1 / 40

II UNIT D.C MOTORS

II UNIT D.C MOTORS. UNIT-II D.C. MOTORS : Principle of operation of DC Motor, Types of Motors, Back EMF Equation, Characteristics of DC motor, Torque Equation, DC Motor Starter (Three Point starter), Efficiency Calculation, Swinburne's Test and speed control of armature and field.

juanhall
Download Presentation

II UNIT D.C MOTORS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. II UNIT D.C MOTORS

  2. UNIT-II D.C. MOTORS : Principle of operation of DC Motor, Types of Motors, Back EMF Equation, Characteristics of DC motor, Torque Equation, DC Motor Starter (Three Point starter), Efficiency Calculation, Swinburne's Test and speed control of armature and field.

  3. DC Machines DC Motor DC Generator

  4. DC motor

  5. Force in a Conductor

  6. Diagram of a Simple DC Motor

  7. and it is indicated by Eb

  8. Net voltage across armature circuit = If Ra is the armature resistance , then

  9. This back e.m.f is also called as counter e.m.f and indicated by Eb Significance of Back E.M.F The presence of back e.m.f makes the dc motor a self regulating machine i.e. it makes the motor to draw as much armature current as is sufficient to develop the torque required by the load .

  10. Terminal Voltage Equation VT = voltage at motor terminals E = Back EMF induced in armature (V) IA = armature current (A) RA = armature resistance RA + + VT Eb - -

  11. Power Equation

  12. is the electrical input to the motor represents the copper losses in the motor is the electrical equivalent of mechanical power developed in armature

  13. Electric Motor

  14. TYPES OF D.C MOTORS • Shunt wound motors : in which the field winding is connected in parallel with the armature. (ii) Series –wound Motor : in which the field winding is connected in series with the armature (iii) Compound Wound Motor : which has two field windings ,one connected in parallel with the armature and the other in series with it

  15. Torque of a dc motor • The turning or twisting moment of a force about an axis. • It is measured as the product of force and radius at which it acts. • T=F*r N-m • Work done by force= F*2*3.14*r N-m

  16. Power developed=F*2*3.14*r *N • P=T*W watts (since T=F*r) • P=(2*3.14)NT/60 watts • P=NT/9.55 watts

  17. Armature Torque • If Ta is the torque developed by armature and N is speed in rps • P=Ta*2*3.14*N watts • Electrical power: Eb*Ia • Eb*Ia =Ta*(2*3.14*N) • Ta=(Eb*Ia)/(2*3.14*N)

  18. Eb=ZNP/A • Ta= (ZP/A)*(Ia/(2*3.14)) • Ta=0.159* ZIa(P/A) N-m • Ta is proportional to (Ia)

  19. SPEED CONTROL OF DC MOTORS 1. Vary the voltage supplied to the armature circuit while holding the field constant. 2. Vary the field current while holding the armature supply voltage constant. 3. Insert resistance in series with the armature circuit.

More Related