[dcb]

this of course assumes sine wave drive.

but the current through a leg is determined by the sine of its angle, i.e. leg 1 @ 90, leg 2 @ 210, leg 3 @ 330 would be 1, -.5, -.5 which as noted sums to zero. If you examine it at 90 electrical degrees then current in leg 1 should be the max current a leg will see.