How is a Switch Designated on a Single Line Diagram of Tires and Busbars

ESKD requirements for the designation of switches

The designation on the circuit breaker diagram is quite clear. It is prescribed in the ESKD, and foreign metric systems are prescribed in accordance with the ISO standard. Moreover, the designation of switches in both of these systems is almost identical. But, as usual, there are also some nuances, to which we will draw your attention in this article.

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. Standards for graphic designation of individual elements in installation and circuit diagrams.

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 circuit breakers have been widely used in Russia for more than a decade, but there is still no single standard according to GOST 2.755-87 for these devices, unlike circuit breakers. It is 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.

Selecting ATS

The table below will help you decide on the type of ATS.

Table 1

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:

• Functional, it shows the node elements (depicted as rectangles), as well as the communication lines connecting them. A characteristic feature of this scheme is minimal detail. To describe the main functions of nodes, the rectangles displaying them are signed with standard letter designations. These can be various parts of the product that differ in functionality, for example, an automatic dimmer with a photo relay as a sensor or a regular TV. An example of such a scheme is presented below.

  
  Example of a functional diagram of a television receiver

• Fundamental. This type of graphic document displays in detail both the elements used in the design and their connections and contacts. The electrical parameters of some elements can be displayed directly in the document, or presented separately in the form of a table.

  
  Example of a circuit diagram of a milling machine

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.

Single Line Diagram Example

• Electrical wiring diagrams. These documents use positional designations of elements, that is, their location on the board, method and order of installation are indicated.

  
  Installation diagram of a stationary flammable gas detector

If the drawing shows the wiring of the apartment, then the locations of lighting fixtures, sockets and other equipment are indicated on the plan. Sometimes you can hear 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.

Installation recommendations

To use the device safely and correctly, the following recommendations must be observed:

• The device must be installed indoors;
• the device must be protected from moisture, as well as from bad climatic conditions;
• the required operating environment temperature for the device ranges from -40 to +55 degrees;
• if the upper part of the contact knife burns, it is necessary to clean it with a file;
• It is necessary that the device is securely and firmly installed.

If the changeover switch is installed outdoors, then it is necessary to ensure protection from environmental influences. It is also necessary to ensure that the device operates within the permissible temperature range - that is, if outdoors, then it is necessary to ensure heating of the cabinet where this switch is installed. Installation, maintenance and repair of the device should only be carried out by a specialist, and only when the power supply is completely disconnected.

Finally, we recommend watching a video that explains in more detail how to connect a changeover switch to the network:

It will be useful to read:

• How to install a diesel generator
• How to connect a three-phase voltage stabilizer
• Connecting the generator to the home network
• What is a load switch used for?

A changeover switch is a special device designed to switch electricity to the necessary devices, operating using a manual drive. Manufacturers offer a wide range of such devices, differing in various technical characteristics.

It is important to remember that there are various options for connecting changeover switches - the choice depends on the characteristics of the electrical network. The most popular switch type switches are in residential buildings. To change the operating characteristics of such devices, control units are used.

In addition, these devices have found application in industry when operating backup generators. When choosing a changeover switch for a generator, you need to take into account its configuration and the specifics of the existing grounding.

The quality of operation of the device is ensured by equipping it with a grounding electrode. Its marking indicates the degree of protection. It is optimal if it is IP30.

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 of electrical circuits.

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:

1. RO opening occurs
2. Closing RO
3. The position of the RO remains unchanged.

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

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

Read also: Ohm's law for parallel connection of resistors

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, you must refer to the regulatory documents; the numbers of 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 display adopted for various types of 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 diagrams, consisting of several components, a broken connection is thus indicated; 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:

1. Closing.
2. Disconnecting.
3. Switching.

• E – Symbol for designating manual switches (buttons).
• F – Group switch (switch).

UGO of electric machines

Let us give several examples of displaying electrical 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:

1. Asynchronous (squirrel-cage rotor).
2. The same as point 1, only in a two-speed version.
3. Asynchronous electric motors with phase-phase rotor design.
4. Synchronous motors and generators.

• B – Collector, DC powered:

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

Designation of electric motors on diagrams

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 graphic symbols for electronic components and measuring instruments

Description of symbols:

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

UGO lighting devices

Let's look at how electric lamps are displayed on a circuit diagram.

An example of how light bulbs are indicated on diagrams (GOST 2.732-68)

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.

An example of an image on the wiring diagrams of flush-mounted sockets

How sockets of other types are depicted is easy to find in the regulatory documents that are available on the Internet.

Designation of flush-mounted switches

Designation of sockets and switches

Connection features

The choice of connection diagram for a changeover switch is influenced by the type of electrical network.

Single-phase network

You can connect such a device to this network only if it has two poles. In addition, you need to take into account that the operation of the switch is only possible if there is a power supply with suitable technical characteristics. As for jumpers that provide contact between two-pole devices, it is advisable to give preference to copper ones.

Before installing such switches in a residential building, it is necessary to check the availability of electrical panels KK202 or their analogues.

