Working of DC Generator and its types.ppt

Working of dc motor and generator

1. Electrical machines I

4. Principle of Operation
•Does not create electricity
•Faradays law
•Dynamically induced e m f.
•Flemings right rule.
e= N dΦ/dt.

5. Working of DC Generator

6. POSITION A POSITION B POSITION C

7. POSITION C POSITION D POSITION E

8. Analysis of Output waveform

9. Elementary Generator Armatures
Figure 1 Single Loop Figure 2 Coil of two
turns in series
Figure 3 Coil of two
turns in parallel
During operation the emf induced
• In Coils with two turns in series
Double that of coils in parallel
 Double that of single turn coil
Amount of current generated
 Half that of coils in parallel

12. Classification of DC Generators
•Permanent magnet type.
•Industrial generators use electromagnets.
•Figure 1
 shows an overview of this classification method each type of
generator.

13. Separately Excited Generator
•Field winding is separately
excited.

14. Self Excited DC Generator
(i) Shunt Generator
•Field winding parallel to armature winding.
•I
sh = V/R
sh
•I
a = I
L + I
sh
•E
g = V
t + I
a R
a+ V
b
•V
t = E
g – I
a R
a - V
b
•P
d = E
g I
a
•P
L = V
tI
L

15. Series DC Generator
•Field winding in series with armature winding.
•I
a = I
se = I
L = I
•E
g = V
t + I (R
a + R
se )
•V
t = E
g – I (R
a + R
se )
•P
d = E
g I
•VI = E
gI – I
2
(R
a + R
se )
= I [E
g – I(R
a- R
se)
= V
t I

16. Short Shunt DC Generator
•I
se = I
L
•E
g = V
t + I
a R
a +I
seR
se
•V
t = E
g – I
a R
a – I
se R
se
•P
d = VI
L
•I
sh = (V
t+I
seR
se)/R
sh

17. Long Shunt DC Generator
•I
se = I
a = I
L+ I
sh
•I
sh = V/R
sh
•E
g = V
t+ I
aR
a+ I
a R
se
•V
t = E
g – I
aR
a- I
a R
se
•P
d = E
gI
a
•P
L= V
tI
L

18. EMF Equation of DC Generator
•Φ, Z, P, A, A= 2, A = P, N, E
g
•dΦ = PΦ Webers
•dt = 60/N Second

19. Applications