Question

A balanced delta connected load is fed from a 3-$\varphi$ supply. For which, the phase c is open circuited. The currents in the lines are shown. The magnitude of $I_{b1}$ is______A.

• A. 5.77

Answer 1

The correct option is A 5.77
$I_{a1}=\frac{1}{3}[I_a+\lambda I_b+{\lambda }^2{I}_c]$

$I_{a1}=\frac{1}{3}[10+(10\angle 180\times 1\angle 120)+1\angle 240\times 0]$

$=\frac{1}{3}[10+10\angle 300]$

$I_{a1}=\frac{10\sqrt{3}}{3}\angle -30A$

$I_{b1}={\lambda }^2.I_{a1}$

( ${\lambda }^2=1\angle 240=1\angle -120$ )

$=5.77\angle -30\times 1\angle -120$

$I_{b1}=5.77\angle -150Amp$