Microtest 6363 - Page 15

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 Reactance (X) and Susceptance (B):
Reactance(X), in the analysis of AC circuits, reactance is represented with“X”; it is the imaginary part
of complex impedance used to represent the obstruction of inductance and capacitance to current. It
is similar to the obstruction of resistance to current in a DC circuit; in AC circuits (such as serial RLC
circuits), capacitance and inductance will also cause obstruction to current, and this effect is called
resistance. Its unit is ohm (Ω).
Susceptance(B) is defined as the reciprocal of reactance in power electronics; it is the imaginary part
of admittance and can be divided into inductive susceptance and capacitive susceptance. It is the
reciprocal of reactance (B=1/X) and its unit is Siemens, abbreviated as (S).
 Reactance(X)
Measurement Type:
Serial Mode→Xs
*Reactance is only applicable to serial equivalent circuit models.
Related Formula:

sin
1
Z
B
X 

sin|| ZX
s

 Susceptance(B)
Measurement Type:
Parallel Mode→Bp
*Susceptance is only applicable to parallel equivalent circuit models.
Related Formula:

sin
1
Y
X
B 
 sin||YB
p

 
22
s
X R Z 
 
22
p
X R
RX
Z


 
22
s
B G
GB
Y


 
22
p
B G Y 