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Useful information about three-phase and alternating current motors
Whether efficiency, service life or speed - AC and three-phase motors differ in different aspects from DC motors. These two types of engines are not directly coincident. In our guide you will learn how the two motors differ and what criteria you have to pay attention to when buying them.
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What was a three-phase and was an AC motor?
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What are the differences between the two variants?
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What was to be taken into account when purchasing the machines?
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Bottom line
What was a three-phase motor and what was an AC motor?
In principle, both types of motors have the same function: They convert electrical energy into mechanical motion. This clearly shows the commonality with other electromechanical drive technologies and the differentiation from internal combustion engines. But here the similarities to other electric motors and also between three-phase and alternating current motors are already heard.
What are the differences between the two variants?
The differentiation by name already illustrates the different power supply. This has an impact on the design, performance and application area of the two motor versions:
Three-Phase AC Motors
The name of the three-phase motors is due to the supply of a three-phase alternating current. The motor must be supplied with this power via three separate conductors, so the conversion of the electrical power into mechanical power is a bit more complex. In the motor itself there are three electromagnet coils in a circle or star shape, which are located at an angle of 120° to each other. If these are periodically supplied with an alternating voltage offset to the other coils of 120°, the individual solenoid coils are activated differently.
The conversion follows in principle that of a normal electric motor: The change of direction of the rotating magnetic field through the coils supplied at different times in the external stator acts on a moving rotor in the center - for example consisting of another magnet. From this, the mechanical movement is transferred to connected elements such as a shaft.
Three-phase motors can be divided into two sub-categories: Synchronous and asynchronous three-phase motors. The biggest difference here is that for synchronous motors the frequency of the rotor and the magnetic field is the same, for asynchronous motors the frequency is offset. Induction motors are more robust and inexpensive to manufacture and are therefore more widely used than their synchronous counterparts.
AC Motors
AC motors are also operated with three-phase alternating current, but only use one phase of the current. Therefore, they are also referred to as single-phase AC motors, whereby the term AC refers to the alternating voltage of the phase used.
In contrast to the three-phase motors, the magnetic field direction is not specified for the alternating current motor due to the use of only one phase. Therefore, these motors need additional components that determine the direction of the magnetic field and help the motor to start up.
Since the AC motors only use one phase, they are mainly used for applications with low power ratings. These motors can also be divided into synchronous and asynchronous versions.
What was to be taken into account when purchasing the machines?
As with any type of electrical drive, the basic technical data, such as nominal voltage and current, operating temperature and required efficiency are important factors for three-phase and alternating current motors, which must be taken into account when making the purchase decision. In addition, you should pay particular attention to the following purchase criteria:
Type decision: Right at the start of the discussion, the question should be about the type of motor used, whereby the three-phase versions are primarily suitable for performance-demanding tasks, while the AC drives are suitable for applications with smaller outputs.
Rated speed: The individual versions of the motors have different speeds. This metric indicates how high the maximum engine power is in revolutions per minute. It is essential to take into account the rated speed, as it is the basis for the possibilities for the desired use of the motor.
Design/type: The design usually also influences the type decision, since AC motors are usually smaller and can therefore be used in a variety of areas. In addition to the size, however, other aspects must be taken into account here: The design categories provide information on the mounting and orientation of the motor: B3 or B14 stand for horizontally aligned motors, for example. The former have feet for mounting, while the latter have a flange. The IP standards also indicate suitability for tougher environmental conditions. Depending on the intended use, their role is extremely important and must therefore be taken into account.
Bottom line
AC and three-phase motors are different types of motors, but they complement each other perfectly due to their differences in handling the respective requirements. Our advice will help you find the right product for your solution. Further information on the individual motors can also be found on the detailed product pages.