Losses in DC Machine
Brushless DC Motors
Electrical Motor | Types Classification and History of Motor
Working of Electric Motor
DC Motor or Direct Current Motor
Working or Operating Principle of DC Motor
Torque Equation of DC Motor
Construction of DC Motor | Yoke Poles Armature Field Winding Commutator Brushes of DC Motor
Lap Winding Simplex and Duplex Lap Winding
Types of DC Motor Separately Excited Shunt Series Compound DC Motor
Series Wound DC Motor or DC Series Motor
Shunt Wound DC Motor | DC Shunt Motor
Compound Wound DC Motor or DC Compound Motor
Armature Reaction in DC Machine
Commutation in DC Machine or Commutation in DC Generator or Motor
Methods of Improving Commutation
Starting Methods to limit Starting Current and Torque of DC Motor
3 Point Starter | Working Principle and Construction of Three Point Starter
4 Point Starter | Working Principle and Construction of Four Point Starter
Speed Regulation of DC Motor
Speed Control of DC Motor
Ward Leonard Method of Speed Control
Testing of DC Machine
Swinburne Test of DC Machine
DC Servo Motors | Theory of DC Servo Motor
Permanent Magnet DC Motor or PMDC Motor | Working Principle Construction
Shunt Wound DC Motor | DC Shunt Motorvoltage, though there are separate branches for the flow of armature current and the field current as shown in the figure of dc shunt motor below.
Voltage and Current Equation of a Shunt Wound DC MotorLet us now consider the voltage and current being supplied from the electrical terminal to the motor be given by E and Itotal respectively. This supply current in case of the shunt wound dc motor is split up into 2 parts. Ia, flowing through the armature winding of resistance Ra and Ish flowing through the field winding of resistance Rsh. The voltage across both windings remains the same.
From there we can write Itotal = Ia + Ish
Construction of a Shunt Wound DC Motor
Self-Speed Regulation of a Shunt Wound DC MotorA very important and interesting fact about the dc shunt motor, is in its ability to self regulate its speed on application of load to the shaft of the rotor terminals. This essentially means that on switching the motor running condition from no load to loaded, surprisingly there is no considerable change in speed of running, as would be expected in the absence of any speed regulating modifications from outside. Let us see how?
Let us do a step-wise analysis to understand it better.
1) Initially considering the motor to be running under no load or lightly loaded condition at a speed of N rpm.
2) On adding a load to the shaft, the motor does slow down initially, but this is where the concept of self regulation comes into the picture.
3) At the very onset of load introduction to a shunt wound dc motor, the speed definitely reduces, and along with speed also reduces the back emf, Eb. Since Eb ∝ N, given by,
This can be graphically explained below.
5) As a result of this increased amount of net voltage, the armature current increases and consequently the torque increases.
Since, Ia ∝ Τ given by
The change in armature current and torque on supplying load is graphically shown below.
6) This increase in the amount of torque increases the speed and thus compensating for the speed loss on loading. Thus the final speed characteristic of a dc shunt motor, looks like.
From there we can well understand this special ability of the shunt wound dc motor to regulate its speed by itself on loading and thus its rightly called the constant flux or constant speed motor. Because of which it finds wide spread industrial application where ever constant speed operation is required.