Phasor Diagram of Salient Pole Alternator

1. Electrical Machines-II
6th Semester, EE and EEE
By
Dr. Binod Kumar Sahu
Associate Professor, Electrical Engg.
Siksha ‘O’ Anusandhan, Deemed to be University,
Bhubaneswar, Odisha, India
Lecture-12

2. 2
Learning Outcomes: - (Previous Lecture_11)
 To analyse the armature reaction in salient pole alternator.
 To analyse the phasor diagram of salient pole alternator.
 To determine the voltage regulation of a salient pole alternator.

3. 3
Learning Outcomes: - (Today’s Lecture_12)
 To analyse the phasor diagram of salient pole alternator.
 To determine the voltage regulation of a salient pole alternator using
analytical method.

4. 4
Analytical method of determination of voltage regulation
(Analytical Method): -
At lagging power factor: -
E
V
IaR
a
jIdXd
jIqXq
E/
Id
Iq



Vcos

IaR
a
Vsin

jIaX
q
Vcos q aI R d dI X
O
A
B
C
D
jIdXq
 d d qI X X

F
G

5. 5
   
cos q a d dE V I R I X  
 From the right angle triangle, OBD,
sin
tan
cos
a q
a a
V I XBD BC CD
OB OA AB V I R




  
 
, sin , cosd a q aWhere I I and I I  

6. 6
At leading power factor: -
 Case I : When armature current Ia leads the terminal voltage (V) but lags the induced
emf (E).
E
V
jIdXd
jIqXq
E/
Id
Iq



Vcos
IaRa
VsinjIaXq
Vcos q aI R d dI X
Ia IaRa
A
O
B
C
D

7. 7
   
cos q a d dE V I R I X  
 From the right angle triangle, OBC,
sin
tan
cos
a q
a a
I X VBC DC DB
OB OA AB V I R




  
 
, sin , cosd a q aWhere I I and I I  

8. 8
At leading power factor: -
 Case I : When armature current Ia leads the terminal voltage (V) as well as the
induced emf (E).
E
V
jIdXd
jIqXq
E/
Id
Iq

 Vcos
Vsin
Vcos q aI R
Ia
IaRa
jIaX
q
IaRa
O
A
B
D
C

9. 9
   
cos q a d dE V I R I X  
 From the right angle triangle, OBC,
sin
tan
cos
a q
a a
V I XBC BD CD
OB OA AB V I R




  
 
, sin , cosd a q aWhere I I and I I  

10. 10
Thank you