Marking of domestic and imported electric motors: decoding of symbols

In the era of the USSR, the presence of standard markings on any electric motors, uniform throughout the state, significantly facilitated the work of electricians.

All significant information was displayed on a special nameplate. According to those rules, asynchronous electric motors produced in the USSR were designated A, A2, AO2, 4A, 4AM.

If the engines originated from the countries of the Union bloc, had a similar appearance, perhaps 4A changed its designation to MO, and 4AM was designated as M.

But after the collapse of the Union, there was no single service responsible for standardizing such details, which creates trouble for modern craftsmen when carrying out service work.

Let's try to understand the issue.

Designation of asynchronous electric motors

Let’s say the nameplate says AO2-62-4. The first two letters (or letter) are the execution of the engine:

• A – splash-proof.
• AO – closed ventilated.

The number following the letters means the series number (in our case 2). The two-digit number after the first dash is the standard size (6 is the outer core of the stator diameter, 2 is the length; both designations are conventional). The number after the second dash indicates the number of poles. That is, in our case we are dealing with a four-pole asynchronous three-phase motor of the second series in a closed, ventilated design, of the second length, of the sixth size.

Machines from 1 to 5 sizes of this series are considered more reliable and durable than engines in a protected design. A number of modified models are manufactured based on engines of the A, A2, AO and AO2 series. A 2nd (or 3rd) letter is added to their markings:

• P – overestimated starting torque.
• C – increased slip.
• K – model with a wound rotor.
• T – for use in the textile industry.
• L – shields and body are made of duralumin alloy.

General purpose motors with a duralumin stator winding are designated by the letter A after the last digit. The numbers divided by oblique lines (12/8/6/4) show the number of poles if the unit is designed for several speeds.

The following designations for asynchronous electric motors are also possible: 4AN280M2UZ. Deciphering the markings in order, we get the following:

• Series number – 4.
• Motor type – asynchronous protected – AN. If there is no letter H, the engine is a closed, ventilated design.
• The height of the rotation axis is 280 (it can be indicated by two numbers).
• The installation dimension along the length of the bed is M (S and L are possible).
• Number of poles – 2.
• Climatic version - U.
• Accommodation category – 3 (digital).

The letters A or X after the first A (AA or AX) indicate duralumin panels and a frame in the first case, and cast iron panels and a duralumin frame in the second. The letter K in the fourth position (4ANK) marks motors with a wound rotor.

The stator core can be of different lengths with unchanged frame dimensions. The sign A denotes the shortest, and the sign B the greatest length of the core. These letters are placed after the rotation height marking.

Import standard

Imported products are labeled in a similar way. The sample shows an Italian engine, marked according to European regulations. It is not difficult to find a domestic analogue.

The Siemens company offers a wide range of electric motors.

The nameplate contains indicators for standard power supply, but its frequency is taken into account. Below is an illustration explaining this feature.

The Chinese manufacturer completely copies the German standard.

It may be difficult to identify parameters due to the loss of the information plate. There is no point in despair, since there are several reliable ways to determine the parameters of electric motors.

• Based on the length and diameter of the shaft, using tabular data, the standard power is obtained.
• Selection is based on landing dimensions. And again use the tables that are given below.
• The resistance of the windings is measured, then the power is obtained using the standard formula (Ohm's law). In this case, a star connection is used for measurements, and the total is divided by 2. The resulting value is substituted into the formula P = (. 220v * 220v)/R, and the result obtained is multiplied by 3 - the result is the power. If we have a triangle, then we replace the factor three with six.
• Start the engine after connecting the ammeter. And, having learned the current at idle, they select an analogue.

The situation of losing a plate is almost typical in production, so the electrician must master the skill of selecting a replacement.

It is also important to remember that in many situations it is extremely important to take into account the direction of rotation of the motor (fan, pump, machine drive, etc.).

Moreover, this point should be observed for both single-phase and three-phase machines. Often the direction is indicated by an arrow on the frame.

Engine marking according to climatic design

There is a generally accepted marking of the climatic performance of the engine:

• Temperate climate - U.
• Cool climate - HL.
• Humid tropical climate - TV.
• Dry tropical climate - TC.
• Tropical climates of both types - T.
• General climatic design (any land area) – O.
• Cool temperate maritime climate - M.
• Marine tropical climate - TM.
• Unlimited navigation area - OM.
• Any areas at sea and on land - V.

