Glossary

An alternating current motor (AC motor) is an electrical machine that converts electrical energy from an AC power supply into mechanical energy (usually in the form of rotational motion). It is one of the most commonly used drives in industry, commerce, and households and is characterized by robustness, longevity, and comparatively low maintenance requirements.

The operating principle is based on electromagnetic induction: when the stator (the stationary part of the motor) is supplied with alternating current, a time-varying magnetic field is generated. In the case of polyphase AC – especially the common three-phase current – a rotating magnetic field, also called a revolving field, is formed. This rotating field acts on the rotor (the moving part of the motor) and sets it into rotational motion.

The detailed functionality relies on the generation of this rotating field in the stator. In a three-phase motor, three alternating currents, each phase-shifted by 120°, flow through the stator windings. This creates a magnetic field of constant magnitude, which rotates at the so-called synchronous speed. This speed depends on the frequency of the applied AC and the number of pole pairs of the motor.

There are mainly two types of AC motors:

• Asynchronous Motor (Induction Motor):
In this type, a voltage is induced in the rotor by the rotating magnetic field of the stator. This generates a current in the rotor, which in turn produces its own magnetic field. The interaction between the stator and rotor fields generates the torque. For this effect to occur, a relative motion is required – therefore, the rotor always runs slightly slower than the rotating field. This difference is called slip. Asynchronous motors are particularly robust, cost-effective, and widely used.

• Synchronous Motor:
In a synchronous motor, the rotor has its own constant magnetic field, generated either by permanent magnets or a DC excitation. This field couples with the rotating magnetic field of the stator and rotates exactly at its speed. In steady-state operation, no slip occurs, resulting in a very constant speed. Synchronous motors offer high efficiency and precise controllability.

The speed of an AC motor essentially depends on the supply frequency and the number of pole pairs. In modern applications, frequency converters are often used to control the speed continuously and adapt it to different requirements.

The main advantages of AC motors include their simple and robust construction, long service life, and high operational reliability. They are particularly suitable for applications with medium to high power. Disadvantages may include more complex speed control and specific requirements during the startup of certain designs, although modern power electronics have largely optimized these aspects.

Typical applications include electric drives in production facilities, pumps, fans, compressors, conveyor systems, as well as numerous household appliances such as washing machines or air conditioning units. Due to their versatility and cost-effectiveness, AC motors are a central component of modern electrical engineering.

ATEX (2014/34/EU) is an EU directive that sets requirements for equipment and protective systems intended for use in explosive atmospheres. “ATEX” originates from the French term “Atmosphères Explosibles.” Its aim is to ensure the safety of people, the environment, and property, while also enabling the free movement of goods within the EU.

Equipment Categories
The directive divides equipment into three main categories, defining the required safety level depending on the frequency and duration of the presence of an explosive atmosphere:

• Category 1: Highest safety level, suitable for areas with continuous or frequent explosion hazards. Equipment in this category must remain safe even in the event of protective system failures.
• Category 2: For areas with occasional explosion hazards. Equipment must provide a high level of safety and operate safely for a certain period even in case of malfunctions.
• Category 3: For areas with rare or short-term explosion hazards. Equipment must ensure safe normal operation without requiring extreme safety measures.

Zone Classification
Explosive atmospheres are classified into zones to assess the risk:

• Zone 0 (Gases) / Zone 20 (Dusts): Continuous or very frequent presence of an explosive atmosphere.
• Zone 1 (Gases) / Zone 21 (Dusts): Explosive atmosphere occurs occasionally under normal conditions.
• Zone 2 (Gases) / Zone 22 (Dusts): Explosive atmosphere occurs rarely or only for a short period.

The assignment of equipment category and zone is crucial to select the appropriate protection level for equipment. Additionally, ATEX markings provide information about the type of explosion (gas, vapor, mist, or dust) and the temperature class, which indicates the maximum surface temperature of the device to prevent ignition.

ATEX (2014/34/EU) is thus a central component of European explosion protection, defining uniform safety standards for manufacturers, operators, and users.

Certifications are official proofs that a product, such as an electric motor or a machine, complies with international standards, safety requirements, and legal regulations. They serve to ensure safety, quality, and reliability, as well as acceptance in national and international markets.

