Short Notes: Synchronous Machines | Electrical Machines - Electrical Engineering (EE) PDF Download

 Page 2


 
 
 
 
 
o Pitch Factor, 
P
K = cos
2
?
 
o Induced emf 
? ?
ph P
 4.44 N f K ?? 
o For 
th
n harmonic 
 Induced emf 
? ?
ph P
 4.44 N f K ?? 
  
P
n
K = cos
2
?? ?
??
??
 
 To eliminate 
th
n harmonic 
              
n
 = 
22
??
 
    
? ?
180
 = electrical
n
? 
  Distributed  Winding 
   
number of slots
m = 
number of poles no. of phase ?
 
        
number of slots
Coil Span = 
number of poles
 
            ? ?
180
 =  electrical
coil span
? ; 
   Distribution Factor,  
? ?
d
m
sin
2
K 
m sin
2
?
??
??
??
?
?
 
   For 
th
n harmonic, ? is replaced by n ? 
      
d
mn
sin
2
K
n
m sin
2
?
??
??
??
?
?
??
??
??
 
 
Page 3


 
 
 
 
 
o Pitch Factor, 
P
K = cos
2
?
 
o Induced emf 
? ?
ph P
 4.44 N f K ?? 
o For 
th
n harmonic 
 Induced emf 
? ?
ph P
 4.44 N f K ?? 
  
P
n
K = cos
2
?? ?
??
??
 
 To eliminate 
th
n harmonic 
              
n
 = 
22
??
 
    
? ?
180
 = electrical
n
? 
  Distributed  Winding 
   
number of slots
m = 
number of poles no. of phase ?
 
        
number of slots
Coil Span = 
number of poles
 
            ? ?
180
 =  electrical
coil span
? ; 
   Distribution Factor,  
? ?
d
m
sin
2
K 
m sin
2
?
??
??
??
?
?
 
   For 
th
n harmonic, ? is replaced by n ? 
      
d
mn
sin
2
K
n
m sin
2
?
??
??
??
?
?
??
??
??
 
 
Page 4


 
 
 
 
 
o Pitch Factor, 
P
K = cos
2
?
 
o Induced emf 
? ?
ph P
 4.44 N f K ?? 
o For 
th
n harmonic 
 Induced emf 
? ?
ph P
 4.44 N f K ?? 
  
P
n
K = cos
2
?? ?
??
??
 
 To eliminate 
th
n harmonic 
              
n
 = 
22
??
 
    
? ?
180
 = electrical
n
? 
  Distributed  Winding 
   
number of slots
m = 
number of poles no. of phase ?
 
        
number of slots
Coil Span = 
number of poles
 
            ? ?
180
 =  electrical
coil span
? ; 
   Distribution Factor,  
? ?
d
m
sin
2
K 
m sin
2
?
??
??
??
?
?
 
   For 
th
n harmonic, ? is replaced by n ? 
      
d
mn
sin
2
K
n
m sin
2
?
??
??
??
?
?
??
??
??
 
 
Page 5


 
 
 
 
 
o Pitch Factor, 
P
K = cos
2
?
 
o Induced emf 
? ?
ph P
 4.44 N f K ?? 
o For 
th
n harmonic 
 Induced emf 
? ?
ph P
 4.44 N f K ?? 
  
P
n
K = cos
2
?? ?
??
??
 
 To eliminate 
th
n harmonic 
              
n
 = 
22
??
 
    
? ?
180
 = electrical
n
? 
  Distributed  Winding 
   
number of slots
m = 
number of poles no. of phase ?
 
        
number of slots
Coil Span = 
number of poles
 
            ? ?
180
 =  electrical
coil span
? ; 
   Distribution Factor,  
? ?
d
m
sin
2
K 
m sin
2
?
??
??
??
?
?
 
   For 
th
n harmonic, ? is replaced by n ? 
      
d
mn
sin
2
K
n
m sin
2
?
??
??
??
?
?
??
??
??
 
 
 
 
 
 
   
Leakage Flux 
Leakage flux links only one winding but not both so if it is present in stator, it won’t link to rotor & 
vise versa. 
Equivalent Circuit 
                                                                               
 
 
 
                     
s
X = synchronous reactance 
         
ar l
 X X ?? 
         =  sum of armature reaction & leakage reactance 
? ? ? ? ? ? ?
a a s
E V 0 + I (R jX ) , for Synchronous Generator 
? ? ? ? ? ? ? ?
a a s
E V 0 - I (R jX ) , for Synchronous Motor 
Where F is power factor angle (leading) 
for lagging power factor we replace F by “– F” 
Voltage Regulation 
  Voltage regulation 
EV
 100%
V
?
?? 
For zero voltage regulation 
   = 180 ? ? ?    
-1 s
a
X
 = tan
R
??
??
??
??
? 
             ? ? cos = load pf leading ?