Everything you need to know about speeds, pole numbers, and the right motor selection.
What determines the speed of an electric motor?
Die Speed of an electric motor is primarily determined by the mains frequency (e.g. 50 Hz in Europe) and the number of motor poles . In asynchronous motors, the most common type in industry, the so-called slip also influences the actual speed, which is always slightly lower than the theoretical synchronous speed.
How can I change the speed of my electric motor?
Die Speed of electric motors can be adjusted in various ways: Frequency converters enable continuous regulation, pole-switchable motors offer fixed speed levels (e.g. through Dahlander connection), and pre-geared transmissions mechanically change the output speed while simultaneously adjusting the torque. ATEK Drive Solutions offers servomotors, gear boxes, and comprehensive consulting for this purpose.
What is the difference between synchronous speed and rated speed?
Die Synchronous speed is the theoretical speed of the rotating magnetic field in the motor, calculated from mains frequency and pole pair count (e.g. 1500 rpm at 4 poles and 50 Hz). The rated speed is the actual operating speed of the motor under rated load, which is indicated on the nameplate and is always slightly lower in asynchronous motors due to the slip. (e.g. 1450 rpm).
When are pole-switchable motors a good choice for speed control?
Pole-switchable motors are ideal for applications that require two or three defined, fixed speed levels, such as in fans, pumps, or certain machine tools. They often represent a cost-effective and robust solution when continuous regulation is not necessary.
How do gear boxes affect the speed and torque of an electric motor?
A gear box is used to reduce the usually high Speed of an electric motor to a lower output speed that is suitable for the application simultaneously.At the same time, the torque supplied by the motor is increased inversely proportional to the change in speed (minus gear box losses). ATEK Drive Solutions uses a modular system to optimally match gear boxes to the required speeds and torques. (abzüglich Getriebeverlusten). ATEK Drive Solutions nutzt ein modulares Baukastensystem, um Getriebe optimal auf die benötigten Drehzahlen und Drehmomente abzustimmen.
What typical rated speeds do standard industrial motors have at 50 Hz?
Standard asynchronous motors for industrial operation at 50 Hz have typical rated speeds that are slightly below the synchronous speeds: approx. 2750-2950 rpm (2-pole), approx. 1400-1480 rpm (4-pole), approx. 900-980 rpm (6-pole) and approx. 680-740 rpm (8-pole)..
What advantages do frequency converters offer for the speed control of electric motors?
Frequency converters allow for a continuous and precise adjustment of the electric motor speed by changing the supply frequency and voltage. This leads to significant energy savings (especially at partial load), smooth starting and stopping, process optimization, and the ability to easily implement different production speeds. How do I choose the right motor speed for my specific application?
Selecting the correct motor speed requires a detailed analysis of the
Die Auswahl der korrekten Motordrehzahl erfordert eine genaue Analyse des required torque at the target speed, the load profile, the desired dynamics, and the environmental conditions. It is important to consider the entire drive train. ATEK Drive Solutions supports you with technical advice in the design and selection of the optimal drive solution, including gear boxes and motors.
Die Speed of an electric motor is fundamentally dependent on the mains frequency and the pole count;in asynchronous motors, the system-related slip reduces the synchronous speed to the actual rated speed. This understanding is the basis for any drive design.
For flexible adjustment of the electric motor speed suitable frequency converters for continuous control, pole-switchable motors for fixed steps, and gear boxes for converting speed and torque. The use of frequency converters can reduce the, polumschaltbare Motoren für feste Stufen und Getriebe zur Wandlung von Drehzahl und Drehmoment. Der Einsatz von Frequenzumrichtern kann den energy consumption in variable load profiles by up to 30%..
A precise selection of the motor speed and technology tailored to the application, considering torque, design, and energy efficiency (e.g. IE4 classes), is crucial for und -technologie unter Berücksichtigung von Drehmoment, Bauform und Energieeffizienz (z.B. IE4-Klassen) ist entscheidend für maximum plant productivity and cost-effectiveness and can significantly increase the system lifespan by more than 20%..Discover the secrets of electric motor speed! This article explains the key factors, from pole counts to efficient control, and helps you find the optimal solution for your application.
