side or above them. In addition, the intersection of the position designation with communication lines, UGO element or any other inscriptions and lines is not allowed. 
Figure 7.2 – To rule 3
Rule 4. Communication lines should consist of horizontal and vertical segments and have the least number of kinks and mutual intersections. In some cases, it is allowed to use inclined sections of communication lines, the length of which should be limited as much as possible. Intersection of communication lines that cannot be avoided is performed at an angle of 90°.
Rule 5. The thickness of the communication lines depends on the format of the diagram and the size of the graphic symbols and is selected from the range of 0.2 - 1.0 mm. The recommended thickness of communication lines is 0.3 – 0.4mm. Within the diagram, all communication lines must be depicted with the same thickness. It is allowed to use several (no more than three) communication lines of different thicknesses to identify functional groups within the product.
Rule 6. 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.
Rule 7. When indicating the nominal values of elements (resistors, capacitors) near the symbolic graphic symbols, it is allowed to use a simplified method of designating units of measurement: 
Figure 7.3 – To rule 7
Rule 8. The distance between the communication lines, between the communication line and the UGO element, as well as the edge of the sheet must be at least 5 mm.
To begin with, these eight rules are enough to learn how to correctly draw simple electrical circuit diagrams. In we looked at power sources for electrical circuits, in particular, “dry” cells and batteries, and in Lesson 6 we looked at an incandescent lamp as a consumer of electrical energy. Let's, based on the rules described above, try to create a simple circuit diagram consisting of three elements: a source (battery), a receiver (incandescent lamp) and a switch. But first, let’s give the UGO of these elements: 
Now let’s connect these elements in series, assembling an electrical circuit: 
Figure 7.4 – First circuit diagram
Contact SA1 is called a normally open contact because in its initial position it is open and no current flows through it. When SA1 is closed (for example, this could be the switch we all use to turn on the lights at home), the HL1 lamp will light up, powered by the energy of the GB1 battery, and it will burn until the SA1 key opens or the battery power runs out.
This diagram absolutely accurately and clearly shows the sequence of connecting elements and the type of these elements, which eliminates errors when assembling the device in practice.
That's probably all for today, another terribly boring lesson is over. See you soon!
An electrical diagram is a detailed drawing showing all the electronic parts and components that are connected by conductors. Knowledge of the operating principle of electrical circuits is the key to a well-assembled electrical appliance. That is, the assembler must know how electronic elements are indicated on the diagram, what icons, alphabetic or numeric symbols correspond to them. In the material we will understand the key symbols and basics of how to learn to read electrical circuit diagrams.
Any electrical circuit includes a number of parts consisting of smaller elements. Let us take as an example an electric iron, which contains inside a heating element, a temperature sensor, light bulbs, fuses, and also has a wire with a plug. Other household appliances have an advanced configuration with circuit breakers, electric motors, transformers, and between them there are connectors for the full interaction of the components of the device and fulfill the purpose of each of them.
Therefore, the problem often arises of how to learn to decipher electrical diagrams that contain graphic symbols. The principles of reading circuit diagrams are important for those involved in electrical installation, repairing household appliances, and connecting electrical devices. Knowledge of the principles of reading electrical circuits is necessary to understand the interaction of elements and the functioning of devices.
Types of electrical circuits
All electrical circuits are presented in the form of an image or drawing, where, along with the equipment, the links of the electrical circuit are indicated. The circuits differ in purpose, on the basis of which a classification of different electrical circuits has been developed:
- primary and secondary circuits.
Primary circuits are created to supply the main electrical voltage from the current source to consumers. They generate, transform and distribute electricity during transmission. Such circuits require a main circuit and circuits for various needs.
In secondary circuits the voltage is not higher than 1 kW; they are used to provide automation, control and protection tasks. Thanks to secondary circuits, electricity consumption and metering are monitored;
- single-line, full-line.
Full line diagrams are designed for use in three-phase circuits and show devices connected across all phases.
Single line diagrams show only the devices in the middle phase;
- fundamental and installation.
The basic general electrical diagram involves indicating only the key elements; it does not indicate minor details. Thanks to this, the diagrams are simple and understandable.
