Question

Refer to the circuit of Fig. and determine the resistance and reactance of the lagging coil load and the power factor of the combination when the currents are as indicated.

Answer 1

As seen from the Δ ABC of Fig..

 

5.6² = 2² + 4.5² + 2 × 2 × 4.5 × cos θ, 

∴ cosθ = 0.395, sinθ = 0.919. 

Z = 300/4.5 = 66.67 Ω 

R = Z cos θ = 66.67 × 0.919 = 61.3 Ω 

p.f. = cos φ = AC/AD = (2 + 4.5 × 0.395)/5.6 = 0.67 (lag)