Question

A balance delta-connected load is supplied by a 60=Hz three-phase source with a line voltage of 240 V. Each load phase draws 6 kW at a lagging power factor of 0.8. Find the load impedance per phase and the line current.

Answer 1

Given information:

Frequency, f = 60 Hz Line voltage, V = 240 V Phase power, P = 6 kW Power factor, cos(θ) = 0.8

We know that apparent power S = P/cos(θ) Now, apparent power S = 6/0.8 = 7.5 kVA

We also know that the power in a three-phase system is given by: P = sqrt(3) V I cos(θ) where I is the line current.

Therefore, I = P / (sqrt(3) V cos(θ)) I = 6 x 1000 / (sqrt(3) x 240 x 0.8) I = 14.97 A (approx)

The load impedance Z is given by: Z = V / I Z = 240 / 14.97 Z = 16.03 Ω (approx)

Therefore, the load impedance per phase is 16.03 Ω and the line current is 14.97 A (approx).