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Three-Phase Systems in Power Applications - Engineering

Q1:

If in a Y-connected ac generator, each phase voltage has a magnitude of 90 VRMS, what is the magnitude of each line voltage?

A 0 V

B 90 V

C 156 V

D 180 V

ANS:C - 156 V

Vphase(max) = Vr.m.s/.707.

= 90/.707.

Vphase(max = 127.29 v.

Now in star connected networks.

V(line) = 1.732*V(phase).

= 1.732*127.29.

= 220 v.

I think it is the correct answer.