The speed of an electric motor is critical for the performance of your application. But how is it related to pole count, frequency, and design? We explain it to you. Do you need personalized advice? Contact us now with our experts!
Do you need assistance in selecting the right electric motor for your application?
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Understanding: Mastering the basics of electric motor speed is a crucial aspect of drive technology. This article discusses decisive factors for optimizing your drive solution and ensuring performance for your application, especially regarding the
Die Auswahl der korrekten electric motor speed ist ein wichtiger Aspekt der Antriebstechnik. Dieser Artikel behandelt entscheidende Faktoren zur Optimierung Ihrer Antriebslösung und Sicherstellung der Leistung für Ihre Anwendung, insbesondere im Hinblick auf die speeds of electric motors..
What is speed?
Speed (rpm), often referred to as rotational speed, is the number of revolutions of a shaft per minute. It is critical for the design of drive trains and the working speed of a machine. ATEK Drive Solutions GmbH enables various configurations to achieve the required speed through a modular system and thus the appropriate speeds for electric motors..
Why is speed important?
Requirements vary (slow conveyors to high-speed centrifuges). Motor speed affects process speed, volume flow, and precision. A wrongly selected speed of an electric motor can lead to inefficiency, wear, or failures. In motor selection (e.g. high-performance servomotor) the target speed is an important parameter. The power of the electric motor is often closely linked to the achievable speeds of the electric motor. Analyze: Deciphering the physics of frequency, pole count, and slip – fundamentals for
Analysieren: Physik von Frequenz, Polzahl und Schlupf entschlüsseln – Grundlagen für speeds of electric motors.
Synchronous speed vs. actual speed in electric motors.
Synchronous speed (a theoretical value calculated from mains frequency and pole pair count) deviates from the actual, lower speed of the electric motor due to slip in asynchronous motors. A 4-pole motor (50 Hz) with 1500 rpm synchronous speed actually runs, for example, at 1450 rpm.
- Synchronous speed is a theoretical value calculated from mains frequency and pole pair count, and a fundamental aspect of speeds of electric motors..
- in asynchronous motors, the actual speed is always lower than the synchronous speed due to slip.
- The formula for calculating synchronous speed is: n_s = (f * 60) / p, where f is the mains frequency and p is the pole pair count.
- A typical example is a 4-pole motor (2 pole pairs) at 50 Hz, which has a synchronous speed of 1500 rpm; this is a common rated speed for such electric motors..
- Slip describes the difference between synchronous speed and the actual mechanical speed of the rotor.
- Slip is essential for torque generation in asynchronous motors.
- Considering slip is an important aspect when buying electric motors, to achieve the desired operating speed and thus the correct speeds of the electric motor. for the application.
Formula for calculating synchronous speed
The formula for calculating synchronous speed is: n_s = (f * 60) / p (where f is the mains frequency and p is the pole pair count). Example for Speed of an electric motor: 2 pole pairs (corresponding to 4 poles), 50 Hz mains frequency: (50 * 60) / 2 = 1500 rpm synchronous speed. More on the topic of slip in asynchronous motors..
Example calculation: 50 Hz, 4-pole motor
A 4-pole asynchronous motor (corresponding to 2 pole pairs) on the 50 Hz grid has a synchronous speed of 1500 rpm. In practice, the actual speed of this electric motor is below that due to slip (e.g. at 1440 rpm).
The influence of slip in asynchronous motors
Slip, the difference between the synchronous speed of the magnetic field and the mechanical rotor speed, is necessary for inducing torque in asynchronous motors. A motor with an actual speed of 1420 rpm, operating at 50 Hz with 4 poles, has a slip of about 5.3%. This is an important factor in selection and buying electric motors, to achieve the desired speeds of the electric motor. .Control: Methods and technologies for regulating the speeds of electric motors. to be used optimally.
Pole-switchable motors to control the speeds of electric motors.
Pole-switchable motors offer defined speed levels by changing the pole count (e.g. using Dahlander connection). These are ideal for applications such as fans or pumps, where different, fixed speeds of the electric motor. are needed. JS-Technik offers such motors in their range.
