In a balanced wye-connected system, does line current equal phase current?

In a balanced wye-connected system, does line current equal phase current?

• A. Increases with each phase
• B. Doubles
• C. The line current varies with load
• D. Stays the same

Answer: (D)

In a balanced wye-connected system, each line carries the current of its own phase winding. Because the load is balanced, the three phase currents have equal magnitudes and are 120 degrees apart, and the neutral carries no current, but the current flowing in a line is simply the current through that phase. There’s no extra factor multiplying the current in the line, which is why the line current equals the phase current (in magnitude and angle). This is different from a delta connection, where the line current is related to the phase current by a factor of sqrt(3).

In a balanced wye-connected system, each line carries the current of its own phase winding. Because the load is balanced, the three phase currents have equal magnitudes and are 120 degrees apart, and the neutral carries no current, but the current flowing in a line is simply the current through that phase. There’s no extra factor multiplying the current in the line, which is why the line current equals the phase current (in magnitude and angle). This is different from a delta connection, where the line current is related to the phase current by a factor of sqrt(3).