Function:
• Certifications confirm that equipment has been tested and verified, for example with regard to electrical safety, explosion protection, electromagnetic compatibility (EMC), thermal stress, or mechanical stability.
• Manufacturers must provide appropriate tests, inspections, and documentation before a certificate is issued.
• Certifications enable operators to select safe and compliant products and ensure adherence to legal requirements.

Examples of relevant certifications in the motor sector:
• ISO 9001: Quality management and process reliability
• ATEX / IECEx: Explosion-protected equipment for hazardous areas
• CSA / UL: North American safety and performance standards
• EAC: Conformity for the Eurasian Economic Area

Certifications are therefore a key component of product quality, operational safety, and international marketability. They provide manufacturers, planners, and users with confidence that a product can be operated safely, reliably, and in compliance with applicable standards.

Compensating windings are additional windings in DC motors that are arranged above the main pole windings. They counteract the effects of armature reaction, which can otherwise lead to torque reduction or uneven operation in motors without compensating windings.

Function:
• Reduction of voltage fluctuations in the armature current
• Stabilization of torque during load changes
• Improvement of smooth operation and operational reliability

Applications:
• Test benches where motors must withstand rapid load changes
• Cranes and hoisting equipment that move varying loads
• Production machines with dynamic operating cycles

By adding auxiliary windings to the main windings, compensating windings make a significant contribution to the performance, stability, and reliability of DC motors, especially in applications with dynamic loads and frequent acceleration or deceleration.

Cooling Methods
IC cooling describes standardized methods for heat dissipation in electric motors according to the standards of the International Electrotechnical Commission (IEC). It ensures that the temperature within the motor is limited in order to prevent overheating, performance losses, and premature wear. Effective cooling increases the service life of the motor and enables reliable continuous operation under varying load conditions.

Typical IC cooling methods:
• IC 01: Protection class IP21 – IP23 (Type G...): Self-ventilated internal cooling – Cooling air is blown through the motor by a fan mounted on the rotor.

• IC 06: Protection class IP21 – IP23 (Type G..I): Forced internal cooling – Cooling air is blown through the motor by an external fan. The intake side can be equipped with a dust filter.

• IC 17: Protection class IP21 – IP23 (Type G..): Pipe connection for forced internal cooling – Cooling air is supplied through a pipe connection by a separate external fan provided by the customer and exits into the open space on the opposite side.

• IC 410: Protection class IP44 – IP55 (Type G..ZE): Self-ventilated surface cooling – Cooling air is blown over the closed motor surface by a fan mounted on the rotor.

• IC 416: Protection class IP44 – IP55 (Type G..ZO): Forced surface cooling – Cooling air is blown over the closed motor surface by an external fan.

• IC 37: Protection class IP44 – IP55 (Type G..Z): Two pipe connections for forced internal cooling – Cooling air is supplied through one pipe connection by a separate external fan provided by the customer and exits through another pipe connection on the opposite side of the motor.

The selection of the appropriate IC cooling method depends on motor power, installation environment, load profile, and ambient temperature. Insufficient cooling can lead to overheating, insulation problems, and reduced efficiency, while optimized IC cooling maximizes motor performance, efficiency, and service life.

CSA / UL refer to safety certifications for electrical devices, components, and industrial equipment that ensure safe operation according to national and international standards.

• CSA (Canadian Standards Association):
The CSA is a Canadian standards and certification organization. Products carrying the CSA mark meet the applicable safety requirements for Canada and, in some cases, also for the USA. Certification includes testing, conformity assessment, and regular production inspections. It covers electrical safety, fire and explosion protection, mechanical safety, and other relevant aspects.

• UL (Underwriters Laboratories):
UL is a U.S.-based testing organization that develops safety standards and evaluates compliance. Devices bearing a UL mark have been tested for electrical safety, fire and explosion risks, as well as mechanical hazards. UL certifications are recognized worldwide and facilitate market access in North America.

Both certifications play a central role in the market approval and safety of electrical equipment, particularly for industrial applications, mechanical engineering, household appliances, and components in explosive atmospheres. CSA and UL testing is often conducted in parallel, as they each cover local regulations in Canada and the USA.

They are especially important for the export of electric motors to the USA and Canada.

A direct current motor (DC motor) is an electrical machine that converts electrical energy into mechanical rotational motion and operates on direct current. DC motors are primarily used where precise control of speed and torque is required, e.g., in power tools, conveyor systems, robotics, or vehicle drives.

