Question

An electric lamp rated 10A/ 100V d.c. is to beoperated in a domestic line of 220V at 50 Hz a.c. Calculate the inductance of the choke coil required

Answer 1

Explanation:

Given An electric lamp rated 10 A/ 100 V d.c. is to be operated in a domestic line of 220 V at 50 Hz a.c. Calculate the inductance of the choke coil required

• We know that V l = √V^2 – V r^2
•                             = √(220)^2 – (100)^2
•                            = √38,400
•                             = 195.95 V
• Now V l = I X l
•              = I (2 π f L)
• Therefore L = V l / 2 π f I
•                    = 195.95 / 2 π x 50 x 10
•                      = 195.95 / 3,140
•                 L = 0.062 h

OR

• In DC, v = 100 v and I = 10 A
• So R = V / I
•          = 100 / 10
•          = 10 ohms
• Now V rms = 220 V and frequency = 50 hz, I rms = 10 A
• Z = V rms / I rms
•    = 220 / 10
•    = 22 ohms
• Now Z = √R^2 + X L^2
•    Or Z^2 = R^2 + X L^2
•        22^2 = 10^2 + X L^2
•       484 = 100 + X L^2
• Or X L^2 = 384
• Or X L = 19.6 ohms
• Now L = X L / 2 π f
•           = 19.6 / 2 x 3.14 x 50
•      Or L = 0.0624 h