The series motor is a type of direct current electric motor in which the armature and the inductor (or excitation winding) are connected in series. For this reason, the excitation current passing through the inductor is the same as the current passing through the armature, being absorbed by the motor.
This type of DC motor is also known as a series excitation motor. The structure of the series electric motor is characterized by having all the elements of the circuit in series: the armature and inductor windings. The series motor is distinguished by having a high torque when starting and a very variable speed depending on the load, which makes it an unstable motor.
Series engine features
The main features of the standard electric motor are:
- High starting torque : When started, the series motor produces a very high torque, making it ideal for applications requiring high starting force.
- Variable Speed - The speed of the series motor varies considerably with load. Under no load, speed can increase dangerously, making this motor unsuitable for applications that frequently operate at idle.
- Risk of overload : Operating the motor at no load can be dangerous because the speed can increase excessively, because when the load decreases, the flux in the inductor decreases and therefore the speed increases.
- Constant power : The power delivered by the engine tends to be almost constant at different speeds.
- Stability against voltage variations : Sudden variations in the supply voltage have little effect on the motor, since an increase in voltage causes an increase in intensity, which increases both the flux and the electromotive force, thus stabilizing the absorbed intensity.
Uses and applications of the series motor
Due to its characteristics, the series motor is used in applications requiring high torque. Some examples include:
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Electric traction : Trams, locomotives and other electric traction vehicles use series motors because of their ability to generate high torque from start-up.
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Industrial Applications : Used in cranes, elevators and other industrial equipment that requires a strong and robust start.
Examples of inappropriate applications
The use of this type of motor would be inappropriate for portable power tools. A drill could not use a series motor because, when drilling is complete, the machine would operate in a vacuum, which would cause the speed of the drill to increase dangerously, putting the user at risk.
Summary
The series motor is a DC motor characterized by its high starting torque and variable speed depending on the load. It is ideal for applications requiring high initial force, such as electric traction and heavy industrial equipment.
However, its use is not suitable for portable tools or applications that frequently operate without load due to the risk of overspeed and lack of stability.
