Question

Calculate the line voltage in star connection when phase voltage=45 V.

(a) 77.9 V

(b) 77.6 V

(c) 77.2 V

(d) 77.8 V

The question was asked by my school teacher while I was bunking the class.

This interesting question is from Induction Motors Speed Control in chapter Speed Control of Direct Current Motors & Induction Motors of Electric Drives

Answer 1

Right choice is (a) 77.9 V

For explanation: The line voltage in case of star connection is 1.73 times of phase voltage. It leads the phase voltage by an angle of 30°. VL-L=1.73×45=77.9 V.