From coil current to phase current in a delta system, how is the phase current obtained?

From coil current to phase current in a delta system, how is the phase current obtained?

• A. Multiply coil current by sqrt(3)
• B. Divide coil current by sqrt(3)
• C. Subtract coil current from line current
• D. Add coil current to line current

Answer: (B)

In a delta-connected system, the current through each winding (the phase current) is not the same as the current drawn from the supply lines (the coil/line current). The line current is the vector sum of two winding currents, which results in a magnitude relation: I_line = sqrt(3) × I_phase. So to obtain the phase current from the coil/line current, you divide by sqrt(3). Remember that the phase currents are 120 degrees apart, and the line currents are offset by 30 degrees relative to the phase currents in a balanced delta.

In a delta-connected system, the current through each winding (the phase current) is not the same as the current drawn from the supply lines (the coil/line current). The line current is the vector sum of two winding currents, which results in a magnitude relation: I_line = sqrt(3) × I_phase. So to obtain the phase current from the coil/line current, you divide by sqrt(3). Remember that the phase currents are 120 degrees apart, and the line currents are offset by 30 degrees relative to the phase currents in a balanced delta.