The operating principle is based on the interaction between a magnetic field and a current-carrying conductor: the stator generates a constant magnetic field (using permanent magnets or separate field windings), while the rotor (armature) is supplied with direct current. Torque is generated through the Lorentz force, which sets the rotor in motion.

DC motors are mainly classified according to the type of field winding:

• Series Wound Motor: Field and armature windings are connected in series. Provides high starting torque, speed depends on load, used, for example, in electric vehicles or machine tools.

• Shunt Wound Motor: Field winding is connected in parallel to the armature. Offers nearly constant speed under varying load, e.g., for conveyor belts or fans.

• Compound Motor (Series-Shunt Motor): Combination of series and shunt windings. Combines the advantages of both types: good starting torque and relatively constant speed under load. Commonly used in machine tools or hoisting equipment.

• Permanent Magnet DC Motors: Use permanent magnets for the stator field. Compact, low-maintenance, and efficient.

DC motors allow simple and precise speed control, as the speed can be directly influenced by the applied voltage or current control. Disadvantages include generally higher maintenance for brushed motors and a more complex construction compared to asynchronous AC motors.

DC motors are particularly suitable for applications where speed, acceleration, and load behavior must be precisely controlled.

EAC certification is a conformity assessment for the Eurasian Economic Union (EAEU), which includes countries such as Russia, Kazakhstan, Belarus, Armenia, and Kyrgyzstan. It certifies that electrical devices, machines, and systems comply with the applicable technical regulations and safety standards in these regions.

Manufacturers must have their products tested, demonstrate compliance with all relevant standards, and issue a declaration of conformity. The assessment includes electrical safety, mechanical strength, electromagnetic compatibility (EMC), as well as specific requirements for operation in the respective countries.

The EAC marking on products indicates that they are legally approved and facilitates market access within the Eurasian Economic Union. It also serves as a reference for users and operators that the equipment can be operated safely and in accordance with applicable standards.

The efficiency of a motor or drive describes the ratio between the mechanical output power and the electrical input power. It indicates how efficiently electrical energy is converted into motion.

                                                                                               η = P_mechanical / P_electrical * 100%

with:

• η: efficiency 
• P : power in kilowatts (kW)

A high efficiency means that only a small amount of energy is lost in the form of heat. This reduces operating costs, minimizes heat generation, and extends the service life of the motor. Factors that influence efficiency include motor design, material quality, load, rotational speed, and cooling.

In practice, efficiency is particularly important for continuous operation, high power demand, or energy-efficient drive solutions. Motors with high efficiency contribute to energy savings and the reduction of environmental impact.

Ex motors are specifically designed for use in hazardous areas. Such areas may contain gas, vapor, mist, or dust atmospheres that could be ignited by sparks, overheating, or mechanical ignition sources. Ex motors prevent electrical or mechanical components from acting as ignition sources and enable safe operation in hazardous zones.

Key types of protection:
• “e” (Increased Safety): Components and connections are designed to prevent sparking and excessive heating.
• “d” (Flameproof Enclosure): Potential explosions inside the motor are safely contained so that the surrounding environment is not endangered.
• Other protection types (e.g., “t” for intrinsic safety, “p” for pressurized enclosure) are used depending on the application and ATEX/IECEx standards.

Applications: Ex motors are used in the chemical, petrochemical, food, wood, and pharmaceutical industries—wherever potentially explosive atmospheres may occur. They comply with ATEX (Europe) or IECEx standards (international) and are therefore essential for explosion protection in industrial systems.

Effect: Through appropriate design measures, materials, and enclosure types, Ex motors prevent sparks, high surface temperatures, or internal explosions from igniting the surrounding atmosphere, thereby making a crucial contribution to operational safety and personnel protection.

The type of protection defines the technical measures by which a device or motor can be safely operated in hazardous (potentially explosive) environments. It specifies how electrical and mechanical components must be designed so that sparks, overheating, or other potential ignition sources cannot trigger an explosion in the surrounding atmosphere.

Important types of protection:
• “e” (increased safety): Components and connections are designed to prevent the occurrence of sparks and excessive temperatures.
• “d” (flameproof enclosure): Possible explosions inside the housing are safely contained so that the external environment is not endangered.
• Other types: These include, for example, “t” (protection by enclosure), “p” (pressurized enclosure), and others, depending on the applicable standards (ATEX/IECEx) and the specific hazard.

