Electric motors - universal drives for the right turn
The history of the electric motor is closely linked to
the industrial revolution. Little by little, the electric motors replaced the
steam engines with the central shafts that powered several different machines.
Before the use of the electric motors, drive belts connected the central shaft
to the individual machines. But that also meant that the positioning of the
machine tools was linked to the position of the central drive shaft.
That changed radically with the electric motor. The
machines could be set up variably. The connection with a cable to the power
supply was usually the least of the problem.
The electric motor and physics
Physically, an electric motor does nothing other than
convert electrical energy into mechanical energy. As a rule, the conversion
takes place in rotational movement, but in rare cases linear movements (linear
motors) are also possible. Conversely, electric motors can also be operated as
a generator, i.e. mechanical movement can be converted into electrical energy.
This effect is the interaction of a stator and the rotor
(also called armature) rotating in the magnetic field of the stator. In
addition, there is the interplay of the poles to ensure rotation.
The current flow through the rotor is ensured by sliding
contacts or brushes. But brushless motors have also been developed.
The performance of the electric motor is physically
limited by the temperature. In the short term, electric motors can deliver more
than their nominal power. With a three-phase motor, the limit is the breakdown
torque (up to 2.5 times the nominal torque). In the case of a direct current
motor, the limit is around 1.9 times the nominal torque. In the case of a
direct current motor, in addition to the temperature, the pole reverser plays a
decisive role in the permissible overload.
Technical details such as the connection options for the
various types of electric motors and the influence on the behavior of the motor
are not dealt with any further here. The various types of anchors are also not
discussed further.
One of the great advantages of the electric motor is the
torque curve. The full torque is available immediately after start-up. Anyone
who has ever driven an electric car knows the effect.
The electric motor, its types and its designs
Electric motors come in different types and designs. The
main distinctions are the alternating current electric motor (AC motor) and the
direct current motor (DC motor). In the past, the DC motor was considered the
better motor in drive technology. With the further development of frequency
converters, however, the three-phase motor is also very variable in terms of
control and is more frequently used in machine drive technology.
Electric motors are available in a wide variety of
designs. Two of the best-known variants are the flange motor and the foot
motor.
Many manufacturers also offer electric motors directly as
gear motors. That is why you will find gear motors as a separate category on
tramao in addition to electric motors.
There are hardly any limits to the size and thus also the
performance of electric motors. Small motors (micro motors) with 0.1 watt exist
as well as large motors with 10 MW and more.
Where can electric motors be used?
The question must rather be where electric motors cannot
be used. Micro motors are used, for example, in model making or in camera
systems. Everyone knows other uses from the areas of kitchen appliances,
gardening tools, general tools, office supplies and house technology.
The electric motor has also become indispensable in
industry. Conveyor systems, machine tools or vehicles especially for indoor use
and in extreme cases in rolling mills are now electrically powered.
Step-motors and servomotors cover the areas where maximum
precision is required. Most of the high-precision incremental encoders or
encoders are already integrated in these drives.
How can you get electric motors?
At tramao you will find electric motors and gear motors
in multiple designs. There are new parts as well as used machines or completely
overhauled electric motors with new brushes and windings.
There are offers from many well-known manufacturers such
as Siemens, ABB, Bosch, Rexroth and Simotics.
Here, too, tramao is the right marketplace for motors and
engines.