Short Notes: Magnetically Coupled Circuits | Short Notes for Electrical Engineering - Electrical Engineering (EE) PDF Download

 Page 2


 
 
 
 
 
 
Dot convention 
If a current enters the dotted terminals of one coil, then induced voltage in second coil has a 
positive voltage reference at dotted terminal of second coil. 
If a current enters undotted terminals of one coil, then induced voltage n second coil as a positive 
voltage reference at undotted terminals of second coil. 
 
 
 
                                                                                  
 
 
 
 
Series connection of coupled coils 
eq 1 2
L L L 2M ? ? ?
 
 
eq 1 2
L L L 2M ? ? ?
 
 
Parallel connection of coupled coils 
 
 
 
 
2
12
eq
12
L L M
L
L L 2M
?
?
??
                                                                
2
12
eq
12
L L M
L
L L 2M
?
?
??
 
?
12
Coefficient of coup
M
 k lg
L
n
L
i 
Page 3


 
 
 
 
 
 
Dot convention 
If a current enters the dotted terminals of one coil, then induced voltage in second coil has a 
positive voltage reference at dotted terminal of second coil. 
If a current enters undotted terminals of one coil, then induced voltage n second coil as a positive 
voltage reference at undotted terminals of second coil. 
 
 
 
                                                                                  
 
 
 
 
Series connection of coupled coils 
eq 1 2
L L L 2M ? ? ?
 
 
eq 1 2
L L L 2M ? ? ?
 
 
Parallel connection of coupled coils 
 
 
 
 
2
12
eq
12
L L M
L
L L 2M
?
?
??
                                                                
2
12
eq
12
L L M
L
L L 2M
?
?
??
 
?
12
Coefficient of coup
M
 k lg
L
n
L
i 
 
 
 
 
 
Equivalent circuits of linear transformers 
T-equivalent circuit 
 
 
 
 
 
 
 
a1
L L M ??
   
b2
L L M ??
 
C
LM ?
 
 
p- equivalent circuit 
 
2
12
A
2
L L M
L
LM
?
?
?
 
2
12
B
1
L L M
L
LM
?
?
?
 
2
12
C
L L M
L
M
?
?