1) The document discusses the key parts of a DC generator, including the yoke, pole core, field coils, armature core, armature winding, commutator, brushes and brush holders, and bearings. 2) It describes the function of each part, with the yoke providing a low reluctance path for magnetic flux, the field coils producing flux when excited, the armature winding placed in slots on the armature core, and the commutator facilitating current collection from the armature conductors. 3) The class covered the purpose of each generator component and conducted a quiz to test comprehension.

1. GOVT OF ANDHRAPRADESH
DEPT. OF EMPLOYMENT AND TRAINING
NAME : U.SATYANARAYANA MURTY
DESIGNATION : DEPUTY TRAINING OFFICER
TRADE : ELECTRICIAN
INSTITUTE : GOVT,I.T.I. (OLD), VISAKHA – 7.
SUBJECT : TRADE THEORY
WEEK NO. :
TOPIC : PARTS OF DC GENERATORS
DURATION : 50 Mints.
TEACHING AIDS : IMAGES,PPT

2. OBJECTIVES:
At the end of this lesson the trainee shall be able to:-
• D.C Generator parts and their functions

3. RECAP
In the previous, we have discussed
• Methods of dynamically induced EMF
• Fleming’s right hand rule
• Working of simple loop generator
• Principle of working of D.C. generator

4. Important parts of D.C. Generator
• Yoke
• Pole core and pole shoe
• Field coils
• Armature core
• Armature winding
• Commutator
• Brushes and brush holders
• Bearings

5. N
N
S
S
HOOK
FIELD
WINDING
POLE
ARMATURE
BASE
COMMUTATOR
YOKE

6. Parts of Generator
• Yoke is the outermost
cylindrical frame as shown
in Fig.
• It is made up of cast iron
• It provides the low
reluctance path to
magnetic flux

7. Yoke of Small machine

8. Pole core and Pole shoe
• Pole core is made-up of
cast iron as shown in Fig.
• Pole shoe is made-up of
cast iron laminations
• Pole shoe supports the
field coils and spreads
the magnetic flux in the
air- gap

9. Pole Shoe

10. Field Coils
• Field coils are made-up of
enamel coated copper or
aluminum wire as shown
in Fig.
• Placed on pole core
• Produces flux when
excited

11. Field coils
Field Coils

12. Armature core
• It is made up silicon steel
laminations
• Armature core is cylindrical
in shape as shown in Fig.
• Slots are provided on the
outer periphery

13. Armature core

14. Armature winding
• Armature winding is an
insulated copper wire.
• They are formerly wound
in the form of rectangular
coils
• They are placed in the
slots as shown Fig.
Armature winding

15. Armature winding
Armature winding
placed in slots Winding wire

16. Commutator
• It is cylindrical in shape
• It is made-up of high
conductivity hard
drawn copper
• It facilitates the
collection of current
from the armature
conductors as shown in
Fig.

17. Commutator

18. Brushes and Brush holders
• Brushes are made-up of
high grade carbon as
shown in Fig.
• Main function of the
brush is to collect current
from the Commutator
and supply it to the
external load

19. A = Armature
B = bar collector
C = brushes and brush holder
D = shaft.

20. Brushes
Brush Holder
Commutator

21. Brushes and Brush holders

22. Brushes and Brush holders

23. BEARINGS
What are these shown in the FIG ?

24. BEARINGS
• The function of the
bearings is to reduce
friction between the
rotating and the
stationery part of the
machine
• Types of bearings:
(a)Bush bearings
(b)Ball bearings
(c)Roller bearings

25. Fundamental parts of a direct current machine
1 = bearings 7 = collector
2 = lifting eyebolt 8 = stator
3 = bearings 9 = brushes and brush holder
4 = shaft support flange 10 = collector support flange
5 = ventilation turbine 11 = cover
6 = armature

26. Section plane of a direct current machine

27. Summary
In this class we have discussed
• Function of each part of a D.C. generator

28. Quiz
1. Armature core is made up of
(a) glass lamination
(b) silicon steel lamination
(c) wood laminations
(d) mica laminations

29. Quiz
1. Armature core is made up of
(a) glass lamination
(b) silicon steel lamination
(c) wood laminations
(d) mica laminations

30. Quiz
2. Which part of the generator converts a.c wave into
d.c wave?
(a) yoke
(b) field coil
(c) Commutator
(d) brush

31. Quiz
2. Which part of the generator converts a.c wave into
d.c wave?
(a) yoke
(b) field coil
(c) Commutator
(d) brush

32. Frequently Asked Questions
1. What are the important parts of a d.c
generator?
2. Write about armature core?
3. Explain Commutator with neat sketch?

33. THANK YOU
EE-303.6 33