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In a balanced 3-phase 4-wire system (star/Y), line-to-line voltage relates to phase voltage as:
AV_L = √3 V_ph (and lags by 30° w.r.t. corresponding V_ph)
BV_L = V_ph
CV_L = V_ph/√3
DV_L = 3 V_ph
Answer & Solution
Correct answer: A. V_L = √3 V_ph (and lags by 30° w.r.t. corresponding V_ph)
3-phase star: V_LL = √3 × V_ph. Currents: I_L = I_ph. India: V_LL = 415 V, V_ph = 240 V (3-phase 4-wire LT). In delta: V_LL = V_ph, but I_L = √3 × I_ph. Total power: √3 × V_LL × I_L × cos φ.
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