Functionality and applications
By switching parts of the windings, the pole count and thus the speed of the electric motor due to slip in asynchronous motors.changes. For example, switching from 4 to 8 poles halves the speed from approx. 1500 rpm to 750 rpm at a mains frequency of 50 Hz. Such motors are used, for example, in crane systems.
Star-delta start
The star-delta start limits the high starting current of larger asynchronous motors by switching from star to delta connection during the start-up. This does not directly affect the final speed but protects the motor and the grid.
Frequency converters for variable electric motor speeds.
Ein Motor with frequency converter allows for continuous control of the speeds of the electric motor. by adjusting frequency and voltage. This saves energy and optimizes processes. ATEK also offers regulated gear motors with integrated frequency converter that enable precise electric motor speeds. control.
Prinzip und Vorteile
Frequenzumrichter erzeugen eine variable Ausgangsfrequenz und -spannung für den Motor. Die Vorteile sind vielfältig: Energieeffizienz, sanfter Anlauf und Stopp sowie die exakte Anpassung der speed of the electric motor due to slip in asynchronous motors. an den Prozess. ATEK nutzt diese Technologie beispielsweise für Servomotoren.
Gear motors for adapting the speeds of electric motors.
Gear motors are used to reduce the high speeds of electric motors. while simultaneously increasing the torque. The correct selection of the gear is crucial for the application. ATEK supplies bevel gear planetary gearboxes for this purpose, for example, and utilizes a modular system for a wide range of configurations.
Adjustment of torque and speed
A gearbox translates the motor speed and torque. A translation of 10:1, for example, converts a motor speed of 1500 RPM into an output speed of 150 RPM, while the torque increases by a factor of 10. This is a common means to speeds of electric motors. adapt to requirements.Identify: Influencing factors and limits of the maximum speeds of electric motors. recognize
Rotor inertia and mechanical limits for electric motor speeds.
Mechanical limits of the rotor, caused by its inertia and the centrifugal forces that occur at high rotational speeds, limit the maximum achievable speed of the electric motor due to slip in asynchronous motors.. Special applications that require extremely high speeds of electric motors. up to 250,000 RPM and more necessitate special constructions.
- The rotor inertia and the mechanical loads caused by centrifugal forces set natural limits for the achievable maximum speed of an electric motor.
- The winding design and current limitation are essential electrical design factors that influence the speed characteristics and heat generation of the motor, directly affecting the possible speeds of the electric motor. performance.
- Saturation effects in the core material of the motor can limit the magnetic flux and thus the torque and speed, particularly in high-performance motors and their rotational speeds is relevant.
- The intended operating duration (e.g., S1 for continuous operation) and the associated maintenance effort differ significantly between brushed motors (higher wear) and brushless motors (lower maintenance), which can influence the choice of the optimal electric motor speed performance.
- Brushless motors offer advantages in terms of longevity and reduced maintenance needs due to their design, especially at high speeds of electric motors.. Brushed motors are often cheaper to purchase.
- Choosing the right motor type, for example, a suitable three-phase motor, considering operating duration, maintenance aspects, and the required speeds of the electric motor., is crucial for reliability.
Current limitation and winding design
The electrical design, such as winding design and current limitation, significantly affects the achievable speed of the electric motor due to slip in asynchronous motors. and its heat generation.
Core materials and saturation effects
The saturation of the core material limits the magnetic flux and thus the torque and the maximum possible speed of the electric motor due to slip in asynchronous motors.. This is particularly relevant for high-performance motors like ATEK’s servo motors, designed for specific rotational speeds applications.
Operating duration and maintenance in the context of electric motor speed
Brushed motors are less suitable for continuous operation (S1) at high rotational speeds than brushless motors. ATEK is happy to advise you in selecting the appropriate three-phase motor and optimal speeds for your electric motor..
Brushed vs. Brushless Motors
Brushless motors require less maintenance and have a longer lifespan, especially in demanding rotational speeds. Brushed motors, on the other hand, often have a lower initial cost but are more maintenance-intensive.Select: Find the suitable electric motor with optimal rotational speeds torque and speed requirements for
The precise tuning of torque (e.g., 200 Nm at 50 RPM for conveyors) and the electric motors.
