Question

Let Vab =300 V in a balanced Y-connected

 three-phase generator with a phase

 sequence acb, then Vbn is:

 Select one:

 a 173L-30° V

 b 173L-150° V

 c 173L+150° V

 d 173L-270° V

 e 173L +30° V

Answer 1

Look at the diagram:

The phase difference between Van and Vab is -30°. The phase difference between Van and Vbn is -120°. Thus, the phase shift between Vab and Vbn is -150°. The magnitude is

$$V_{bn}=\frac{V_{L}}{\sqrt3}=173\text{ V}.$$

The answer is

$$V_{bn}=173\angle-150°.$$