Presentation on Excided Shunt DC Motor.pptx

shunt Motor

1. Shunt DC Motor Name Department Email

2. Conten t s: Construction Working Principle/Operation Equivalent Circuit Terminal Characteristics Speed Control Methods Application 2

3. Construction The stator of shunt dc motor contain core and winding. The core is made of silicon steel(97% Iron,3% silicon). The winding is made of copper with high class insulation(class C). 3 Stator with visible poles

4. Construction The rotor of shunt dc motor contain core , winding , commutator and corban brushes . The core is made of silicon steel(97% Iron,3% silicon). The winding is made of copper with high class insulation(class C). The C ommutator is also made of copper with insulated material mica between copper segments. 4

5. Working Principle/Operation of shunt dc motor When a current carrying conductors are placed in the magnetic field, then a force is act on the conductors. Due to this force, Electromagnetic torque is produced and motor rotate. 5

6. Shunt DC motor: Equivalent Circuit A shunt dc motor is a motor whose field circuit get its power directly across the armature terminals of the motor. 6

7. Shunt DC Motor : Terminal Characteristics Consider the DC shunt motor. From the Kirchoff’s Law Induced Voltage Substituting the expression for induced voltage between V T and E A . Since, then current I A can be expressed as 7

8. Finally, solving for the motor's speed yield Torque-speed characteristic of a shunt or separately excited dc motor This equation is a straight line with a negative slope. 8

9. Shunt DC Motor : Terminal Characteristic Torque-speed characteristic of a motor with armature reaction present . Affect of Armature Reaction (AR) will reduce flux as the load increase (  ind also increase), so it will increase motor speed (). If the motor has compensating winding, the flux () will be constant. 9

10. Shunt DC Motor : Speed Control 1 : Changing The Field Resistance (flux affected) Increasing R F causes I F Increasing τ ind makes to decrease. Deceasing I F decreases  . (graph flux vs current) Decreasing  lowers Decreasing E A increases I A Increasing I A increases with the change in I A dominant over the change in flux ( ) . and the speed ω increases . 10

11. Shunt DC Motor : Speed Control Increasing speed to increases E A = K  again. Increasing E A decreases I A . Decreasing I A decreases until at a higher speed ω Decreasing R F would reverse the whole process, and the speed of the motor would drop The effect of field resistance speed control on a shunt motor’s torque speed characteristic: over the motor’s normal operating range 11

12. Shunt DC Motor : Speed Control 2: Changing The Armature Voltage Armature voltage control of a shunt (or separately excited) dc motor. An increase in V A increases I A [= (V A  – E A )/R A ] Increasing ω increases E A (= K  ω  ) Increasing I A increases Increasing τ ind makes increasing ω. 12

13. Shunt DC Motor : Speed Control Increasing E A decreases I A [ = (V A – E A  )/R A ] Decreasing I A decreases τ ind until at a higher ω. The effect of armature voltage speed control on a shunt motor’s torque speed characteristic The speed control is shiftted by this method, but the slope of the curve remains constant 13

14. Shunt DC Motor : Speed Control 3 : Inserting Resistor in Series with Armature Circuit Add resistor in series with R A The effect of armature resistance speed control on a shunt motor’s torque – speed characteristic Equivalent circuit of DC shunt motor Additional resistor in series will drastically increase the slope of the motor’s characteristic, making it operate more slowly if loaded 14

15. Shunt DC Motor : Speed Control This method is very wasteful method of speed control, since the losses in the inserted resistor is very large. For this it is rarely used. The above equation shows if R A increase, speed will decrease 15

16. Applications of Shunt dc motor: Centrifugal pumps: Shunt DC motors are used to drive centrifugal pumps in a variety of applications, such as water and sewage pumping, irrigation, and industrial processes. Lifts: Shunt DC motors are used to power lifts, also known as elevators, in commercial and residential buildings. Weaving machines: Shunt DC motors are used to drive weaving machines in textile mills. Conveyors: Shunt DC motors are used to drive conveyor belts in a variety of industries, such as manufacturing, food processing, and logistics. Blowers and fans: Shunt DC motors are used to drive blowers and fans in a variety of applications, such as ventilation, heating and cooling, and industrial processes. Lathe machines: Shunt DC motors are used to power lathe machines, which are used to machine metal and other materials . 16

17. References Stephen J. Chapman, “Electrical Machinery Fundamentals”, McGraw Hill, 2003 . Austin Hughes, “Electric motors and drives”, 2005 P. C Sen , “ Principles of Electric Machines and Power Electronics ”,2013 33