Question

Three coils each having resistance of 10 ohms and inductance of 0.02H are connected in star across 440V, 50Hz, 3phase supply. Calculate the line current and total power consumed

Answer 1

The given load is star connected load.

L = 0.02 H

Inductive reactance X = 2 × π × 50 × 0.02 ≈ 6.28Ω

R = 10 Ω

Impedance, Z_ph = 10 + j6.28 = 11.81∠32.13°

Phase voltage, \(V_{ph} = \frac{440}{\sqrt 3} = 254.03 V\)

Line current

\(I_{ph} = I_L = \frac {V_ph}{z_ph} = \frac {254.03}{11.81} = 21.51 A\)

Power in three-phase is given by

\(P = \sqrt 3 \times 440 \times \frac{440}{\sqrt 3 \times 11.8} \times \cos 32.12 = 13 .89 k W\)