Any device that reduces human efforts & time in doing a particular work can be termed as a machine.

1. MACHINES??

2. What is a Machine??
Any device that reduces human
efforts & time in doing a particular
work can be termed as a machine.

3. Electrical Machines??
When we talk about electrical machines we are
restricting ourselves to:-
1) AC Machine, (Transformers, Induction machine,
Synchronous Machine etc.)
2)DC Machine, (DC Generators , DC Motors.)

4. DC MACHINE
Motor: The device which converts electrical energy
into mechanical energy is called a motor.

5. Generator: The device which converts mechanical
energy into electrical is called a generator.

6. Basic Principal of Generators
 Faradays law of electromagnetic induction states that
when a conductor or a coil is rotated in a magnetic field
an emf is induced, and if the
coil form a closed loop, currents
starts to flow in it.
Generator always works on
Fleming’s right hand rule.

7. Basic Principal of Motors
 If a conductor carrying current is placed in a magnetic
field force is act on the conductor.
Motors works on fleming’s
left hand rule.

8. Construction of Dc machine
•Stator is the static part of machine
•Rotor is the rotating part of machine

9. Constructional features
A dc machine works as a DC generator
when it is driven by a prime mover.
The same machine works as a DC motor
when electrical energy is supplied to it.

10. Main parts of DC Machine

11. Static parts of dc machine
Frame or yoke : yoke made of cast steel.
Outer framed machine – protection
Provide the flux path.
Pole :
 Pole is made of laminated steel sheet
 Pole houses the field winding.
Field winding :
 It is cupper wire winding
 It is responsible for set up of a field in which armature rotate.
Pole shoe :
 Face of the pole.
 Concave shape
 Distribute the main flux

12. INTERPOLE :To neutralize the effect of armature
reaction in the space in between two main poles, smaller
poles, called interpoles .

13. Rotating parts
The rotating part of the DC machine is also
known as armature.
Shaft :The Shaft houses the cylindrical armature.
Prime mover is case of generator & load in case of
motor is connect with the shaft.
Commutator& brushes:
1)Convert A.C. of armatures in to DC output in
generator .
2)In motor it convert DC supply into AC.

14. Commutator which rotates with the armature is
made from a number of wedge-shaped hard
drawn copper bars or segments insulated from
each other and from the shaft.
Current is collected from the armature winding
by means of two or more carbon brushes,
mounted on the Commutator.

15. Complete View of Machine

16. Armature core made of laminated steel to reduce the
eddy current losses in core.
Slots are stamped on the periphery of the armature.
The armature slots house the armature winding.
Armature conductors in the slots are secured in their
places by hard wooden wedges or fiber glass wedges.

17. THANKS!!!