Significance:
Selecting the correct type of protection is crucial to ensure explosion safety in systems with flammable gases, dusts, or vapors. It is an integral part of explosion protection measures and is used in conjunction with certifications such as ATEX or IECEx.

For further information, see the section on explosion protection.

The International Electrotechnical Commission (IEC) is a global standardization organization that develops international standards for electrical, electronic, and related technologies. Its goal is to ensure the safety, interoperability, efficiency, and reliability of electrical equipment and systems.

IEC standards cover a wide range of areas, including:
• Electric motors and generators
• Switchgear and control systems
• Types of protection, insulation materials, and climate classes
• Measurement technology, power electronics, and communication technology

For motors such as AC or DC motors, IEC 60034 defines, among other things, frame sizes, connection types, cooling methods (IC classes), degrees of protection (IP), and testing procedures. This standardization ensures the interchangeability and comparability of products on an international level, which is particularly important for global trade and industrial automation.

IEC standards are regularly updated to incorporate technological innovations, safety requirements, and environmental considerations. Companies that manufacture IEC-compliant products not only ensure quality and safety but also secure international recognition of their products.

Insulation classes define the maximum thermal endurance of the winding insulation in an electric motor. They specify the temperatures that the motor winding insulation can withstand continuously without damage. A higher insulation class allows safe operation at higher temperatures and extends the service life of the motor.

Typical insulation classes:
• Class A: up to 105 °C
• Class B: up to 130 °C
• Class F: up to 155 °C
• Class H: up to 180 °C

The selection of the appropriate insulation class depends on the load profile, ambient temperature, cooling, and duration of operation. In motors with high continuous loads, frequent load changes, or limited cooling, higher insulation classes are preferred to prevent overheating, insulation damage, and premature failure.

Insulation classes are internationally standardized according to IEC and form a fundamental basis for the design, evaluation, and comparability of electric motors.

The IP protection class describes the degree of protection of an electrical device or motor against the ingress of foreign objects (e.g., dust, dirt) and water. It is indicated by two digits:

• First digit (0–6): Protection against solid particles
• Second digit (0–9): Protection against water

Examples of typical protection classes for motors:
• IP44: Protection against solid foreign objects >1 mm and splashing water from all directions.
• IP54: Protection against harmful dust deposits and splashing water.
• IP55: Protection against dust and water jets.
• IP65: Dust-tight and protected against water jets.
• IP66 / IP67: Protection against powerful water jets or temporary immersion.

The correct IP protection class is crucial for the safe use of motors in dusty, humid, or demanding industrial environments. It influences service life, operational safety, and maintenance intervals of systems.

IP protection classes are standardized according to IEC 60529, ensuring a comparable and reliable classification—regardless of manufacturer or country of use.

NEMA MG1 is a U.S. standard developed by the National Electrical Manufacturers Association (NEMA) for electric motors. It defines mechanical dimensions, performance data, frame sizes, and connection types to ensure interchangeability and standardization of motors.

Purpose and Benefits:
• Ensures that motors from different manufacturers are mechanically and electrically compatible
• Provides uniform ratings for nominal power, nominal voltage, current, and frame size
• Facilitates planning, spare parts procurement, and installation

NEMA MG1 is primarily applied to industrial motors in North America but is also used worldwide as a reference. Standardization according to NEMA MG1 allows manufacturers, planners, and operators to easily compare and interchange motors without requiring individual modifications.

The overload capacity of an electric motor describes its ability to withstand higher currents or torque for short periods without sustaining damage. It is a key characteristic for applications in which load peaks or starting torques occur, such as when starting heavy machinery or under dynamic operating conditions.

Operating principle:
• Motors are capable of operating above their rated power for a limited period, as windings, bearings, and cooling systems are designed to tolerate short-term thermal and mechanical stresses.
• The duration and extent of overload capacity depend on the motor design, cooling method, insulation class, and speed range.
• Electronic control systems or motor protection devices monitor overload conditions and prevent permanent damage by shutting down or reducing power.

Sufficient overload capacity ensures that the motor starts reliably, handles load peaks, and responds dynamically to changing operating conditions without overheating or premature wear. It is a key factor for the service life, operational reliability, and efficiency of motors in industrial applications.

