Three 400 Ω resistors form a delta supplied by balanced 400 V RMS, 50 Hz, R-Y-B three-phase three-wire mains. Find line current in A, to one decimal place.
In a delta, each resistor sees the line voltage, so branch current is $I_{ph}=400/400=1$ A RMS. The line current is the phasor difference of two branch currents 120° apart, with magnitude $\sqrt3I_{ph}=1.732$ A. Rounded to one decimal place it is 1.7 A.
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