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Types Of Dc Motors, Principle and Losses of Dc Motor


Electrical Dc motors play an important part in virtually every section of the industry, also, to also utilized in A wide variety of national applications. There are various types of motor-based on functionality and their voltage, you may select the suitable one. Electric motors are classified into 3 major sections, that's DC engine, AC engine, and special purpose motors. And a few commonly used special-purpose motors are stepper engine, servomotor, linear induction engine, etc. In this article, we are discussing Dc motor and It’s losses
Different types of DC Motors - We all know that any engine has two elements within it, the armature and specifically the field. Mainly the electric motor that is operated by Direct current(DC) is called DC motors.
Direct Current motors are categorized according to the connection o the field winding with the armature. There are 3 types of DC Motor:
  1. Shunt-wound DC motor
  2. Series wound DC motor
  3. Compound wound DC motor
One by one we are covering all the topics

Principle of DC Motors

When a current-carrying conductor placed in a magnetic field then the conductor feels this force is called Torque. The direction of the rotating of the conductor always follows Fleming’s Left-hand rule. According to this rule, if the index finger, middle finger and thumb of your left hand are extended mutually perpendicular to each other and if the index finger represents the direction of magnetic field, middle finger indicates the direction of the current, then the thumb represents the direction in which force is experienced by the shaft of the DC motor.
Here is a DC motor, the supply voltage E and current I is given to the electrical port or the input port and we derive the mechanical output torque T and speed ω from the mechanical port or output port. Parameter K relates the input and output port variables of the electrical energy.
                           Torque(T)= K*I and E = Kw

Series Wound DC Motor

In Series Wound Dc Motor Field winding generates the static magnetic field, and the coil resembles a slice of conductor kept to the field. Due to the magnetic field, armature encounters a power and causes to create sufficient torque to rotate the engine shaft. Now, the classification of the DC motor may be done by field winding's connections and armature winding. The word series defines that, here armature coil and the field coil are connected in a show circuit. The same current will flow throughout the armature and field. Let's think about the field is Ise and the current is Ia. As the Kirchhoff law present will be I = Ia = Ise.

DC Shunt Motor

 The Dc Shunt Motor is a few turns of thick copper wire that is utilized to design the field coil. DC Shunt Motor - In the same manner, in DC shunt Motor the area coil and also armature winding is connected in parallel connection. The kind of DC motor is extremely common in practical use. Let's think about the armature present is Ia and the field present is Ish. As per the Kirchhoff present law, Total present  I = Ia = Ish, where Ish is a shunt area present.

Compound wound DC motor

To withstand this voltage, the area coils are designed with fine copper cables and consist of several turns of turns. DC Compound Motor - This kind of DC motor is essentially a hybrid module of DC show motor and DC shunt motor. Applying also the concepts of the earlier discussion, also the shunt coil was created with numerous turns of fine copper wires, to receive the full input voltage. Whereas, the show area coil is made with few turns of thick copper wires, to provide a minimal resistance path.

Permanent Magnet Dc Motor(PMDC)

 Permanent Magnet Dc Motor or PMDC motors use permanent magnets to develop also the area excitation. The field magnets are mounted in the casing, and the other components remain the same, such as DC armature, carbon brushes, and commutators. As the field flux isn't Changeable, so the speed of a PMDC engine may be just controlled by adjusting the armature voltage.

Losses In DC Motor

1. Copper Loss or Winding Loss:- The Copper Loss of the winding takes place when the current flow through the winding. The loss occurs due to the resistance of the winding. In Dc motor, there are two winding primary and secondary winding. The copper loss occurs in both the winding.  The loss in  Armature or winding is basically around ( 25 – 30)% of the total loss.
The General equation of copper Loss is I2R.

2.   Hysteresis Loss:- The Hysteresis Loss is the portion of the armature which is under S-pole, after completing half an electrical revolution, the same piece will be under the N-pole, and the magnetic lines are reversed to overturn the magnetism inside the core. The constant method of magnetic reversal within the coil, consume some quantity of the energy that is termed as hysteresis loss. The proportion of loss depends on the standard and volume of the iron.

3.      Eddy Current Loss: -Faraday's Law of Electro Magnetic Induction says that when an iron core rotates in the Magnetic field, an emf is also induced in the core. Similarly, when armature rotates in the magnetic field, the small amount of emf induced in the core which allows the flow of charge in the body due to the conductivity of the core. This current is useless for the machine. This loss of current is called eddy current. This loss is almost constant for the DC motor. It could be minimized by selecting the laminated core.

4.      Mechanical Loss:- It is a frictional loss that occurs due to mechanical friction between rotor and stator. This Loss is 10% of the total loss.

5.      Stray Loss:- The Stray loss is the mash-up of loss occurs in dc motor due to current and flux also the air gap between the rotor and stator. This loss is very minimal only 1%.

Principle of Operation of a DC Generator from eLearn.Punjab on Vimeo.

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