Electric motor AIR characteristics

X

Engine marking by placement category

For marking by accommodation category, numbers from 1 to 5 are used, where:

• 1 - work outdoors.
• 2 – work under a canopy or in a room with free air circulation.
• 3 – work indoors with significantly less fluctuations in humidity and temperature than outside, as well as with minimal exposure to dust and sand.
• 4 – work in a closed, ventilated and heated room (with controlled climatic conditions).
• 5 – work in a damp room (underground, with prolonged presence of water and fumes, with possible frequent condensation).

Marking of drives of radio-controlled models

Brushless model motors are a separate case. There are two fundamental parameters here - the size of the stator and the external dimensions (diameter or height).

Marking of four numbers, the first pair of which indicates the height/diameter, and the next pair indicates the stator size in mm. Example: 2212.

It is important to remember that it is the stator size that is taken into account. But for this reason its external dimensions will differ from 22 mm and 12 mm. True, with the same stator, its winding may turn out to be different.

This is a brief overview of the problem that we hope will help our readers figure out for themselves a very common problem.

Marking of engines by degree of protection

The degree of protection implies the exclusion of the possibility of solid bodies and drops of water getting into the mechanism and human contact with moving and conductive components. Electric motors in a protected design are designated by numbers and letters - 1P23 or IP22. Enclosed units are marked IP44.

Knowing the decoding of the markings of asynchronous electric motors, you will be able to select a model that is optimally suited for operation in the given conditions and meets environmental and technical safety requirements.

Connection diagram and decoding of terminal designations in the box

The electric motor has a terminal box, it is also called “Brno”. Where the terminals of the beginning and end of the stator windings are bolted.

The above figure shows a box with terminal markings, and the figure below shows the designation of the winding terminals, by bridging which in a certain way, you can get a delta or star connection:

• U1 is the end of the first winding, and W2 is the beginning of the third;
• V1 is the end of the second, and U2 is the beginning of the first;
• W1 is the end of the third, and V2 is the beginning of the second.

By bridging contacts U1, V1, W1 we get a star connection of the windings, and by bridging pairs of contacts U1 with W2, V1 with U2, W1 with V2 we get windings connected with a triangle.

Possible built-in options for SIEMENS electric motors

TABLE 2.

Note: If difficulties arise with the optimal selection of Siemens electric motors, the specialists of the Techprivod Trading House will provide you with qualified assistance.

Pickup

The goods can be received on weekdays at a warehouse in Moscow, St. Petersburg or Rostov-on-Don. Shipment time is 1-3 days after payment. The order must be pre-agreed with the manager of TECHPRIVOD ENGINEERING.

Delivery in Moscow

For orders over RUB 100,000. Delivery within Moscow is free.

Regions of Russia

The order can be delivered to any region of Russia. Delivery is carried out by transport or carrier chosen by the customer. The goods are delivered to the transport company terminal free of charge. The approximate cost of delivery can be calculated using a tariff calculator.

To clarify delivery conditions and ask additional questions, please call: +7

and
8
(free call).

Design features

From a technical point of view, the AIR electric motor is one of the types of asynchronous electric machines. This variety first came into use back in 1973 and replaced the 4A and AM brands thanks to a new international standard that established its parameters and technical features. A structural example of asynchronous electric motors is shown in the figure below:

Rice. 1. Design of the AIR electric motor

As you can see, the AIR engine consists of the following main structural elements:

• Housing - made of cast iron or lightweight alloys, designed to hold internal parts and fasten to the working surface.
• Stator magnetic circuit - used as a medium for conducting magnetic flux from the windings to the rotor.
• Stator windings are made of copper conductors with varnish insulation, as a rule, they have an additional layer. Designed for the flow of alternating current, which generates electromagnetic waves. The winding wires are laid in the stator grooves.
• The rotor is phase or short-circuited; the phase rotor consists of a metal shaft on which there is a squirrel cage and windings placed in its grooves. The squirrel-cage rotor is a monolithic block made of ferromagnetic material. The rotor is designed to rotate inside the electric motor due to the influence of electromagnetic forces.
• Borna - the terminal box is designed to connect the electrical power cable, allowing you to change the connection diagram of the windings.

Electric motor connection diagram

Nominal data are given in accordance with GOST 28173-89.

AIR electric motors designed for a voltage of 220/380V must be connected when the windings are connected in a star to a linear voltage of 380V, and when the windings are connected in a delta to a linear voltage of 220V.

Similarly, AIR electric motors designed for a voltage of 380/660V must be connected when the windings are connected in a “star” to a linear voltage of 660V, and when the windings are connected in a “delta” to a linear voltage of 380V.

For electric motors designed for a voltage of 380V, the windings are by default connected in a “star” for a linear voltage of 380V.

A different connection of the windings will lead to failure of the electric motor and the manufacturer’s refusal of warranty obligations due to the presence of “consumer fault”.