Two-phase network

How to connect a switch with your own hands if the network is two-phase? The circuit involves the use of a 200V power supply. Also, for these devices you need to use only expansion switches. Only then can the devices be used in a three-phase power supply network, regardless of the number of modules used.

The maximum voltage for such devices will be 300V, and the maximum negative resistance will be 40 Ohms. The contacts in such devices are applicable exclusively to closed models, and fluctuations in electrical energy are controlled using pass-type capacitors.

Three-phase network

For this type of electrical network, reversible switches are used. They provide a complete uninterrupted supply of electric current, distributing the load over several lines and completely preserving the power supply. Here you need to use 400 V power supplies. It would also be appropriate to use pulse transformers.

Letter designations

In electrical diagrams, in addition to graphic symbols, alphabetic symbols are also used, since without the latter, reading the drawings will be quite problematic. Alphanumeric marking, just like UGO, is regulated by regulatory documents, for electrical this is GOST 7624 55. Below is a table with BO for the main components of electrical circuits.

Letter designations of main elements

Unfortunately, the size of this article does not allow us to provide all the correct graphic and letter symbols, but we have indicated regulatory documents from which all the missing information can be obtained. It should be taken into account that current standards may change depending on the modernization of the technical base, therefore, we recommend monitoring the release of new additions to regulations.

If for an ordinary person the perception of information occurs by reading words and letters, then for mechanics and installers they are replaced by alphabetic, digital or graphic symbols. The difficulty is that while the electrician completes his training, gets a job, and learns something in practice, new SNiPs and GOSTs appear, according to which adjustments are made. Therefore, you should not try to learn all the documentation at once. It is enough to gain basic knowledge and add relevant data as you work.

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How to connect a generator

I didn’t want to connect the generator through the ATS circuit, because I don’t have the knowledge or funds for this, but I decided to do everything myself and connect it without automation.

The store advised me to connect the generator directly through the outlet, but I did not do so for safety reasons. And they offered and sold me this adapter:

Cable with plugs for connecting the generator to an outlet

To make using the generator safer, I made the following socket for it on the wall of the summer kitchen:

Generator socket

The SSI-114 type socket has a cover that protects live parts. But there will always be voltage on it - both when the generator is running and from the street! I secured it higher so that the children couldn’t reach it.

I made another adapter for connection so as not to confuse it with anything else, and signed the danger warnings.

Connection cable

The fork looks like this:

Generator output plug

This is the most dangerous place in the structure. But how to avoid trouble is the secret in the connection sequence, more on that later.

Introduction

For circuit designers, instrumentation mechanics, electricians, the ability to read an electrical diagram is a key quality and indicator of qualification. Without special knowledge, it is impossible to immediately understand the intricacies of designing devices, circuits and methods of connecting electrical units.

Symbols can be considered a special cryptographic code that explains the operation and principle of operation of a particular scheme. In Japan, the USA and Europe, icons differ significantly from domestic markings, which must be taken into account.

Types and types of electrical circuits

Before you begin to study the existing symbols of electrical equipment and its connections, you need to understand the typology of circuits. On the territory of our country, standardization has been introduced according to GOST 2.701-2008 dated July 1, 2009, according to “ESKD. Scheme. Types and types. General requirements".

1. United.
2. Located.
3. Are common.
4. Connections.
5. Installation connections.
6. Completely principled.
7. Functional.
8. Structural.

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

1. Combined.
2. Divisions.
3. Energy.
4. Optical.
5. Vacuum.
6. Kinematic.
7. Gas.
8. Pneumatic.
9. Hydraulic.
10. Electrical.

For electricians, it is of greatest interest among all the above types and types of circuits, as well as the most popular and often used in work - an electrical circuit.

The latest GOST, which came out, has been supplemented with many new designations, current today with code 2.702-2011 dated January 1, 2012. The document is called “ESKD. Rules for the execution of electrical circuits” refers to other GOSTs, including the one mentioned above.

The text of the standard sets out clear requirements in detail for electrical circuits of all types. Therefore, when performing installation work with electrical circuits, this document should be used as a guide. The definition of the concept of an electrical circuit, according to GOST 2.702-2011, is as follows:

“An electrical diagram should be understood as a document containing symbols of parts of a product and/or individual parts with a description of the relationship between them and the principles of operation from electrical energy.”

Once defined, the document contains rules for the implementation on paper and in software environments of contact connection designations, wire markings, letter designations and graphic representations of electrical elements.

It should be noted that most often only three types of electrical circuits are used in home practice:

• Mounting - for the device, a printed circuit board is shown with the arrangement of elements with a clear indication of the location, rating, principle of fastening and connection to other parts. Electrical wiring diagrams for residential premises indicate the number, location, rating, connection method and other precise instructions for the installation of wires, switches, lamps, sockets, etc.
• Fundamental - they indicate in detail the connections, contacts and characteristics of each element for networks or devices. There are complete and linear circuit diagrams. In the first case, control, control of elements and the power circuit itself are depicted; in a linear diagram, they are limited only to the circuit with the remaining elements depicted on separate sheets.
• Functional - here, without detailing the physical dimensions and other parameters, the main components of the device or circuit are indicated. Any part can be depicted as a block with a letter designation, supplemented by connections with other elements of the device.

