Types of markings on diagrams and equipment, item designations

In electrical circuits, marking is very important, without which they are practically unreadable. The circuit designation system in the diagrams must comply with GOST 2.709-72.

For an electrical installation of circuits of all types, the same elements and sections of electrical circuits are designated in the same way. In the event of a disagreement due to an error in the marking, the marking indicated on the circuit diagram is considered the main one. Marking is carried out both on the drawings and on the corresponding apparatus and devices.

On schematic diagrams, the mark is placed above the wire section, and with the vertical arrangement of the chain - to the right of it.

The types and order of markings are as follows:

1) factory marking of devices and products (for example, see — Marking of household fluorescent lamps, Marking of the power cable);

2) marking of terminals of electrical machines and devices (unified);

For example, the conclusions of the windings of three-phase machines with current are indicated in accordance with GOST 26772 — 85.

Table 1. Marking of terminals of three-phase machines

Name and connection scheme of the windings Number of pins The name of the conclusions Pin designation Start End Stator windings (armature). Open circuit 6 First phase

Second phase

Third phase

U1 (C1)

V1 (C2)

W1 (C3)

U2 (C4)

V2 (C5)

W2 (C6)

Star Link 3 or 4 Phase One

Second phase

Third phase

Neutral

U (C1)

V (C2)

W (C3)

N (0)

Delta connection First clamp

Second bracket

Third bracket

U (C1)

V (C2)

W (C3)

Exciting coils (inductors) of synchronous machines 2 F1 (And1) F2 (And 2)

3) reference designations. Each element of the electrical circuit must have a designation, which is the abbreviated name of the element and may reflect the functional purpose of the element. For example, time relay — KT1, KT2, automatic switch — QF1, etc. (see — Tables 2 and 3);

4) marking of sections of electrical circuits. Each section of the circuit between two circuit elements must be marked. The stamp can be digital or alphanumeric. The marking is built according to the principles of coordinates and addresses in the form of a sweep or in a row from left to right (for more details see here — Designation of electrical circuits in diagrams);

5) the marking of the circuit of the terminals of the apparatus is determined by the brand of the connected wire and may not coincide with the factory marking at the place of the output of the apparatus;

6) factory marking of the places of the outputs of circuits of electrical equipment;

7) address marking, which is usually indicated on connection diagrams and indicates to which device or circuit element this circuit is connected;

8) numbering the chains in order (from top to bottom). This notation makes it easy to describe the circuit by allowing you to make text references to the net numbers and find them quickly;

9) numbering of sections — the same as for separate circuits, but with a combination of several circuits in one block.

Positional designations on electrical diagrams

The alphanumeric designations of the electrical diagrams must match GOST 2.710-81

Table 2. Positional designations of the elements of the diagrams. Letter codes of the most common elements

First letter of the code (required) Item view group Examples of item types A Devices Amplifiers, remote control devices, lasers, masers V Converters of non-electric quantities to electrical quantities (other than generators and power supplies) or vice versa Analog or multi-digit converters or sensors for indication or measurement Loudspeakers, microphones, thermoelectric sensing elements, ionizing radiation detectors, pickups, selsins C Capacitors — e Integrated circuits, micro-assemblies Analog digital integrated circuits, logic elements, memory devices, delay devices E Elements are various Illumination devices, heating elements F Arresters, fuses, protection devices Discrete current and voltage protection elements, fuses, limiters G Generators, power supplies, quartz oscillators Batteries, accumulators, electrochemical and electrothermal sources З Indicator and signaling devices Sound and light alarm devices, indicators YES CE Relays, contactors, starters Current and voltage relays, electric thermal relays, time relays, contactors, magnetic starters L Inductors, chokes Fluorescent light chokes M DC and AC motors R Instruments, measuring equipment Indicating, recording and measuring devices, counters , watches B Switches and disconnectors in power circuits Disconnectors, short circuits, circuit breakers (power supply) R Resistors Variable resistors, potentiometers, varistors, thermistors C Switching devices in control, signal and measurement circuits Switches, switches, switches operated by various influences T Transformers, autotransformers Current and voltage transformers, stabilizers U Electrical quantity converters, communication devices Modulators, demodulators, discriminators, inverters, frequency converters, rectifiers V Electrovacuum and semiconductor devices Electronic lamps, diodes, transistors, thyristors, zener diodes W Microwave lines and elements , antennas Waveguides, dipoles, antennas x Contact connections Pins, contacts, decoupling joints, collectors Y Mechanical devices with electromagnetic drive Electromagnetic clutches, brakes, chucks Z Terminal devices, filters, limiters Modeling lines, quartz filters

Table 3. Examples of two-letter codes most commonly found in electrical circuits

First code letter (required) Element view group Examples of element types Two-letter code B Converters of non-electric quantities to electrical quantities (other than generators and power supplies) or vice versa Analog or multi-digit converters or sensors for indication or measurement Thermosensor BK Photocell BL Sensor for pressure BP Speed ​​sensor (tachogenerator) BR Speed ​​sensor BV E Elements are different Heating element EK Lighting lamp EL F Arrests, fuses, protective devices Fuse with fuse FU G Generators, power supplies Battery GB З Indicator and signaling elements Audible alarm device ХА Light signaling device HL К Relays, contactors, starters Relay current KA Electric thermal relay КК Contactor, magnetic starter KM Time relay KT Voltage relay KV С Switching devices in control, signal and measurement circuits. Note. The designation SF is used for devices without power circuit contacts. Switching or switching SA Push-button switch SB Automatic switching SF Switches actuated by various influences: — by level SL — by pressure SP — by position (track) SQ — by rotation frequency SR — by temperature SK In Switches and disconnectors in power circuits Automatic switching QF