Page 163 - Electrician - TT (Volume 1)

ELECTRICIAN - CITS

Inductive reactance

The opposition due to inductance of the coil in an AC circuit is called inductive reactance. It is denoted by XL . It
is measured in ΩIf L is the inductance of a coil, then its inductive reactance will be
XL = 2πfL
Where:

f supply frequency in Hertz
L inductance of the coil in Henry
XL Inductive reactance in Ohms.
From the formula.
XL = 2πfL,

Inductance L =XL/2 πf
Capacitive reactance
The opposition due to capacitance of a capacitor is called capacitive reactance. It is denoted by Xc. It is measured
in ΩIf C is the capacitance of a condenser , then its capacitive reactance will be

XC= 1/2πfc
Where;
f is the supply frequency
c is the capacitance of the circuit

XC = Capacitive reactance in Ohms
From the formula ,
Xc = 1 / 2πfC
Capacitance C = 1 / 2πfXc
Impedance
2
Z R X 2
The vector sum of resistance and reactance connected in an AC
circuit is called impedance R (X X c ) 2
2
L
OR
2 1 2
The total opposition offered by resistances and reactance in an AC R 2 fL
circuit is called impedance. It is denoted by the letter Z. 2 fC

The impedance , resistance and reactance can be denoted by the sides of a right angled triangle whose two sides
enclose an angle ө°
Z - hypotenuse

150
CITS : Power - Electrician & Wireman - Lesson 26-29