Switch ABB SD200.

The SD200 series switches are relatively new, and they began to be produced in 2022. Outwardly, they are almost indistinguishable from the old copy of the E200 series.

But this is only external. Many people know that the E200 series had a design jamb, and therefore they were replaced with a new series.

As the name of the SD200 series suggests, the ABB switch, like the S200 circuit breaker, depending on the last digit, is divided by the number of poles:

• SD201 - single pole,
• SD202 - two-pole,
• SD203 - three-pole,
• SD204 - four-pole.

The photo also shows an example of a 2-pole switch. Such switches SD201 and SD202 are convenient to use in single-phase switchboards, because they take up less space than OT63, which will take up at least 3 modules.

The ABB SD200 switch is available in rated currents: 16, 25, 32, 40, 50 and 63A. All additional contacts intended for the ABB module are suitable for it.

Graphic symbols in electrical diagrams

• 2.755-87 – graphic symbols of contact and switching connections.
• 2.721-74 – graphic symbols of parts and assemblies for general use.
• 2.709-89 – graphic symbols in electrical diagrams of sections of circuits, equipment, contact connections of wires, electrical elements.

In the standard with code 2.755-87, it is used for diagrams of single-line electrical panels, conventional graphic images (CGI) of thermal relays, contactors, switches, circuit breakers, and other switching equipment. There is no designation in the standards for automatic devices and RCDs.

On the pages of GOST 2.702-2011, it is allowed to depict these elements in any order, with explanations, decoding of the UGO and the circuit diagram of the difavtomat and RCD itself. GOST 2.721-74 contains UGOs used for secondary electrical circuits.

IMPORTANT: To designate switching equipment there is:

4 basic UGO images

9 functional signs of UGO

IMPORTANT: Designations 1 – 3 and 6 – 9 are applied to the fixed contacts, 4 and 5 are placed on the moving contacts.

Basic UGO for single-line diagrams of electrical panels

• Pin
• Nest

Read also: Laser diode connection diagram

Changeover switch principle of operation

An electrical type device that serves to disconnect an electrical load from one energy source and connect it to another source is called a changeover switch, or a changeover type switch (switch with a midpoint). The devices are available with or without arc arresters. In the first case, network switching can occur with a fully connected load. In the second - only when it is turned off.

The switch is operated manually, that is, if it is necessary to switch power sources, the operator acts on the isolated control lever of the switch. There are also automatic switching systems.

Designation of measuring electrical instruments to characterize circuit parameters

GOST 2.271-74 accepts the following designations in electrical panels for buses and wires:

Letter designations in electrical diagrams

The standards for the letter designation of elements on electrical circuits are described in the GOST 2.710-81 standard with the text title “ESKD. Alphanumeric designations in electrical circuits." The mark for automatic devices and RCDs is not indicated here, which is prescribed in clause 2.2.12 of this standard as a designation with multi-letter codes. The following letter codings are accepted for the main elements of electrical panels:

Representation of electrical equipment on plans

Despite the fact that GOST 2.702-2011 and GOST 2.701-2008 take into account this type of electrical circuit as a “layout diagram” for the design of structures and buildings, one must be guided by the standards of GOST 21.210-2014, which indicate “SPDS.

Images on the plans of conventional graphic wiring and electrical equipment.” The document establishes UGO on plans for laying electrical networks of electrical equipment (lamps, switches, sockets, electrical panels, transformers), cable lines, busbars, tires.

The use of these symbols is used to draw up drawings of electric lighting, power electrical equipment, power supply and other plans. The use of these designations is also used in basic single-line diagrams of electrical panels.

Conventional graphic images of electrical equipment, electrical devices and electrical receivers

The contours of all depicted devices, depending on the information richness and complexity of the configuration, are taken in accordance with GOST 2.302 on the scale of the drawing according to the actual dimensions.

Conventional graphic designations of wiring lines and conductors

Conventional graphic images of tires and busbars

IMPORTANT: The design position of the busbar must exactly coincide on the diagram with the place of its attachment.

Conventional graphic images of boxes, cabinets, panels and consoles

Conventional graphic symbols of switches, switches

On the pages of documentation GOST 21.210-2014 there is no separate designation for push-button switches, dimmers (dimmers). In some schemes, according to clause 4.7. the normative act uses arbitrary designations.

Conventional graphic symbols of plug sockets

Conventional graphic symbols of lamps and spotlights

The updated version of GOST contains images of lamps with fluorescent and LED lamps.

Conventional graphic symbols of monitoring and control devices

Single pole switches

In many cases, devices with only one module are used .
In such modifications, copper conductors. It is important to know that they should be used to service generators whose operating frequency range is not higher than 20 Hz. There are also certain disadvantages that are taken into account when choosing. An important nuance: the maximum load during use should not exceed 200 A. Therefore, they are not installed in residential buildings where there is significant electricity consumption. Another feature: low output voltage, mostly 200 V.