A permanent magnet motor is an electric motor in which the required magnetic field is generated by permanent magnets instead of electromagnetic field windings. This simplifies the construction, increases efficiency, and reduces energy consumption.

Operation:
• DC Motors:
In permanent magnet direct current (DC) motors, the magnetic field is provided by permanent magnets. The current flowing through the rotor windings (armature) generates an electromagnetic torque that interacts with the static magnetic field of the permanent magnets. Commutation (mechanically via brushes or electronically via a controller) controls the current direction so that the rotor rotates continuously.

• AC Motors / Synchronous Motors:
In permanent magnet synchronous motors, the stator supplies alternating current, creating a rotating magnetic field. The rotor, equipped with permanent magnets, is carried along by this field and rotates synchronously with the frequency of the stator field. Since the rotor field is constant, the speed can be precisely controlled, and a smooth torque is produced without commutation.

Characteristics:
• High efficiency due to the elimination of field current losses
• Compact design, as no additional field windings are required
• Precise speed and torque control
• Low maintenance, as AC synchronous motors do not require brushes

Applications:
Permanent magnet motors are used both as DC and AC synchronous motors, especially where precise speed control, fast response, and compact design are required. Typical applications include robotic drives, machine tools, servo systems, conveyor technology, and power tools.

The modular construction, also referred to as platform design, is a design principle used in electric motors and drive systems in which standardized components and assemblies can be flexibly combined. Standardized elements such as housings, bearings, windings, or cooling units form the basis, which can be adapted depending on performance requirements or functional variants.

This principle makes it possible to realize different motor variants economically and efficiently without requiring a complete redesign for each version. By combining pre-manufactured modules, delivery times can be shortened, production simplified, and maintenance as well as spare parts supply standardized. The platform design thus combines the advantages of standardization and flexibility and contributes significantly to cost-efficient and adaptable drive solutions.

Mechanical power describes the work performed by a motor per unit of time. It is a measure of how quickly energy is converted into mechanical motion and results from the interaction of torque and rotational speed.

General formula:

                                                                                               P = M * ω

Where P is the power, M is the torque, and ω is the angular velocity.

In practice, since rotational speed is usually given in revolutions per minute, the following converted formula is often used:

                                                                                               P = M * n / 9550

 

The constant 9550 arises from the conversion between angular velocity and rotational speed.

Quantities:
• P: Mechanical power in watts (W) or kilowatts (kW)
• M: Torque in newton-meters (Nm)
• n: Rotational speed in revolutions per minute (RPM / 1/min)
• ω: Angular velocity in radians per second (rad/s)

In electrical engineering, power is a central parameter for evaluating motors and drive systems. It indicates how much mechanical work a motor can deliver per unit of time and thus largely determines the performance capability of a system.

For example, a motor can provide high torque at low speed or lower torque at high speed – in both cases, the delivered power can be the same. This shows that torque and speed are distinct quantities but together determine the power.

In real applications, a distinction is often made between the electrical input power and the mechanical output power. Due to losses such as friction, heat generation, or electrical resistance, the output power is always lower than the input power. The ratio of these two values is described by the efficiency.

Power plays a crucial role in drive design, as it determines whether a motor is capable of reliably performing a specific task, such as driving machinery, lifting loads, or accelerating vehicles.

The pump characteristic curve describes the operating behavior of a pump as a function of flow rate, head, pressure, and rotational speed. It shows how the delivery performance changes under different operating conditions and enables the optimal design of the pump for energy-efficient operation. Typically, the pump characteristic curve is presented as a diagram illustrating the relationship between volume flow and head.

The motor characteristic curve represents the performance data of an electric motor as a function of speed, torque, and current consumption. It shows how torque, power consumption, and mechanical output change under varying operating conditions. By understanding the motor characteristic curve, the motor can be optimally matched to the load requirements, preventing overload and ensuring efficient operation.

Interaction:
The combination of pump and motor characteristic curves is crucial for the energy-efficient and stable design of drive systems. By matching the curves, the pump can be operated precisely in the range where the motor works efficiently, while avoiding overload and inefficient operating conditions.

Rotational speed (RPM – revolutions per minute) refers to the number of revolutions of a rotating body per unit of time and indicates how fast a rotor, shaft, or motor operates.

