In a Delta (Δ) configuration, how are line current and phase current related, and how are line voltage and phase voltage related?

• A. Iline = √3 × Iphase; Vline = Vphase
• B. Iline = Iphase; Vline = √3 × Vphase
• C. Iline = 3 × Iphase; Vline = Vphase
• D. Iline = √3 × Iphase; Vline = √3 × Vphase

Answer: (A)

In a Delta configuration, each load element sits between two lines, so the voltage across each element is the line-to-line voltage. That makes the line voltage equal to the phase (branch) voltage. The line current, on the other hand, is the vector sum of the currents in the two branches connected to that line. For a balanced system, those branch currents are 120 degrees apart, and their phasor sum yields a line current whose magnitude is √3 times the branch (phase) current. So the line current is √3 times the phase current, while the line voltage equals the phase voltage.