(e.g., 10,000 RPM at 5 Nm for centrifuges) is crucial for the efficiency and longevity of the application. The correct choice of the speed of the electric motor due to slip in asynchronous motors. (z.B. 10.000 U/min bei 5 Nm für Zentrifugen) ist entscheidend für die Effizienz und Langlebigkeit der Anwendung. Die korrekte Wahl der speeds of electric motors. application is central.
High-torque applications
Applications such as extruders or mixers require high torque, which is often achieved by slow-running motors or by employing gear motors to reduce the electric motor speed speed. ATEK also develops special gearboxes for this purpose.
Motor designs and standards (IEC 34-7)
The IEC 34-7 standardizes the design of electric motors (e.g., B3, B5, B14), facilitating exchange and integration. ATEK supplies electric motors in all common designs, suitable for the required rotational speeds.
B3, B5, B14 designs.
The designs B3 (foot-mounted), B5 (flange-mounted), and B14 (smaller flange) are widely used. ecoDrives offers a wide range of standard motors in these designs, suitable for various speeds of electric motors. applications.
energy efficiency classes (IE1 to IE4) and their relation to electric motor speeds.
The IE classes (IE1 to IE4) define the efficiency of electric motors. Since 2023, the energy efficiency class IE4 is mandatory for motors in the power range of 75 to 200 kW. An electric motor with brake can also meet high efficiency standards, regardless of its specific speed..Benefit: Current trends and future developments in speeds of electric motors. drive technology
Integrated motor control for optimized electric motor speeds.
Integrated controls, such as frequency converters mounted directly on the motor, reduce the cabling effort and the required space. This enables more precise and flexible control of the speeds of electric motors.. ATEK is closely monitoring this trend, especially for servo motors with integrated controllers.
- Integrated motor controls, like frequency converters directly on the motor, reduce wiring and space and optimize control of the speeds of electric motors..
- A significant trend in drive technology is the demand for custom solutions and customer-specific applications to optimally meet highly specific application requirements, including precise electric motor speeds.specifications.
- ATEK Drive Solutions GmbH utilizes its modular system to customize individual drive components such as shafts and flanges or complete systems tailored to specific speeds of electric motors. requirements.
- Pole-switchable motors, which are often exempt from strict IE efficiency regulations and thus may also be available in IE1 version, represent a cost-effective solution for applications with stepped speed requirements in electric motors. overview.
- The Dahlander circuit is a common technique for pole-switchable motors, allowing typically two fixed speeds of the electric motor. in a 2:1 ratio (e.g., by switching from 4 to 8 poles).
- The deep understanding of all influencing factors on the speeds of electric motors. and expert advice, such as offered by ATEK Drive Solutions GmbH, is essential for achieving optimal and efficient plant performances.
Custom solutions and tailored options for electric motor speeds.
Tailored drive solutions that are precisely adapted to the required speeds of electric motors. and other parameters are increasingly in demand. ATEK Drive Solutions GmbH develops custom shafts, flanges, or complete systems, supported by a flexible modular system to ensure optimal electric motor speeds. performance.
Pole-switchable motors in detail – an option for variable rotational speeds
Pole-switchable motors (e.g., from JS-Technik, with 2-3 fixed rotational speeds) are often exempt from strict IE regulations, allowing IE1 versions as well. Typical power ranges start from 0.22/0.15 kW upwards and offer a cost-effective means to realize different speeds for electric motors. solutions.
Dahlander circuit
The Dahlander circuit (with 6 terminals on the terminal board) is a common method to achieve two different rotational speeds in a 2:1 ratio (e.g., by switching from 4 to 8 poles, leading to speeds of the electric motor. about 1500 RPM and 750 RPM respectively).
The understanding and correct selection of the electric motor speed are crucial for the success of your projects. Consider all factors to achieve optimal plant performance. For comprehensive advice on the speeds of electric motors. and their selection, ATEK Drive Solutions GmbH is happy to assist you.