Units:

• Revolutions per minute (rpm, RPM – revolutions per minute) 
• Hertz (Hz), with: 1 Hz = 1 revolution per second 

There is a direct relationship between rotational speed n and angular velocity w:

                                                                                                ω = 2π * n

Where ω is the angular velocity in rad/s and n is the rotational speed in 1/s (when given in rpm, conversion is done by dividing by 60).

In electrical engineering, rotational speed is a key characteristic of motors, as together with torque it determines the mechanical power. From this, rotational speed can also be calculated using power and torque:

                                                                                                n = P * 9550 / M

with:

• n: rotational speed in revolutions per minute (rpm) 
• P : power in kilowatts (kW) 
• M : torque in newton-meters (Nm) 

Distinctions for motors:

• No-load speed: Speed without load 
• Rated speed (operating speed): Speed under defined load conditions 
• Maximum speed: Maximum speed that can be reached briefly without damage 

Rotational speed in AC motors depends on the supply frequency and the number of pole pairs, while in DC motors it is influenced by the applied voltage and current. Precise control of rotational speed is essential for applications such as conveyor systems, machine tools, fans, or vehicle drives.

Starting resistors are used in electrical drives to limit the starting current of a motor and to enable a smooth ramp-up. When a motor starts, the current can temporarily become very high without any measures, which puts a heavy load on the power supply, the motor, and the mechanical load.

By using a starting resistor, the voltage applied to the motor is reduced, which decreases the current flow and simultaneously allows the starting torque to be controlled. In three-phase motors, the resistor is often connected in series with the stator windings, while in DC motors it is connected in series with the armature. During the start-up phase, the resistor is reduced stepwise or continuously until the motor receives the full operating voltage. This allows the motor to accelerate in a controlled manner without overloading the electrical or mechanical components.

Starting resistors are mainly used with larger motors, for example in conveyor systems, pumps, compressors, or machines where a smooth start is necessary. The sizing of the resistor must be carried out carefully, because a resistor that is too high will significantly reduce the current, but at the same time also reduce the starting torque. This could prevent the motor from starting the load under certain conditions.

Through the targeted use of starting resistors, the starting current can be significantly reduced, the starting torque can be optimally controlled, and the entire drive system can be operated more efficiently and gently.

Torque refers to the rotational force that produces rotation around an axis. It is a measure of how strongly a force can set a component or rotor into motion. Torque is calculated as the product of the force applied to a lever arm and the distance r between the point of force application and the axis of rotation:

                                                                                                  M = F * r
 

For electric motors, torque can also be determined from power and rotational speed. The formula is:

                                                                                                 M = P * 9550 / n
 

The constant 9550 results from the conversion between power, angular velocity, and rotational speed:

                                                                                                 9550 = 60 / 2π * 1000
 

Where:

• P is the power in kilowatts (kW), 
• n is the rotational speed in revolutions per minute (rpm), 
• M is the torque in newton-meters (Nm). 

In electrical engineering, torque is a central characteristic of motors, as it determines how much load a motor can move or accelerate. It depends on the motor design, current, voltage, and magnetic field.

Key types of torque include:

• Starting Torque: The torque a motor generates during start-up. 
• Rated Torque: The torque a motor can continuously deliver under rated conditions. 
• Maximum Torque: The highest torque the motor can produce briefly before being overloaded. 

Torque is closely related to rotational speed: in DC motors, torque can be controlled proportionally to the armature current, while in asynchronous AC motors, torque depends on slip.

High torque is critical for applications that require acceleration, load handling, or overcoming friction and inertia, e.g., in vehicle drives, machine tools, or hoisting equipment.

Vibration severity B is an industry standard used to evaluate the permissible vibration levels of electric motors and rotating machines. It indicates how much a motor may vibrate during operation without causing damage to bearings, shafts, or housings. Motors with low vibration severity generate less mechanical stress, run more smoothly, and have a longer service life.

Vibration severity classification:
• Vibration severity A: Classifies motors with normal vibration levels, typically standard motors with common tolerances.
• Vibration severity B: Represents reduced vibration levels and is considered a higher-quality classification. Class B motors are subject to stricter requirements regarding imbalance, balancing, and manufacturing quality in order to minimize stress on sensitive components.

Significance:
Choosing the appropriate vibration severity is particularly important in applications with high demands on smooth operation, precision, and bearing life. Vibration severity B motors therefore offer lower mechanical stress, reduced noise emissions, and improved service life of bearings and shafts compared to motors with vibration severity A.