Wiring diagrams contain more detailed images, since these are the diagrams that are used for the actual installation of all elements of the electrical network.
Expanded diagrams indicating secondary circuits help to highlight auxiliary electrical circuits and areas with separate protection.
Designations in diagrams
Electrical circuits consist of elements and components that ensure the flow of electric current. All elements are divided into several categories:
- devices generating electricity - power sources;
- converters of electric current into other types of energy act as consumers;
- parts responsible for transmitting electricity from the source to the devices. Also included in this category are transformers and stabilizers that ensure voltage stability in the network.
Each element has a specific graphic designation on the diagram. In addition to key symbols, the diagrams indicate power transmission lines. Sections of an electrical circuit through which the same current flows are called branches, and at the places where they are connected, dots are placed on the diagram to indicate connecting nodes.
The circuit of an electrical circuit assumes a closed path of movement of electric current along several branches. The simplest circuit consists of one circuit, and for more complex devices circuits with several circuits are provided.
On an electrical diagram, each element and connection has an icon or symbol. To display insulation pins, single-line and multi-line diagrams are used, the number of lines in which is determined by the number of pins. Sometimes, for ease of reading and understanding of diagrams, mixed drawings are used, for example, stator insulation is described in detail, and rotor insulation is described in general form.
Designations of transformers in electrical circuits are drawn in general or expanded form, using single-line and multi-line methods. The method of displaying devices, their pins, connections and nodes on the diagram directly depends on the detail of the image. Thus, in current transformers, the primary winding is reflected by a thick line with dots. The secondary winding can be displayed as a circle in a standard diagram or two semicircles in the case of an expanded diagram.
Other elements are displayed on the diagrams with the following symbols:
- contacts are divided into make, break and switch contacts, which are indicated by different symbols. If necessary, contacts can be indicated in mirror image. The base of the moving part is indicated as an unshaded dot;
- switches - their base corresponds to a dot, and for automatic switches the category of the release is drawn. A switch for surface installation usually has a separate designation;
- fuses, fixed resistors and capacitors. Safety elements are depicted as a rectangle with taps; fixed resistors can be designated with or without taps. The moving contact is drawn with an arrow. Electrolytic capacitors are designated based on polarity;
- semiconductors. Simple pn junction diodes are shown as a triangle and a crossed circuit line. The triangle represents the anode and the line represents the cathode;
- incandescent lamp and other lighting elements are usually designated
Understanding these icons and symbols makes reading electrical diagrams easy. Therefore, before starting electrical installation or disassembling household appliances, we recommend that you familiarize yourself with the basic symbols.
How to read electrical diagrams correctly
A schematic diagram of an electrical circuit displays all the parts and links between which current flows through conductors. Such diagrams are the basis for the design of electrical devices, so reading and understanding electrical diagrams is a must for any electrician.
A competent understanding of circuits for beginners makes it possible to understand the principles of their composition and the correct connection of all elements in an electrical circuit to achieve the expected result. In order to correctly read even complex diagrams, it is necessary to study the main and secondary images, symbols of the elements. Symbols indicate the general configuration, specifics and purpose of the part, which allows you to get a complete picture of the device when reading the diagram.
You can start familiarizing yourself with circuits with small devices such as capacitors, speakers, resistors. Circuits of semiconductor electronic parts in the form of transistors, triacs, and microcircuits are more difficult to understand. Thus, bipolar transistors have at least three terminals (base, collector and emitter), which requires a larger number of symbols. Thanks to a large number of different signs and patterns, it is possible to identify the individual characteristics of the element and its specificity. The designations contain encrypted information that allows you to find out the structure of the elements and their special characteristics.
Often symbols have auxiliary clarifications - next to the icons there are Latin letter symbols for detail. It is also recommended that you familiarize yourself with their meanings before starting to work with the diagrams. Also, near the letters there are often numbers that display the numbering or technical parameters of the elements.
So, in order to learn to read and understand electrical circuits, you need to become familiar with the symbols (drawings, alphabetic and numerical symbols). This will allow you to obtain information from the diagram regarding the structure, design and purpose of each element. That is, to understand the circuits you need to study the basics of radio engineering and electronics.
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